水溶性聚合物与方解石晶体相互作用的MD模拟

用分子动力学(MD)方法, 模拟计算了三种水溶性聚合物阻垢剂聚丙烯酸(PAA)、聚甲基丙烯酸(PMAA)、丙烯酸-丙烯酸甲酯共聚物(AA-MA)]与方解石晶体的作用. 结果表明, 聚合物与方解石两晶面结合能的大小均为PAA ＞ AA-MA ＞ PMAA, 聚合物与(1 0)面的相互作用远比与(104)面的作用强. 对体系各种相互作用以及对关联函数g(r)的分析表明, 结合能主要由库仑作用决定. 与方解石晶面结合的聚合物发生扭曲变形, (1 0)面上的形变能约为(104)面上的2倍, 但均远小于相应的非键作用能. 聚合物中不同位置羧基的动力学行为差别很大, 链端羧基的运动翻转比链中部羧基剧烈得多, 后者与方解石晶体的结合比前者牢固而能更有效地抑制垢晶体生长.

Molecular Dynamics Simulation of Interaction between Calcite Crystal and Water-soluble Polymers

The interactions between three kinds of water-soluble polymers, i.e. polyacrylic acid (PAA),polymethylacrylic acid (PMAA), and acrylic acid-methyl acrylate copolymer (AA,MA), and calcite crystal have been simulated by molecular dynamics (MD). The results show that the orders of binding energies for three polymers with two calcite crystal surfaces are PAA > AA,MA > PMAA, and the interactions of polymers with calcite (110) face are significantly stronger than those with (104) face. The binding energies are mainly determined by coulomb nteraction by analysis various interactions and the pair correlation functions of the systems. Polymers deform during their combining with calcite crystal surfaces, and the deformation energies of polymers on (110) face are about 2 times as those on (104) face, but all of them are far lower than respective nonbonding energies. The dynamics behaviors of carboxyls at different positions of polymer chains are widely different. Carboxyls at the end of chains oscillate more rapidly than those in the middle, so the middle ones hinder scale crystal growth more effectively than the end segments because they combine with calcite crystal more firmly.