Molecular dynamics simulation of adsorption of polyacrylic acid on surface of dicalcium silicate

The interactions between polyacrylic acid (PAA) and β-dicalcium silicate (110) crystal face were simulated by molecular dynamics(MD)．The results show that the binding energy for the polyacrylic acid polymer with β-dicalcium silicate (110) crystal is negative and increases with the increasing in the degree of polymerization of polyacrylic acid within simulation range, which indicate that the polyacrylic acid can be adsorbed well on the β-dicalcium silicate crystal face. The analysis of various interactions and pair correlation functions of all systems and adsorption conformation chart indicate that binding energies are mainly determined by coulomb interaction. The results of molecular dynamics simulation of carboxyl groups at different positions of polyacrylic acid also differs greatly. The strength of torsion fluctuation of the chain end carboxyl is larger than that of the mid-chain. Both of those indicate that the mid-chain carboxyl’s adsorption with β-2CaO·SiO₂ crystals is firmer than the chain end carboxyl’s adsorption with β-2CaO·SiO₂ crystals, and more effective. Thus, clinker secondary reaction can be inhibited.