类聚氨基酸大分子的制备及其减水分散性能

Preparation and Dispersion Properties of Quasi Poly(Amino Acid)Macromolecules

聚羧酸减水剂因为具有掺量低、减水率高及绿色环保等优点备受青睐,但实际应用中却因受到混凝土骨料中泥含量的影响,也常伴有相容性差、减水率低及坍落度损失大等问题。因此,文中从聚合物分子结构设计入手,采用异戊烯醇聚氧乙烯醚(TPEG)与甲基丙烯酸缩水甘油酯(GMA)进行共聚,再利用支链末端功能环氧基团与氨基乙酸(GA)反应制备了类聚氨基酸大分子(PAAs)。采用凝胶色谱和动态光散射对PAAs相对分子质量与其分布以及在水溶液中的聚集形态进行了表征,通过水泥净浆和混凝土实验对PAAs减水分散和抗泥敏感性能进行了研究。结果表明,PAAs在水溶液中以纳米聚集体的形式存在,粒径约30~120 nm,而正是由于PAAs聚集体的空间位阻效应在有效分散水泥颗粒的同时,还能显著阻止混凝土骨料中“泥”(蒙脱土)对PAAs的竞争插层吸附消耗,因而PAAs具有优异的减水分散和抗泥敏感性能,应用前景广阔。

Polycarboxylate superplasticizers(PCEs)behaved outstanding advantages of low dosage,high dispersibility,and environmental friendliness,etc.have already become the most indispensable component in the preparation of concrete especially(ultra)high strength concrete.However,in practical application they are often accompanied with unexpected problems such as poor compatibility,low water reduction ratio and large slump loss which results from too high content of clay in concrete aggregates.In this paper,through precise design of polymer structures,quasi poly(amino acid)macromolecules(PAAs)were prepared by polymerization of polyether macromonomers(TPEG)and glycidyl methacrylate(GMA),and followed with grafting reaction between its functional epoxy groups and glycine(GA).The polymer structures and its aggregation behavior,water-reducing and dispersing properties of PAAs were investigated by gel chromatography(GPC),dynamic light scattering(DLS),net cement slurries fluidities and concrete experiments.The results show that PAAs exist in the form of aggregates in aqueous solution with a particle size about 30~120 nm,and just the steric hindrance effect of PAAs aggregates could adsorb and disperse cement particles effectively,and also accompanied with preventing competitive intercalation adsorption of clay to PAAs.Therefore,PAAs have excellent water-reducing dispersion and clay insensitivity properties,and thus behave broad application prospects.