Three-Arms PLA/PS Copolymer Based on 2,5-Dihydroxy-1,4-Benzoquinone

Three-Arms PLA/PS Copolymer Based on 2,5-Dihydroxy-1,4-Benzoquinone | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Three-Arms PLA/PS Copolymer Based on 2,5-Dihydroxy-1,4-Benzoquinone Dmitrii V Ludin, Ekaterina V Bobrina, Ivan D Grishin, Sergey D Zaitsev, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3821429/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 17 Jun, 2024 Read the published version in Journal of Polymer Research → Version 1 posted 5 You are reading this latest preprint version Abstract This study focuses on preparation of hybrid block copolymers of polylactide (PLA) and polystyrene (PS) involving 2,5-dihydroxy-1,4-benzoquinone (DHBQ) as a dual initiator. At the first stage in the presence of AcONa 2,5-dihydroxy-1,4-benzoquinone opened the lactide ring resulting in the carboxylic end-group that further provides for the PLA chain growth. The polymerization proceeds at a moderate rate to high conversion degrees to form the polymers with well-defined molecular weight (MW) characteristics. The presence of an internal DHBQ fragment in the polymer was proven by IR, UV-VIS, NMR and MALDI-TOF techniques. Obtained polymer can be considered as macroquinone (MQ). The styrene polymerization initiated by MQ/Bu 3 B proceeds at a moderate rate leading to the formation of hybrid three-radial PLA/PS copolymer. During the copolymer formation linear increase of M n with conversion as well as polydispersity decrease were observed. As evidenced by relatively low content of polystyrene in the copolymer (8.1 wt. %), the process has a good selectivity. The introduction of styrene units into the copolymer allows a 4-fold increase the E modulus in comparison with the homo-PLA. p-quinone polylactide polystyrene copolymers tributylborane Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction In the late 1950s trialkylboranes were used for the first time to initiate radical polymerization [ 1 , 2 ]. To date organoboranes are widely applied for the preparation of various polymeric materials. A well-known autooxidation of triethylborane causes an appearance of a number of radicals that easily initiate the polymerization of different vinylic monomers. T.C. Chung et al demonstrated that the polymerization of MMA proceed in a controlled manner due to the reversible inhibition by boroxyl radicals (Scheme 1 ) [ 3 ]. However, due to a complicated polymerization mechanism the preparation of (co)polymers with well-defined MW characteristics in these processes is still challenging [ 3 – 6 ]. On the other hand, organoborane/air oxygen systems have been extensively used to prepare various copolymers including those containing natural polymers [ 7 – 12 ]. Recently A.J.D. Magenau et al proposed adhesives based on tributylborane 3-methoxypropylamine complex [ 13 ]. An alkylborane initiated RAFT-polymerization (AI-RAFT) method was developed independently in the groups of X. Pan [ 14 – 17 ] and A.J.D. Magenau [ 18 – 20 ] during last years. The AI-RAFT polymerization mechanism is shown in Scheme 2 . The polymerization is initiated by various C- and O-centered radicals that formed during oxidation of trialkylborane by air oxygen. In contrast to classic RAFT polymerization, the AI-RAFT reveals (i) a high rate at room temperature; (ii) O 2 tolerance; (iii) low-to-moderate polydispersity. Using AI-RAFT approach the thiol-ene and thiol-yne networks can be obtained [ 21 , 22 ]. Further, photo-initiated RAFT polymerization with 1,3-diaminopropane-triethylborane/diphenyl iodonium salt system has been developed [ 23 ]. It proceeds at ambient conditions at a high rate and affords polymers featuring a narrow MW distribution. Using well-defined polymers containing functional end-groups the facile and efficient techniques for preparing block copolymers by chain extension and Suffix click post reaction were developed. Alkylcateholboranes were synthesized and investigated as the RAFT polymerization initiators [ 24 ]. The obtained polymers reveal ultrahigh MWs ( M n ~ 10 6 ) and good polydispersities. In addition to the boron-based RAFT agents, p -quinones are also used in a reversible deactivation radical polymerization [ 25 – 27 ]. In contrast to organoborane/air oxygen systems, p -quinones lack uncontrolled autoxidation. It has a positive impact on the MW characteristics of the resulting polymers. Trialkylborane/ p -quinone systems are used in the synthesis of hybrid copolymers with various natural substrates [ 28 – 30 ] and polylactide [ 31 ]. In addition to radical polymerization trialkylboranes are actively used in ring-opening polymerization. In 2016 the possibility of obtaining alternating copolymers of epoxides and carbon dioxide under the action of triethylborane together with ammonium and phosphonium bases was demonstrated for the first time [ 32 ]. Later on, DBU and TBD were also used [ 33 ]. A wide range of (co)polymers involving epoxides, anhydrides, lactones and isocyanates have been prepared with such catalytic systems [ 34 – 40 ]. Current advances in ring-opening copolymerization area, involving triethylborane and various bases, are summarized in a recent review [ 41 ]. In the most recent studies, chiral diboranes have been proposed to synthesize isotactic polymers from racemic monomers [ 42 , 43 ]. Hybrid block copolymers of vinyl monomers with epoxides, anhydrides, and lactide were obtained by simultaneous self-switchable copolymerization in the presence of triethylborane, organic bases and RAFT-agent [ 44 , 45 ]. In these syntheses, the RAFT-agent acted as the ring-opening polymerization initiator and the mediator of radical polymerization (Scheme 3 ). The resulting products revealed low polydispersity and a high degree of conversion of monomers. RDRP methods are widely used to obtain grafted and block copolymers of polylactide and vinyl polymers [ 46 ]. These works have particular value because they offer methods for obtaining copolymers from monomers that polymerize by essentially different mechanisms. Considering the possibility of controlling physical and mechanical properties by introducing a synthetic polymer block, this research area has not only fundamental importance, but also a pronounced practical significance. Despite the steady development of alkylborane chemistry in the field of ring-opening polymerization and reversible-deactivation radical polymerization, just a few works are devoted to preparation of hybrid polyester/poly(vinyl monomer) copolymers. Therefore we initiated a study aimed on the obtaining block copolymers of polylactide (PLA) and polystyrene (PS) involving tributylborane (TBB) and 2,5-dihydroxy-1,4-benzoquinone (DHBQ). In the present work we propose the synthetic approach to radial PLA/PS copolymer. Results and discussion Our approach to PS/PLA copolymers consists of two key processes. The first one involves the lactide ring-opening polymerization initiated by DHBQ. It is worth noting that without additives the lactide and DHBQ do not react. As an activator for this couple we have chosen sodium acetate because activation of alcohols towards cyclic monomers (e.g. lactide) using group 1 metal carboxylates has been recently demonstrated by T. Saito et al [47-51]. It was found that increasing the alkali metal radius contributes to increasing the polymerization rate. However, the heavy group 1 metal salts, e.g. of potassium or cesium derivatives are more hygroscopic in comparison with analogous derivatives of lithium and sodium. The presence of water in the activator causes the formation of by-products and deviation of M n as well as of conversion degree from the theoretical values. Therefore, we have taken commercially available sodium acetate (Aldrich) and removed the water traces from the sample prior to use. The sequence of reactions that lead to the PS/PLA copolymers is shown in Scheme 4 and Scheme 5 (for experimental details see Supporting Information). As it was established by T. Saito the lactide polymerization in the presence of AcONa and ROH is initiated by RO – species [51]. Similarly, sodium acetate can activate DHBQ to generate