A Novel One-step Synthesis Of Polyethylene Glycol Methyl Ether Methacrylate Macromonomer By Inserting Ethylene Oxide Into Methyl Methacrylate

A novel process to synthesize macromonomer polyethylene methyl ether methacrylate (PEGMEMA) was investigated. PEGMEMA was prepared by inserting ethylene oxide into methyl methacrylate directly over special acid-base catalyst. Then, polycarboxylic acid type water-reducers were synthesized using PEGMEMA as chief raw material together with methyl acrylate, methyl acrylamide sodium and methacrylate. Ammonium persulfate as the initiator was used for the aqueous radical polymerization. Moreover, the synthesis conditions of PEGMMEMA were optimized according to the information feedback from the fluidity loss of cement paste of polycarboxylic acid type water-reducers.Compared with other traditional approach to synthesize PEGMEMA, the novel one-pot process to synthesize PEGMEMA is a green chemistry approach with excellent atomic economy characteristics since in this process neither extra reactants are needed nor by-products are produced. But the screening of the catalyst and the polymerization inhibitor and application on the yield of PEGMEMA were main technical difficulties on this task.Among a series of composite oxide catalysts possessing acid-base active sites for catalysizing one step ethoxylation of methyl methacrylate, Al/Mg/Ce composite oxide catalyst has excellent high activity capability. The screening of polymerisation inhibitor showed that the combination of NNSP-1 and acetylacetone was the most effective inhibitor during the reaction process. The product was characterized by FT-IR, ESI-MS, GPC and UV.It was found that the catalyst, Al/Mg/Ce (the molar ratio of Al/Mg 0.70), has the highest activity capability for the PEGMEMA with molar ratio of MMA to EO 20:1. The optimal synthesis conditions were as following: the dosage of catalyst 1.5% of the gross weight, the dosage of polymerisation inhibitor combination of NNSP-1 and acetylacetone 3 and 10.5 of the weight of MMA, the initial pressure 0 and dropping EO while maintaing the pressure of the system of 0.8-0.9 MPa, at the temperature of 140-150 oC.At the same time, polycarboxylic acid superplasticizer was synthesized from PEGMEMA copolymerized with other monomers by aqueous radical polymerization. Through inspecting the technical parameters of the performance of the product, the result showed that while the reaction time controlled in 8 h and the reaction temperature was 80 oC, the mobility of cement paste achieved to the maximum degree. The functional groups of the synthesized superplasticizer were characterized through infrared spectrum, the molecular weight and molecular weight distribution through gel chromatography. Through a series of cement concrete experiment, it indicated that the polycarboxylic acid superplasticizer have good dispersive and dispersive retentivity in low-dosage.