Improving mechanical properties and thermal stability of halogen-free flame retardants using di(hydroxyethyl methacrylate) phosphate and spacers

Improving mechanical properties and thermal stability of halogen-free flame retardants using di(hydroxyethyl methacrylate) phosphate and spacers | 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 Improving mechanical properties and thermal stability of halogen-free flame retardants using di(hydroxyethyl methacrylate) phosphate and spacers A. K. Al-Hamzawi, Zahraa M. Gafil, Hind Shabbani, B. A. Buravov, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9614421/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 8 You are reading this latest preprint version Abstract Three halogen-free phosphate-containing oligoester methacrylates (HFPOEMs) were synthesized, including a monomer without spacers (HFPOEM-1) and spacers incorporating either flexible aliphatic linkages (HFPOEM-2) or rigid aromatic linkages (HFPOEM-3). Structural analyses (FTIR and NMR) confirmed the successful incorporation of phosphate groups and spacer units, while DSC results revealed a processing behavior dependent on the type of spacer, with reactivity decreasing as steric constraints increased. Thermogravimetric analysis showed a significant improvement in thermal stability upon incorporation of the spacer, with the aromatic spacer system exhibiting the highest thermal resistance (T 5 % = 279°C) and char yield (44.3 wt%), attributed to enhanced structural rigidity and carbonization. Physical-Mechanical testing highlighted a distinct structure–property relationship, where the flexible aliphatic spacer markedly improved both tensile strength (49.9 MPa) and elongation at break (7.8%), indicating improved toughness through increased segmental mobility and stress dissipation. Conversely, the aromatic spacer improved strength while limiting ductility due to restricted chain mobility. The results of the Limited Oxygen Index (LOI) show that the samples containing spacers have slightly lower LOI values ​​compared to the sample without spacers, following the order: HFPOEM-1 (LOI = 31.6) > HFPOEM-2 (LOI = 30.5) > HFPOEM-3 (LOI = 29.7). Halogen-free flame retardants phosphate-containing methacrylates synthesis spacers thermal stability mechanical properties Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 19 May, 2026 Reviewers agreed at journal 18 May, 2026 Reviews received at journal 16 May, 2026 Reviewers agreed at journal 08 May, 2026 Reviewers invited by journal 08 May, 2026 Editor assigned by journal 07 May, 2026 Submission checks completed at journal 06 May, 2026 First submitted to journal 05 May, 2026 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. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-9614421","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":641230873,"identity":"6cc4ac9c-2eae-48ac-a0b5-d1b105b0dd16","order_by":0,"name":"A. K. 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Structural analyses (FTIR and NMR) confirmed the successful incorporation of phosphate groups and spacer units, while DSC results revealed a processing behavior dependent on the type of spacer, with reactivity decreasing as steric constraints increased.\u003c/p\u003e \u003cp\u003eThermogravimetric analysis showed a significant improvement in thermal stability upon incorporation of the spacer, with the aromatic spacer system exhibiting the highest thermal resistance (T\u003csub\u003e5\u003c/sub\u003e% = 279\u0026deg;C) and char yield (44.3 wt%), attributed to enhanced structural rigidity and carbonization. Physical-Mechanical testing highlighted a distinct structure\u0026ndash;property relationship, where the flexible aliphatic spacer markedly improved both tensile strength (49.9 MPa) and elongation at break (7.8%), indicating improved toughness through increased segmental mobility and stress dissipation. Conversely, the aromatic spacer improved strength while limiting ductility due to restricted chain mobility. The results of the Limited Oxygen Index (LOI) show that the samples containing spacers have slightly lower LOI values ​​compared to the sample without spacers, following the order: HFPOEM-1 (LOI\u0026thinsp;=\u0026thinsp;31.6) \u0026gt; HFPOEM-2 (LOI\u0026thinsp;=\u0026thinsp;30.5) \u0026gt; HFPOEM-3 (LOI\u0026thinsp;=\u0026thinsp;29.7).\u003c/p\u003e","manuscriptTitle":"Improving mechanical properties and thermal stability of halogen-free flame retardants using di(hydroxyethyl methacrylate) phosphate and spacers","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-05-18 16:58:38","doi":"10.21203/rs.3.rs-9614421/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-05-19T07:33:36+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"329782843830233384449446788063780198263","date":"2026-05-18T05:43:53+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-16T11:09:24+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"20642261411995564778450662852733614027","date":"2026-05-08T06:20:10+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-05-08T04:04:32+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-05-07T12:03:13+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-05-06T19:00:52+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Inorganic and Organometallic Polymers and Materials","date":"2026-05-05T06:02:47+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-inorganic-and-organometallic-polymers-and-materials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"joip","sideBox":"Learn more about [Journal of Inorganic and Organometallic Polymers and Materials](https://www.springer.com/journal/10904)","snPcode":"10904","submissionUrl":"https://submission.nature.com/new-submission/10904/3","title":"Journal of Inorganic and Organometallic Polymers and Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"81230383-43c8-4b43-97e6-aad2f66ef35b","owner":[],"postedDate":"May 18th, 2026","published":true,"recentEditorialEvents":[{"type":"editorInvitedReview","content":"","date":"2026-05-19T07:33:36+00:00","index":26,"fulltext":""},{"type":"reviewerAgreed","content":"329782843830233384449446788063780198263","date":"2026-05-18T05:43:53+00:00","index":24,"fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-16T11:09:24+00:00","index":20,"fulltext":""},{"type":"reviewerAgreed","content":"20642261411995564778450662852733614027","date":"2026-05-08T06:20:10+00:00","index":15,"fulltext":""},{"type":"reviewersInvited","content":"13","date":"2026-05-08T04:04:32+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-05-07T12:03:13+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-05-06T19:00:52+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-18T16:58:38+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-18 16:58:38","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9614421","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9614421","identity":"rs-9614421","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}