di- O -nucleophile that is able to open the lactide ring (Scheme 4). Repeated activation of carboxylic end-groups by AcONa must provide for the polymeric chain propagation and result in the macromolecule that contains a central quinone fragment (macroquinone, MQ). Similar to low molecular weight p -quinones, MQ must possess inhibitory properties in radical polymerization. In the presence of trialkylboranes, the p -quinones will lose their inhibitory properties, becoming a controlled radical polymerization agents. It is known, that the styrene polymerization is inhibited by p -quinone via carbonyl group [52]. The interaction between the macroradical and MQ will result in the formation of phenoxyl radicals, which further engage in the S H 2-substitution reaction at the boron atom. The reactions proceed at a very high rate ( k ~ 10 6 -10 8 L∙mol –1 ∙s –1 ) [53]. The resulting macromolecules with an aryloxyborane terminal group are capable of reversible homolytic dissociation, reinitiating the polymerization process (Scheme 5) [25]. In the case of low molecular weight p -quinones (2,3-dimethyl-1,4-benzoquinone, menadione, 1,4-naphthoquinone, and duroquinone), the dissociation of such macromolecules is described by equation: Thus, introduction of PLA chains in DHBQ may allow the preparation of hybrid copolymers. In the first step, the lactide polymerization in the presence of AcONa and DHBQ was studied. At a component ratio [LA]/[AcONa]/[DHBQ] = 100/1/1 at 110 °C, polymerization is completed in about 40 hours (Fig. 1a). Increasing the temperature to 120 °C promotes a regular increase in the polymerization rate. The linear dependence ln([M] 0 /[M]) vs conversion indicates the constant number of reaction centers in the polymerization process (Fig. 1b). This fact indicates the first order of the chain growth reaction in terms of monomer concentration. Also, this fact is the sign of controlled polymerization. The polymers’ molecular weight increases uniformly with increasing conversion (Fig. 1c). The polymers obtained at 110 °C are characterized by the coincidence of M n values with those calculated theoretically by equation: where [LA] 0 is initial lactide concentration, [DHBQ] 0 is initial DHBQ concentration, M (LA) is molar weight of LA (144 g ∙ mol –1 ) and M (DHBQ) is molar weight of DHBQ (140 g ∙ mol –1 ). Only at deep conversions (above 80 %), a positive deviation from the theoretical data is observed. Increasing the temperature leads to a pronounced deviation of M n from the linear dependence already at moderate conversions (Fig. 1c). Similar deviations appear on the M w / M n vs conversion curve. In general, the synthesized PLA polydispersity remains relatively low ( M w / M n = 1.13-1.23). Increasing the polymerization temperature leads to broadening of the molecular weight distribution. GPC traces shift uniformly to the region of higher molecular weights with increasing conversion (Fig. 1d). Nevertheless, at deep conversions, a shoulder peak is registered on the GPC-curves. Its presence is related with the trans-esterification process. As the polymerization temperature increases up to 120 °C the bimodality of the molecular weight distribution curve becomes more evident (Fig. 1S). Increasing the concentration of AcONa in the initial feed promotes an increase in the polymerization rate and a decrease in the molecular weight limit achieved (Table 1). The MW dispersion remains low-to-moderate ( M w / M n = 1.13-1.27) irrespective of the component ratio. Table 1. ROP of LA in the presence of AcONa and DHBQ at 110 °C. [LA]/[AcONa]/[DHBQ] Time, h Conversion, % a M n, theo · 10 –3 b M n, GPC · 10 –3 c M w / M n c 50/1/1 27 89.9 6.61 6.52 1.27 100/1/1 27 86.1 12.5 13.6 1.21 200/1/1 27 75.0 21.7 19.9 1.18 300/1/1 48 60.6 26.3 23.9 1.17 400/1/1 72 45.2 26.1 24.0 1.13 500/1/1 72 39.3 28.4 26.1 1.15 a Determined by 1 H NMR; b Calculated according to eq. (2); c Determined by GPC in THF. Examination of polymer end groups by MALDI-TOF confirmed the supposed ring-opening polymerization mechanism. According to MALDI-TOF data, all macromolecules have a DHBQ unit (Fig. 2), i.e. they can be attributed to MQ. Since the mobility of hydrogen atoms at OH-groups in DHBQ is relatively high, we believe that both functional groups are involved in the polymerization almost simultaneously. In the area of high molecular masses the MALDI-TOF spectrum shows some peaks corresponding to esterification products (they are highlighted in red rectangle). The analysis of PLA obtained at 120 °C showed that the intensity of the peaks corresponding to trans-esterification products is significantly higher (Fig. 2S). This is in good agreement with the data obtained by the GPC method. Thus, with increasing polymerization temperature, the trans-esterification process becomes more visible that affects negatively the polymers’ polydispersity. To prove the presence of DHBQ unit in macromolecules the 1 H NMR, IR and UV-VIS spectroscopy studies were carried out. According to FT-IR data, the polymer has two types of carbonyl groups whose stretching vibrations are located at 1760 and 1659 cm –1 . They belong to the monomer and DHBQ linkages, respectively (Fig. 3a). Due to a yellow coloring of MQ, the UV-VIS spectroscopy can be successfully applied for analysis. Absorption band of MQ (315 nm) is shifted to the short-wave region relative to the initial DHBQ (390 nm, Fig. 3b). With increasing of the length of polymeric chains in MQ the coloration becomes less intense. The appearance of the hypsochromic shift indicates a changing the nature of the substituents in the DHBQ molecule. Similar changes were observed earlier, while studying the inhibited polymerization of methyl methacrylate [54]. The 1 H NMR spectrum of PLA contains peaks that correspond to the end alcohol groups of macromolecules (Fig. 3c). The signals related to the protons of the quinone ring are registered at 6.08 ppm. The analysis of the signal of the PLA methine group indicates the epimerization in the polymerization process. The process temperature variation has little effect on the polymer’s tacticity. In view of the overlapping peaks corresponding to different triads, it is impossible to calculate the probabilities of P m and P r . In general, the resulting MQ can be classified as a heterotactic polymer. Thus, under the action of AcONa/DHBQ system PLA with well-defined molecular weight characteristics containing a p -quinone fragment in the polymer chain was obtained. The presence of the internal quinone unit opens the possibility for further PLA modification by block copolymerization with vinyl monomers. It is known that the radical styrene polymerization in the presence of the TBB/ p -quinone system proceeds by the reversible inhibition mechanism [25]. Macromolecules with terminal aryloxyborane groups are responsible for the dissociation-recombination process. Formation of such terminal groups is the result of a sequence of inhibition and subsequent S H 2-substitution reactions (Scheme 5). Re-initiation of radical polymerization is characterized by the activation energy E a = 113.3 kJ ∙ mol –1 [25]. The TBB/p-quinone system is similar to the widely used alkylborane/air oxygen system. But due to the absence of uncontrolled borane autoxidation, a higher degree of radical polymerization control is achieved. A wide range of (co)polymers, including hybrid polymers, were obtained using the TBB/ p -quinone system. To obtain PS/PLA copolymers in the presence of TBB, MQ was used as an inhibitor of styrene polymerization. AIBN-initiated polymerization of styrene at 80 °C in THF in the presence of MQ and TBB proceeds at a moderate rate (Fig. 4a). During the process the MQ loses its coloring due to the conversion of its quinoid structure to an aromatic one. This process is manifested by the disappearance of the absorption band at 315 nm. The linear dependence of ln([M] 0 /[M]) vs time indicates the controlled radical polymerization (Fig. 4a). The block copolymers are characterized by linear growth of M n with conversion as well as moderate polydispersity values (Fig. 4b). With increasing conversion depth the