Low-Temperature Synthesis of EPEG-Based Superplasticizers: Kinetic Optimization and Structure–Property Relationships

Conventional synthesis of polycarboxylate superplasticizers (PCEs) typically relies on high-temperature processes, posing challenges for sustainable production. Ethylene glycol monovinyl polyethylene glycol ether (EPEG), characterized by the high reactivity of its vinyloxy double bond, offers a promising sustainable alternative for low-temperature synthesis. This study systematically investigates the aqueous free radical copolymerization of EPEG and acrylic acid, identifying a reaction temperature of 20 °C as the kinetic optimum that achieves a macromonomer conversion rate exceeding 95% under ambient conditions. Through the variation in five key process parameters, a clear “synthesis–structure–property” relationship was established, revealing that the weight-average molecular weight (Mw) acts as the pivotal regulator of performance. High-Mw PCEs exhibited superior initial dispersion driven by strong electrostatic repulsion and high adsorption but suffered from poor slump retention due to the rapid depletion of free polymers. Conversely, low-Mw variants, regulated by chain transfer agent dosage, significantly reduced the pore solution surface tension, thereby enhancing wetting ability and workability retention. The optimal synthesis conditions (20 °C, 4:1 acid-to-ether ratio, 2.5% initiator, 1.5% chain transfer agent) yielded PCEs with an ideal balance between initial dispersion and retention. Furthermore, the synthesis demonstrated excellent process robustness with a broad dosing window (>60 min). These findings provide a vital theoretical basis for the robust and low-temperature industrial production of EPEG-based PCEs for sustainable infrastructure materials.