Low-carbon environmentally friendly reverse-phase emulsion synthesis of polyacrylamide and rheological performance studies

Reverse emulsion polymerization is an effective method for synthesizing high-molecular-weight polymers. Herein, isoamyl caprylate was used as a replacement for traditional white oil as the continuous phase, and sorbitan monostearate/polysorbate was used as the emulsion system. When the composite emulsion system exhibited a hydrophilic–lipophilic balance (HLB) value of 5.72, water and isoamyl caprylate formed a super-low-interfacial-tension and stable-interface membrane, thereby affording a stable reverse emulsion with a uniform particle size distribution. By studying the kinetics of the polymerization reaction, high-molecular-weight polyacrylamide spatial network structures (termed RSEs), with molecular weights of ˃18 million, were obtained. Scanning electron microscopy revealed that RSE molecules in the aqueous solution were in a microaggregate state and constituted a three-dimensional spatial network structure. The RSE polymer exhibited good temperature and shear resistances, and in an aqueous solution, it displayed typical non-Newtonian fluid behavior. Oscillatory viscoelastic tests on different concentrations of the RSE polymer demonstrated that G' ˃ G" , indicating that the RSE solution was primarily elastic. This study provides a foundation and theoretical basis for the application of ester compounds in reverse emulsion polymerization. Moreover, it offers a new possibility for replacing white oil and reducing the environmental impacts of polymer production and application.