molecular weight distribution curves are shifted to the area of higher molecular weights (Fig. 4c). On the GPC curve corresponding to the initial conversion copolymer there is a "shoulder" coinciding with the MQ curve. This fact indicates the slow consumption of MQ in the polymerization process. With increasing conversion the shoulder height is decreasing and after reaching the conversion of 17.6 % this peak disappears completely. Based on GPC data the MQ can be described as a weak inhibitor of radical polymerization. With decreasing MQ concentration in the reaction feed a regular increase of polymerization rate, of copolymer molecular weight as well as of polydispersity were observed (Fig. 4d). Increasing the concentration of TBB in the initial feed does not affect the polymerization kinetics and molecular weight characteristics. This fact corresponds to the polymerization scheme, according to which the limiting stage is inhibition. In addition, the presence of air oxygen traces cannot contribute to the polymerization start, since styrene is not sensitive to the alkylborane/air oxygen system [1]. The copolymers’ composition was analyzed by 1 H nuclear magnetic resonance spectroscopy. The NMR spectrum clearly shows the signals corresponding to LA and styrene units (Fig. 5a). As the degree of conversion increases, enrichment of the copolymer with styrene fragments is observed (Fig. 4b). The formation of equimolar composition copolymers is observed when the conversion rate reaches 15 %. In addition to the reactions presented in Scheme 5, recombination of macroradicals leading to the homopolymer formation cannot be excluded. To separate the hybrid copolymer from the homopolymer an extraction in a Soxhlet apparatus was carried out. After 40 h, 8.10 wt. % of polystyrene was isolated from the extractant solution, which was identified by IR spectroscopy (Fig. 4S). The grafting degree of 91.9 % was calculated according to equation (3). DSC study of the hybrid copolymers showed the presence of two glass transition temperatures ( T g ) corresponding to PLA and PS blocks (Fig. 5b). The glass transition of PLA synthesized in the presence of AcONa and DHBQ is observed at 55.6 °C. In the hybrid copolymer the T g value of the PLA block is increased in 7.7 °C. In contrast, the T g of the PS block decreases by 7.5 °C relative to the homopolystyrene, which is characterized by T g = 100.1 °C. These deviations can additionally confirm the fact of copolymer formation. The different nature of the hybrid copolymer blocks is reflected in the physical and mechanical properties. , In contrast to PS synthesized by conventional radical polymerization the MQ synthesized in this work exhibits pronounced elastic properties (Table 3). The hybrid copolymer is also characterized by small E modulus and large strains (up to 387 %). However, the introduction of 38 % PS allows increasing the E modulus by 4 times and reducing the strain value by 149 %. Table 3. Mechanical properties of (co)polymers Polymer Tensile strength, MPa Deformation, % E modulus, MPa PS 1 17.6±2.94 7.41±0.57 2.37 ∙ 10 3 MQ 2 0.87±0.16 536±44.0 1.62 PS/PLA 3 2.60±0.12 387±65.4 6.73 1 PS prepared by conventional radical polymerization, M n = 50,000; 2 Prepared using AcONa and DHBQ: [LA]/[AcONa]/[DHBQ] = 100/1/1, M n = 15,800 kDa; 3 PLA mole fraction is 62 mol %, M n = 25,800. Conclusion Thus, an original method of styrene and PLA copolymerization using TBB and DHBQ leading to the hybrid copolymer formation has been proposed. The AcONa/DHBQ system is demonstrated to promote the controlled PLA synthesis, which is confirmed by the analysis of polymerization kinetics, linear dependence of M n with conversion and low polydispersity values. MALDI TOF, FT-IR, UV-VIS and 1 H NMR data clearly indicate the presence of DHBQ fragment in the polymer chain. The synthesized PLA can be described as macroquinone capable of mediating radical styrene polymerization in the presence of TBB. Styrene polymerization in the presence of TBB/MQ leads to the formation of a hybrid copolymer with distinct molecular weight characteristics. The small homopolymer content in the copolymerization product positively characterizes this process from the point of selectivity. The introduction of styrene to the copolymer allows increasing the E modulus and reducing the strain value. 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Macromolecules 54:9474–9481. https://doi.org/10.1021/acs.macromol.1c01460 Varghese JK, Hadjichristidis N, Gnanou Y, Feng X (2019) Degradable poly(ethylene oxide) through metal-free copolymerization of ethylene oxide with L -lactide. Polym Chem 10:3764–3771. https://doi.org/10.1039/C9PY00605B Zhu S, Wang Y, Ding W, Zhou X, Liao Y, Xie X (2020) Lewis pair catalyzed highly selective polymerization for the one-step synthesis of A z C y (AB) x C y A z pentablock terpolymers. Polym Chem 11:1691–1695. https://doi.org/10.1039/C9PY01508F Jia M, Hadjichristidis N, Gnanou Y, Feng X (2021) Polyurethanes from direct organocatalytic copolymerization of p -tosyl isocyanate with epoxides. Angew Chem Int Ed 60:1593–1598. DOI: https://doi.org/10.1002/anie.202011902 Liu J, Gnanou Y, Feng X (2021) Expanding the scope of boron-based ate complexes by manipulating their reactivity: the case of cyclic esters and their (co)polymers. Macromolecules 55:1800–1810. https://doi.org/10.1021/acs.macromol.1c02195 Zhang C, Geng X, Zhang X, Gnanou Y, Feng X (2023) Alkyl borane-mediated metal-free ring-opening (co)polymerizations of oxygenated monomers. Prog Polym Sci 136:101644. https://doi.org/10.1016/j.progpolymsci.2022.101644 Du P, Li Y, Lu X-B (2023) Chiral organoboron-mediated alternating copolymerization of meso-epoxides with CO 2 . Macromolecules 56:6783–6789. https://doi.org/10.1021/acs.macromol.3c01264 Sirin-Sariaslan A, Naumann S (2023) Sterically demanding binaphthol-based chiral diboranes for metal-free and isotactic poly(propylene oxide). Chem Commun 59:11069–11072. https://doi.org/10.1039/D3CC02889E Xia Y, Scheutz GM, Easterling CP, Zhao J, Sumerlin BS (2021) Hybrid block copolymer synthesis by merging photoiniferter and organocatalytic ring-opening polymerizations. Angew Chem Int Ed 60:18537–18541. https://doi.org/10.1002/anie.202106418 Zhu S, Zhao Y, Ni M, Xu J, Zhou X, Liao Y et al (2020) One-step and metal-free synthesis of triblock quaterpolymers by concurrent and switchable polymerization. ACS Macro Lett 9:204–209. https://doi.org/10.1021/acsmacrolett.9b00895 Yildirim I, Weber C, Schubert US (2018) Old meets new: combination of PLA and RDRP to obtain sophisticated macromolecular architectures. Prog Polym Sci 76:111–150. https://doi.org/10.1016/j.progpolymsci.2017.07.010 Saito T, Aizawa Y, Yamamoto T, Tajima K, Isono T, Satoh T (2018) Alkali metal carboxylate as an efficient and simple catalyst for ring-opening polymerization of cyclic esters. Macromolecules 51:689–696. https://doi.org/10.1021/acs.macromol.7b02566 Xia X, Suzuki R, Takojima K, Jiang D-H, Isono T, Satoh T (2021) Smart access to sequentially and architecturally controlled block polymers via a simple catalytic polymerization system. ACS Catal 11:5999–6009. https://doi.org/10.1021/acscatal.1c00382 Takojima K, Saito T, Vevert C, Ladelta V, Bilalis P, Watanabe J et al (2020) Facile synthesis of poly(trimethylene carbonate) by alkali metal carboxylate-catalyzed ring-opening polymerization. Polym J 52:103–110. https://doi.org/10.1038/s41428-019-0264-6 Xia X, Suzuki R, Gao T, Isono T, Satoh T (2022) One-step synthesis of sequence-controlled multiblock polymers with up to 11 segments from monomer mixture. Nat Commun 13:163. https://doi.org/10.1038/s41467-021-27830-3 Ozen C, Satoh T, Maeda S (2020) A theoretical study on the alkali metal carboxylate-promoted L -lactide polymerization. J Comput Chem 41:2197–2202. https://doi.org/10.1002/jcc.26386 Tüdős F, Földes-Berezsnich T (1989) Free radical polymerization: inhibition and retardation. Prog Polym Sci 14:717–761. https://doi.org/10.1016/0079-6700(89)90008-7 Griller D, Ingold KU, Patterson LK, Scaiano JC, Small RD (1979) A study of transient phenomena in the reactions of alkoxy radicals with triphenylphosphine