Abstract: Polycarboxylate-type superplasticizers(PC) is an indispensable component of high performance concrete. In this paper, maleic anhydride (MAH), acrylic acid (AA) and methyl allyl polyoxyethylene ether (TPEG) were used as monomers to synthesize maleic anhydride polycarboxylate superplasticizers(MAHPC) by aqueous solution free polymerization. These copolymers were characterized by IR and GPC and the molecular structure of MAHPC was the comb structure with long side chain. The results reveal that the decrease of COO-concentration in MAHPC results in the decrease of the adsorption capacity on the cement surface and the properties of cement paste when the MAH substitution for AA is increased. MAHPC had a good retardation effect on the cement slurry, so the cement slurry still had good workability after 3h flow loss. In the alkaline slurry, the COO-of MAHPC was adsorbed on the cement and cement hydrate as an anchor group. The long side chains of MAHPC had the synergistic effect of steric hindrance and electrostatic repulsion, which helps to disperse the cement.

Key words: maleic anhydride, polycarboxylate superplasticizer, synthesis, hydrolysis, charge density, adsorption

摘要： 聚羧酸减水剂（PC）是现代高性能混凝土不可或缺的组分，本文以马来酸酐（MAH）、丙烯酸（AA）、甲基烯丙基聚氧乙烯醚（TPEG）为单体，采用水溶液自由聚合的方法合成马来酸酐聚羧酸减水剂（MAHPC）；实验通过IR及GPC对减水剂分子进行相应的结构性能表征，明确了MAHPC的分子结构为带有长侧链的梳状结构。实验结果表明：随着MAH对AA替代量的增加，MAHPC分子中的COO–浓度减小，从而在水泥颗粒表面的吸附量减小，对水泥浆体的分散性能减弱；MAHPC对水泥浆体具有较好的缓释性，经过3h流动度损失后，水泥浆体仍有良好的工作性；MAHPC分子中的COO–浓度对水泥浆体的流动度有直接影响，在碱性环境的水泥浆体中，MAHPC中的酸酐键水解生成COO–，COO–作为锚固基团，吸附于显示正电性的水泥颗粒及水泥水化物上，发挥其烷氧基长侧链的空间位阻和静电斥力效应，两者协同达到分散水泥颗粒的作用。

关键词: 马来酸酐, 聚羧酸减水剂, 合成, 水解, 电荷密度, 吸附