Abstract: 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 (1 0) face are significantly stronger than those with (104) face. The binding energies are mainly determined by coulomb interaction 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 (1 0) 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.

Key words: Molecular dynamics, Water-soluble polymers, Calcite, Scale inhibitors, Binding energy, Pair correlation function, Deformation energy