and triphenylborane. J Am Chem Soc 101:3780–3785. https://doi.org/10.1021/ja00508a014 Dodonov VA, Kuznetsova YL, Lopatin MA, Skatova AA (2004) Reactions of poly(methyl methacrylate) radicals with some p -quinines in the presence of tri- n -butylboron in methyl methacrylate polymerization. Russ Chem Bull 53:2209–2214. https://doi.org/10.1007/s11172-005-0101-2 Schemes Schemes 1-5 are available in the Supplementary Files section. Supplementary Files Graphicalabstract.doc SUPPORTINGINFORMATION.doc Schemes.docx Cite Share Download PDF Status: Published Journal Publication published 17 Jun, 2024 Read the published version in Journal of Polymer Research → Version 1 posted Reviewers agreed at journal 05 Feb, 2024 Reviewers invited by journal 18 Jan, 2024 Editor invited by journal 07 Jan, 2024 Editor assigned by journal 02 Jan, 2024 First submitted to journal 01 Jan, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3821429","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":268167438,"identity":"a916c72d-ac3e-48fe-b605-1e7b39f223eb","order_by":0,"name":"Dmitrii V Ludin","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAwklEQVRIiWNgGAWjYDCCA2DSBoh5GA+QoiUNpIWBJC2HSdDCdyM78eOPP+fz+aedPXDg4x6GfANCGiVv5G6W5m27bTnjdl7CwRnPGCw3ENJicCN3gzRjw20Dhts5Bod5DjAYELQFqGXzzx9/zhnIg7T8IVLLNgketgMGBiAtDMRokTzzdps1b1uygSHILz0HJAwkCWnhO567+eaPP3YGcrdzDz74ccDGgI+QFgaBBBSuBCH1QMBP0NBRMApGwSgY8QAARmNMFIG2rK4AAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0001-5401-588X","institution":"Lobachevsky State University of Nizhny Novgorod","correspondingAuthor":true,"prefix":"","firstName":"Dmitrii","middleName":"V","lastName":"Ludin","suffix":""},{"id":268167439,"identity":"5a5eed46-34f5-442f-992e-589a7d0bb0dc","order_by":1,"name":"Ekaterina V Bobrina","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Ekaterina","middleName":"V","lastName":"Bobrina","suffix":""},{"id":268167440,"identity":"1a9aaf81-465e-4b56-989f-c480998a6c84","order_by":2,"name":"Ivan D Grishin","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Ivan","middleName":"D","lastName":"Grishin","suffix":""},{"id":268167441,"identity":"86feaeb0-23ee-4ac7-a048-807bd67ccef6","order_by":3,"name":"Sergey D Zaitsev","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Sergey","middleName":"D","lastName":"Zaitsev","suffix":""},{"id":268167442,"identity":"d6872cc3-f7cd-4847-b2a1-2b1da112f042","order_by":4,"name":"Igor L Fedushkin","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Igor","middleName":"L","lastName":"Fedushkin","suffix":""}],"badges":[],"createdAt":"2023-12-29 13:32:45","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3821429/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3821429/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10965-024-04040-1","type":"published","date":"2024-06-18T00:35:24+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":50116122,"identity":"c56d494e-7ad6-4001-8629-0d5ebb541e29","added_by":"auto","created_at":"2024-01-24 18:48:13","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":43636,"visible":true,"origin":"","legend":"\u003cp\u003e(\u003cem\u003ea\u003c/em\u003e) Kinetic curves of LA polymerization at 110 and 120 °C; (\u003cem\u003eb\u003c/em\u003e) first-order kinetic plot for the ROP of LA at 110 and 120 °C; (\u003cem\u003ec\u003c/em\u003e) dependence of \u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e, \u003cem\u003eM\u003c/em\u003e\u003csub\u003ew\u003c/sub\u003e/\u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e and \u003cem\u003eM\u003c/em\u003e\u003csub\u003en,theo\u003c/sub\u003e (dotted line) on the monomer conversion; (\u003cem\u003ed\u003c/em\u003e) GPC-traces of PLA obtained at 110 °C. [LA]/[AcONa]/[DHBQ] = 100/1/1.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-3821429/v1/deefe6017a310e9d7db9e16c.png"},{"id":50117332,"identity":"fed13cfd-dd20-4cde-b925-ed04ac435b54","added_by":"auto","created_at":"2024-01-24 18:56:13","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":24623,"visible":true,"origin":"","legend":"\u003cp\u003eMALDI-TOF MS spectrum of PLA obtained from [LA]/[AcONa]/[DHBQ] = 100/1/1 (conv. 35 % \u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e = 5362, \u003cem\u003eM\u003c/em\u003e\u003csub\u003ew\u003c/sub\u003e/\u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e = 1.10), expected structures and theoretical molecular weights of the PLA possessing a DHBQ unit and a OH-group at the ω-chain end.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-3821429/v1/4190c89d79676eeba3d65cae.png"},{"id":50116125,"identity":"648ce8f8-a556-4700-9fa9-e26232c59374","added_by":"auto","created_at":"2024-01-24 18:48:13","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":35697,"visible":true,"origin":"","legend":"\u003cp\u003e(\u003cem\u003ea\u003c/em\u003e) The FT-IR spectrum of PLA, obtained from [LA]/[AcONa]/[DHBQ] = 50/1/2; (\u003cem\u003eb\u003c/em\u003e) the UV-VIS spectra of PLA isolated at different conversions, [LA]/[AcONa]/[DHBQ] = 100/1/1; (\u003cem\u003ec\u003c/em\u003e) the \u003csup\u003e1\u003c/sup\u003eH NMR spectrum of MQ obtained from [LA]/[AcONa]/[DHBQ] = 50/1/2.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-3821429/v1/917aa010b879e67d93cac35c.png"},{"id":50116124,"identity":"bbe07f55-215b-43d1-8971-359a0708bb1d","added_by":"auto","created_at":"2024-01-24 18:48:13","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":45693,"visible":true,"origin":"","legend":"\u003cp\u003e(\u003cem\u003ea\u003c/em\u003e) Plots of styrene conversion \u003cem\u003evs\u003c/em\u003e time and first-order kinetic plot for the copolymerization at 80°C; (\u003cem\u003eb\u003c/em\u003e) Dependence of \u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e and \u003cem\u003eM\u003c/em\u003e\u003csub\u003ew\u003c/sub\u003e/\u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e with conversion and mole fraction of PLA with \u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e; (\u003cem\u003ec\u003c/em\u003e) Evolution of GPC traces; (\u003cem\u003ed\u003c/em\u003e) GPC curves of initial MQ and block copolymer, synthesized at 80°C for 3 hours.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-3821429/v1/efa0df5e0978d6817227465d.png"},{"id":50117333,"identity":"b4e23f46-821a-4907-a607-1861e3bc0a97","added_by":"auto","created_at":"2024-01-24 18:56:13","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":15691,"visible":true,"origin":"","legend":"\u003cp\u003e(\u003cem\u003ea\u003c/em\u003e) \u003csup\u003e1\u003c/sup\u003eH NMR spectrum of PS/PLA copolymer isolated at 25.5% conversion; (\u003cem\u003eb\u003c/em\u003e) DSC curves of hybrid copolymer, MQ and PS, synthesized by conventional radical polymerization.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-3821429/v1/3babfd0c1d79fb691e497d1c.png"},{"id":58613932,"identity":"01974aa4-cf0a-494d-a871-71ddd9356100","added_by":"auto","created_at":"2024-06-19 00:35:33","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":537279,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3821429/v1/83dc58b5-4f89-4df6-9ad4-221364910a9c.pdf"},{"id":50116127,"identity":"80b95323-0b03-4179-9313-d4fc7f78407c","added_by":"auto","created_at":"2024-01-24 18:48:13","extension":"doc","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":91136,"visible":true,"origin":"","legend":"","description":"","filename":"Graphicalabstract.doc","url":"https://assets-eu.researchsquare.com/files/rs-3821429/v1/7a743ec3570d746ed7e9cb72.doc"},{"id":50116129,"identity":"e3d4735b-ccf1-4591-8000-7b6134f54f85","added_by":"auto","created_at":"2024-01-24 18:48:13","extension":"doc","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":266240,"visible":true,"origin":"","legend":"","description":"","filename":"SUPPORTINGINFORMATION.doc","url":"https://assets-eu.researchsquare.com/files/rs-3821429/v1/c2dec8027a97ce46ff2dbe6e.doc"},{"id":50117334,"identity":"7a3359ce-0437-4757-88c7-ef3d4674d094","added_by":"auto","created_at":"2024-01-24 18:56:13","extension":"docx","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":185710,"visible":true,"origin":"","legend":"","description":"","filename":"Schemes.docx","url":"https://assets-eu.researchsquare.com/files/rs-3821429/v1/6bbdf48a9975b9010b49d25c.docx"}],"financialInterests":"","formattedTitle":"Three-Arms PLA/PS Copolymer Based on 2,5-Dihydroxy-1,4-Benzoquinone","fulltext":[{"header":"Introduction","content":"\u003cp\u003eIn the late 1950s trialkylboranes were used for the first time to initiate radical polymerization [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. To date organoboranes are widely applied for the preparation of various polymeric materials. A well-known autooxidation of triethylborane causes an appearance of a number of radicals that easily initiate the polymerization of different vinylic monomers. T.C. Chung et al demonstrated that the polymerization of MMA proceed in a controlled manner due to the reversible inhibition by boroxyl radicals (Scheme \u003cspan refid=\"Sch1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eHowever, due to a complicated polymerization mechanism the preparation of (co)polymers with well-defined MW characteristics in these processes is still challenging [\u003cspan additionalcitationids=\"CR4 CR5\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. On the other hand, organoborane/air oxygen systems have been extensively used to prepare various copolymers including those containing natural polymers [\u003cspan additionalcitationids=\"CR8 CR9 CR10 CR11\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Recently A.J.D. Magenau et al proposed adhesives based on tributylborane 3-methoxypropylamine complex [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. An alkylborane initiated RAFT-polymerization (AI-RAFT) method was developed independently in the groups of X. Pan [\u003cspan additionalcitationids=\"CR15 CR16\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] and A.J.D. Magenau [\u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] during last years. The AI-RAFT polymerization mechanism is shown in Scheme \u003cspan refid=\"Sch2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe polymerization is initiated by various C- and O-centered radicals that formed during oxidation of trialkylborane by air oxygen. In contrast to classic RAFT polymerization, the AI-RAFT reveals (i) a high rate at room temperature; (ii) O\u003csub\u003e2\u003c/sub\u003e tolerance; (iii) low-to-moderate polydispersity. Using AI-RAFT approach the thiol-ene and thiol-yne networks can be obtained [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Further, photo-initiated RAFT polymerization with 1,3-diaminopropane-triethylborane/diphenyl iodonium salt system has been developed [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. It proceeds at ambient conditions at a high rate and affords polymers featuring a narrow MW distribution. Using well-defined polymers containing functional end-groups the facile and efficient techniques for preparing block copolymers by chain extension and Suffix click post reaction were developed. Alkylcateholboranes were synthesized and investigated as the RAFT polymerization initiators [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The obtained polymers reveal ultrahigh MWs (\u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e ~ 10\u003csup\u003e6\u003c/sup\u003e) and good polydispersities. In addition to the boron-based RAFT agents, \u003cem\u003ep\u003c/em\u003e-quinones are also used in a reversible deactivation radical polymerization [\u003cspan additionalcitationids=\"CR26\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. In contrast to organoborane/air oxygen systems, \u003cem\u003ep\u003c/em\u003e-quinones lack uncontrolled autoxidation. It has a positive impact on the MW characteristics of the resulting polymers. Trialkylborane/\u003cem\u003ep\u003c/em\u003e-quinone systems are used in the synthesis of hybrid copolymers with various natural substrates [\u003cspan additionalcitationids=\"CR29\" citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] and polylactide [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn addition to radical polymerization trialkylboranes are actively used in ring-opening polymerization. In 2016 the possibility of obtaining alternating copolymers of epoxides and carbon dioxide under the action of triethylborane together with ammonium and phosphonium bases was demonstrated for the first time [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Later on, DBU and TBD were also used [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. A wide range of (co)polymers involving epoxides, anhydrides, lactones and isocyanates have been prepared with such catalytic systems [\u003cspan additionalcitationids=\"CR35 CR36 CR37 CR38 CR39\" citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. Current advances in ring-opening copolymerization area, involving triethylborane and various bases, are summarized in a recent review [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. In the most recent studies, chiral diboranes have been proposed to synthesize isotactic polymers from racemic monomers [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e, \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]. Hybrid block copolymers of vinyl monomers with epoxides, anhydrides, and lactide were obtained by simultaneous self-switchable copolymerization in the presence of triethylborane, organic bases and RAFT-agent [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]. In these syntheses, the RAFT-agent acted as the ring-opening polymerization initiator and the mediator of radical polymerization (Scheme \u003cspan refid=\"Sch3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The resulting products revealed low polydispersity and a high degree of conversion of monomers.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eRDRP methods are widely used to obtain grafted and block copolymers of polylactide and vinyl polymers [\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e]. These works have particular value because they offer methods for obtaining copolymers from monomers that polymerize by essentially different mechanisms. Considering the possibility of controlling physical and mechanical properties by introducing a synthetic polymer block, this research area has not only fundamental importance, but also a pronounced practical significance.\u003c/p\u003e \u003cp\u003eDespite the steady development of alkylborane chemistry in the field of ring-opening polymerization and reversible-deactivation radical polymerization, just a few works are devoted to preparation of hybrid polyester/poly(vinyl monomer) copolymers. Therefore we initiated a study aimed on the obtaining block copolymers of polylactide (PLA) and polystyrene (PS) involving tributylborane (TBB) and 2,5-dihydroxy-1,4-benzoquinone (DHBQ). In the present work we propose the synthetic approach to radial PLA/PS copolymer.\u003c/p\u003e"},{"header":"Results and discussion","content":"\u003cp\u003eOur approach to PS/PLA copolymers consists of two key processes. The first one involves the lactide ring-opening polymerization initiated by DHBQ. It is worth noting that without additives the lactide and DHBQ do not react. As an activator for this couple we have chosen sodium acetate because activation of alcohols towards cyclic monomers (e.g. lactide) using group 1 metal carboxylates has been recently demonstrated by T. Saito et al [47-51]. It was found that increasing the alkali metal radius contributes to increasing the polymerization rate. However, the heavy group 1 metal salts, e.g. of potassium or cesium derivatives are more hygroscopic in comparison with analogous derivatives of lithium and sodium. The presence of water in the activator causes the formation of by-products and deviation of \u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e as well as of conversion degree from the theoretical values. Therefore, we have taken commercially available sodium acetate (Aldrich) and removed the water traces from the sample prior to use. The sequence of reactions that lead to the PS/PLA copolymers is shown in Scheme 4 and Scheme 5 (for experimental details see Supporting Information).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAs it was established by T. Saito the lactide polymerization in the presence of AcONa and ROH is initiated by RO\u003csup\u003e\u0026ndash;\u003c/sup\u003e species [51]. Similarly, sodium acetate can activate DHBQ to generate di-\u003cem\u003eO\u003c/em\u003e-nucleophile that is able to open the lactide ring (Scheme 4). Repeated activation of carboxylic end-groups by AcONa must provide for the polymeric chain propagation and result in the macromolecule that contains a central quinone fragment (macroquinone, MQ). Similar to low molecular weight \u003cem\u003ep\u003c/em\u003e-quinones, MQ must possess inhibitory properties in radical polymerization. In the presence of trialkylboranes, the \u003cem\u003ep\u003c/em\u003e-quinones will lose their inhibitory properties, becoming a controlled radical polymerization agents. It is known, that the styrene polymerization is inhibited by \u003cem\u003ep\u003c/em\u003e-quinone via carbonyl group [52]. The interaction between the macroradical and MQ will result in the formation of phenoxyl radicals, which further engage in the S\u003csub\u003eH\u003c/sub\u003e2-substitution reaction at the boron atom. The reactions proceed at a very high rate\u0026nbsp;(\u003cem\u003ek\u003c/em\u003e ~ 10\u003csup\u003e6\u003c/sup\u003e-10\u003csup\u003e8\u003c/sup\u003e L∙mol\u003csup\u003e\u0026ndash;1\u003c/sup\u003e∙s\u003csup\u003e\u0026ndash;1\u003c/sup\u003e) [53]. The resulting macromolecules with an aryloxyborane terminal group are capable of reversible homolytic dissociation, reinitiating the polymerization process (Scheme 5) [25]. In the case of low molecular weight \u003cem\u003ep\u003c/em\u003e-quinones (2,3-dimethyl-1,4-benzoquinone, menadione, 1,4-naphthoquinone, and duroquinone), the dissociation of such macromolecules is described by equation:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\"\u003e\u003c/p\u003e\n\u003cp\u003eThus, introduction of PLA chains in DHBQ may allow the preparation of hybrid copolymers. In the first step, the lactide polymerization in the presence of AcONa and DHBQ was studied. At a component ratio [LA]/[AcONa]/[DHBQ] = 100/1/1 at 110 \u0026deg;C, polymerization is completed in about 40 hours (Fig. 1a).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIncreasing the temperature to 120 \u0026deg;C promotes a regular increase in the polymerization rate. The linear dependence ln([M]\u003csub\u003e0\u003c/sub\u003e/[M]) \u003cem\u003evs\u003c/em\u003e conversion indicates the constant number of reaction centers in the polymerization process (Fig. 1b). This fact indicates the first order of the chain growth reaction in terms of monomer concentration. Also, this fact is the sign of controlled polymerization. The polymers\u0026rsquo; molecular weight increases uniformly with increasing conversion (Fig. 1c). The polymers obtained at 110 \u0026deg;C are characterized by the coincidence of \u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e values with those calculated theoretically by equation:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\"\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003ewhere [LA]\u003csub\u003e0\u003c/sub\u003e is initial lactide concentration, [DHBQ]\u003csub\u003e0\u003c/sub\u003e is initial DHBQ concentration, \u003cem\u003eM\u003c/em\u003e(LA) is molar weight of LA (144 g ∙ mol\u003csup\u003e\u0026ndash;1\u003c/sup\u003e) and \u003cem\u003eM\u003c/em\u003e(DHBQ) is molar weight of DHBQ (140 g ∙ mol\u003csup\u003e\u0026ndash;1\u003c/sup\u003e). Only at deep conversions (above 80 %), a positive deviation from the theoretical data is observed. Increasing the temperature leads to a pronounced deviation of \u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e from the linear dependence already at moderate conversions (Fig. 1c). Similar deviations appear on the \u003cem\u003eM\u003c/em\u003e\u003csub\u003ew\u003c/sub\u003e/\u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e \u003cem\u003evs\u003c/em\u003e conversion curve. In general, the synthesized PLA polydispersity remains relatively low (\u003cem\u003eM\u003c/em\u003e\u003csub\u003ew\u003c/sub\u003e/\u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e = 1.13-1.23). Increasing the polymerization temperature leads to broadening of the molecular weight distribution. GPC traces shift uniformly to the region of higher molecular weights with increasing conversion (Fig. 1d). Nevertheless, at deep conversions, a shoulder peak is registered on the GPC-curves. Its presence is related with the trans-esterification process. As the polymerization temperature increases up to 120 \u0026deg;C the bimodality of the molecular weight distribution curve becomes more evident (Fig. 1S). Increasing the concentration of AcONa in the initial feed promotes an increase in the polymerization rate and a decrease in the molecular weight limit achieved (Table 1). The MW dispersion remains low-to-moderate (\u003cem\u003eM\u003c/em\u003e\u003csub\u003ew\u003c/sub\u003e/\u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e = 1.13-1.27) irrespective of the component ratio.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1.\u003c/strong\u003e ROP of LA in the presence of AcONa and DHBQ at 110 \u0026deg;C.\u0026nbsp;\u003c/p\u003e\n\u003cdiv align=\"Left\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e[LA]/[AcONa]/[DHBQ]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eTime,\u0026nbsp;h\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eConversion, %\u003cem\u003e\u003csup\u003ea\u003c/sup\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cem\u003eM\u003c/em\u003e\u003csub\u003en, theo\u003c/sub\u003e \u0026middot; 10\u003csup\u003e\u0026ndash;3\u003cem\u003eb\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cem\u003eM\u003c/em\u003e\u003csub\u003en, GPC\u003c/sub\u003e \u0026middot; 10\u003csup\u003e\u0026ndash;3\u003cem\u003ec\u003c/em\u003e\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cem\u003eM\u003c/em\u003e\u003csub\u003ew\u003c/sub\u003e/\u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e\u003cem\u003e\u003csup\u003ec\u003c/sup\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e50/1/1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e89.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e6.61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e6.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1.27\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e100/1/1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e86.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e12.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e13.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1.21\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e200/1/1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e75.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e21.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e19.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1.18\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e300/1/1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e60.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e26.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e23.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1.17\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e400/1/1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e45.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e26.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e24.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1.13\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e500/1/1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e39.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e28.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e26.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1.15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cem\u003e\u003csup\u003ea\u003c/sup\u003e\u003c/em\u003e\u003csup\u003e\u0026nbsp;\u003c/sup\u003eDetermined by \u003csup\u003e1\u003c/sup\u003eH NMR; \u003cem\u003e\u003csup\u003eb\u003c/sup\u003e\u003c/em\u003e Calculated according to eq. (2); \u003cem\u003e\u003csup\u003ec\u0026nbsp;\u003c/sup\u003e\u003c/em\u003eDetermined by GPC in THF.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eExamination of polymer end groups by MALDI-TOF confirmed the supposed ring-opening polymerization mechanism. According to MALDI-TOF data, all macromolecules have a DHBQ unit (Fig. 2), i.e. they can be attributed to MQ. Since the mobility of hydrogen atoms at OH-groups in DHBQ is relatively high, we believe that both functional groups are involved in the polymerization almost simultaneously. In the area of high molecular masses the MALDI-TOF spectrum shows some peaks corresponding to esterification products (they are highlighted in red rectangle). The analysis of PLA obtained at 120 \u0026deg;C showed that the intensity of the peaks corresponding to trans-esterification products is significantly higher (Fig. 2S). This is in good agreement with the data obtained by the GPC method. Thus, with increasing polymerization temperature, the trans-esterification process becomes more visible that affects negatively the polymers\u0026rsquo; polydispersity.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTo prove the presence of DHBQ unit in macromolecules the \u003csup\u003e1\u003c/sup\u003eH NMR, IR and UV-VIS spectroscopy studies were carried out. According to FT-IR data, the polymer has two types of carbonyl groups whose stretching vibrations are located at 1760 and 1659 cm\u003csup\u003e\u0026ndash;1\u003c/sup\u003e. They belong to the monomer and DHBQ linkages, respectively (Fig. 3a). Due to a yellow coloring of MQ, the UV-VIS spectroscopy can be successfully applied for analysis. Absorption band of MQ (315 nm) is shifted to the short-wave region relative to the initial DHBQ (390 nm, Fig. 3b). With increasing of the length of polymeric chains in MQ the coloration becomes less intense. The appearance of the hypsochromic shift indicates a changing the nature of the substituents in the DHBQ molecule. Similar changes were observed earlier, while studying the inhibited polymerization of methyl methacrylate [54]. The \u003csup\u003e1\u003c/sup\u003eH NMR spectrum of PLA contains peaks that correspond to the end alcohol groups of macromolecules (Fig. 3c). The signals related to the protons of the quinone ring are registered at 6.08 ppm. The analysis of the signal of the PLA methine group indicates the epimerization in the polymerization process. The process temperature variation has little effect on the polymer\u0026rsquo;s tacticity. In view of the overlapping peaks corresponding to different triads, it is impossible to calculate the probabilities of \u003cem\u003eP\u003c/em\u003e\u003csub\u003em\u003c/sub\u003e and \u003cem\u003eP\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e. In general, the resulting MQ can be classified as a heterotactic polymer.\u003c/p\u003e\n\u003cp\u003eThus, under the action of AcONa/DHBQ system PLA with well-defined molecular weight characteristics containing a \u003cem\u003ep\u003c/em\u003e-quinone fragment in the polymer chain was obtained. The presence of the internal quinone unit opens the possibility for further PLA modification by block copolymerization with vinyl monomers.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; It is known that the radical styrene polymerization in the presence of the TBB/\u003cem\u003ep\u003c/em\u003e-quinone system proceeds by the reversible inhibition mechanism [25]. Macromolecules with terminal aryloxyborane groups are responsible for the dissociation-recombination process. Formation of such terminal groups is the result of a sequence of inhibition and subsequent S\u003csub\u003eH\u003c/sub\u003e2-substitution reactions (Scheme 5). Re-initiation of radical polymerization is characterized by the activation energy \u003cem\u003eE\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e = 113.3 kJ ∙ mol\u003csup\u003e\u0026ndash;1\u003c/sup\u003e [25]. The TBB/p-quinone system is similar to the widely used alkylborane/air oxygen system. But due to the absence of uncontrolled borane autoxidation, a higher degree of radical polymerization control is achieved. A wide range of (co)polymers, including hybrid polymers, were obtained using the TBB/\u003cem\u003ep\u003c/em\u003e-quinone system. To obtain PS/PLA copolymers in the presence of TBB, MQ was used as an inhibitor of styrene polymerization.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAIBN-initiated polymerization of styrene at 80 \u0026deg;C in THF in the presence of MQ and TBB proceeds at a moderate rate (Fig. 4a). During the process the MQ loses its coloring due to the conversion of its quinoid structure to an aromatic one. This process is manifested by the disappearance of the absorption band at 315 nm. The linear dependence of ln([M]\u003csub\u003e0\u003c/sub\u003e/[M]) \u003cem\u003evs\u003c/em\u003e time indicates the controlled radical polymerization (Fig. 4a). The block copolymers are characterized by linear growth of \u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e with conversion as well as moderate polydispersity values (Fig. 4b). With increasing conversion depth the molecular weight distribution curves are shifted to the area of higher molecular weights (Fig. 4c). On the GPC curve corresponding to the initial conversion copolymer there is a \u0026quot;shoulder\u0026quot; coinciding with the MQ curve. This fact indicates the slow consumption of MQ in the polymerization process. With increasing conversion the shoulder height is decreasing and after reaching the conversion of 17.6 % this peak disappears completely.\u0026nbsp;Based on GPC data the MQ can be described as a weak inhibitor of radical polymerization. With decreasing MQ concentration in the reaction feed a regular increase of polymerization rate, of copolymer molecular weight as well as of polydispersity were observed (Fig. 4d). Increasing the concentration of TBB in the initial feed does not affect the polymerization kinetics and molecular weight characteristics.\u0026nbsp;This fact corresponds to the polymerization scheme, according to which the limiting stage is inhibition. In addition, the presence of air oxygen traces cannot contribute to the polymerization start, since styrene is not sensitive to the alkylborane/air oxygen system [1].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe copolymers\u0026rsquo; composition was analyzed by \u003csup\u003e1\u003c/sup\u003eH nuclear magnetic resonance spectroscopy. The NMR spectrum clearly shows the signals corresponding to LA and styrene units (Fig. 5a). As the degree of conversion increases, enrichment of the copolymer with styrene fragments is observed (Fig. 4b). The formation of equimolar composition copolymers is observed when the conversion rate reaches 15 %.\u0026nbsp;In addition to the reactions presented in Scheme 5, recombination of macroradicals leading to the homopolymer formation cannot be excluded. To separate the hybrid copolymer from the homopolymer an extraction in a Soxhlet apparatus was carried out. After 40 h, 8.10 wt. % of polystyrene was isolated from the extractant solution, which was identified by IR spectroscopy (Fig. 4S). The grafting degree of 91.9 % was calculated according to equation (3).\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cimg src=\"data:image/png;base64,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\"\u003e\u003c/p\u003e\n\u003cp\u003eDSC study of the hybrid copolymers showed the presence of two glass transition temperatures (\u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e) corresponding to PLA and PS blocks (Fig. 5b). The glass transition of PLA synthesized in the presence of AcONa and DHBQ is observed at 55.6 \u0026deg;C. In the hybrid copolymer the \u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003c/sub\u003evalue of the PLA block is increased in 7.7 \u0026deg;C. In contrast, the \u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e of the PS block decreases by 7.5 \u0026deg;C relative to the homopolystyrene, which is characterized by \u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e = 100.1 \u0026deg;C. These deviations can additionally confirm the fact of copolymer formation. The different nature of the hybrid copolymer blocks is reflected in the physical and mechanical properties. , In contrast to PS synthesized by conventional radical polymerization the MQ synthesized in this work exhibits pronounced elastic properties (Table 3). The hybrid copolymer is also characterized by small \u003cem\u003eE\u003c/em\u003e modulus and large strains (up to 387 %). However, the introduction of 38 % PS allows increasing the \u003cem\u003eE\u003c/em\u003e modulus by 4 times and reducing the strain value by 149 %.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3.\u003c/strong\u003e Mechanical properties of (co)polymers\u0026nbsp;\u003c/p\u003e\n\u003cdiv align=\"center\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003ePolymer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eTensile strength, MPa\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eDeformation, %\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eE modulus, MPa\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003ePS\u003csup\u003e1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e17.6\u0026plusmn;2.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e7.41\u0026plusmn;0.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e2.37 ∙ 10\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eMQ\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.87\u0026plusmn;0.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e536\u0026plusmn;44.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1.62\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003ePS/PLA\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e2.60\u0026plusmn;0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e387\u0026plusmn;65.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e6.73\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003csup\u003e1\u003c/sup\u003ePS prepared by conventional radical polymerization, \u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e = 50,000; \u003csup\u003e2\u003c/sup\u003ePrepared using AcONa and DHBQ: [LA]/[AcONa]/[DHBQ] = 100/1/1, \u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e = 15,800 kDa; \u003csup\u003e3\u003c/sup\u003ePLA mole fraction is 62 mol %, \u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e = 25,800.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThus, an original method of styrene and PLA copolymerization using TBB and DHBQ leading to the hybrid copolymer formation has been proposed. The AcONa/DHBQ system is demonstrated to promote the controlled PLA synthesis, which is confirmed by the analysis of polymerization kinetics, linear dependence of \u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e with conversion and low polydispersity values. MALDI TOF, FT-IR, UV-VIS and \u003csup\u003e1\u003c/sup\u003eH NMR data clearly indicate the presence of DHBQ fragment in the polymer chain.\u0026nbsp;The synthesized PLA can be described as macroquinone capable of mediating radical styrene polymerization in the presence of TBB. Styrene polymerization in the presence of TBB/MQ leads to the formation of a hybrid copolymer with distinct molecular weight characteristics.\u0026nbsp;The small homopolymer content in the copolymerization product positively characterizes this process from the point of selectivity. The introduction of styrene to the copolymer allows increasing the \u003cem\u003eE\u003c/em\u003e modulus and reducing the strain value. Undoubtedly, the proposed synthetic route is comparable to the already known approaches based on RAFT and ATRP. At the same time, it has a number of features and enriches the fruitful chemistry of organoboranes in the field of macromolecular design.\u0026nbsp;\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding and/or Conflicts of interests/Competing interests\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by Ministry of Education of the Russian Federation (No. 073-00034-23-00).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eFurukawa J, Tsuruta T, Inoue S (1957) Triethylboron as an initiator for vinyl polymerization. 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Russ Chem Bull 53:2209\u0026ndash;2214. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11172-005-0101-2\u003c/span\u003e\u003cspan address=\"10.1007/s11172-005-0101-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Schemes ","content":"\u003cp\u003eSchemes 1-5 are available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-polymer-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jpol","sideBox":"Learn more about [Journal of Polymer Research](https://www.springer.com/journal/10965)","snPcode":"10965","submissionUrl":"https://www.editorialmanager.com/jpol/","title":"Journal of Polymer Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"p-quinone, polylactide, polystyrene, copolymers, tributylborane","lastPublishedDoi":"10.21203/rs.3.rs-3821429/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3821429/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study focuses on preparation of hybrid block copolymers of polylactide (PLA) and polystyrene (PS) involving 2,5-dihydroxy-1,4-benzoquinone (DHBQ) as a dual initiator. At the first stage in the presence of AcONa 2,5-dihydroxy-1,4-benzoquinone opened the lactide ring resulting in the carboxylic end-group that further provides for the PLA chain growth. The polymerization proceeds at a moderate rate to high conversion degrees to form the polymers with well-defined molecular weight (MW) characteristics. The presence of an internal DHBQ fragment in the polymer was proven by IR, UV-VIS, NMR and MALDI-TOF techniques. Obtained polymer can be considered as macroquinone (MQ). The styrene polymerization initiated by MQ/Bu\u003csub\u003e3\u003c/sub\u003eB proceeds at a moderate rate leading to the formation of hybrid three-radial PLA/PS copolymer. During the copolymer formation linear increase of \u003cem\u003eM\u003c/em\u003e\u003csub\u003en\u003c/sub\u003e with conversion as well as polydispersity decrease were observed. As evidenced by relatively low content of polystyrene in the copolymer (8.1 wt. %), the process has a good selectivity. The introduction of styrene units into the copolymer allows a 4-fold increase the \u003cem\u003eE\u003c/em\u003e modulus in comparison with the homo-PLA. \u0026nbsp;\u003c/p\u003e","manuscriptTitle":"Three-Arms PLA/PS Copolymer Based on 2,5-Dihydroxy-1,4-Benzoquinone","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-01-24 18:48:08","doi":"10.21203/rs.3.rs-3821429/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2024-02-06T04:12:10+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-01-19T04:07:09+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Journal of Polymer Research","date":"2024-01-07T19:43:34+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-01-02T09:59:50+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Polymer Research","date":"2024-01-02T03:56:08+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-polymer-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jpol","sideBox":"Learn more about [Journal of Polymer Research](https://www.springer.com/journal/10965)","snPcode":"10965","submissionUrl":"https://www.editorialmanager.com/jpol/","title":"Journal of Polymer Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"0d447756-f758-414d-9d90-8477f208d066","owner":[],"postedDate":"January 24th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-06-19T00:35:24+00:00","versionOfRecord":{"articleIdentity":"rs-3821429","link":"https://doi.org/10.1007/s10965-024-04040-1","journal":{"identity":"journal-of-polymer-research","isVorOnly":false,"title":"Journal of Polymer Research"},"publishedOn":"2024-06-18 00:35:24","publishedOnDateReadable":"June 18th, 2024"},"versionCreatedAt":"2024-01-24 18:48:08","video":"","vorDoi":"10.1007/s10965-024-04040-1","vorDoiUrl":"https://doi.org/10.1007/s10965-024-04040-1","workflowStages":[]},"version":"v1","identity":"rs-3821429","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3821429","identity":"rs-3821429","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}