Molecular dynamic simulation of polymer and polymer-oxide nanoclusters

Abstract

Small systems composed of 10 molecules of poly-p-xylylene or a TiO2 cluster (rutile) surrounded by 10 molecules of poly-p-xylylene are modeled via the method of molecular dynamics. The thermodynamic characteristics, structure, and mobility of poly-p-xylylene chains in the model systems are studied in a wide temperature interval (195–995 K) and compared with the corresponding characteristics of a volume phase and an individual polymer chain. With increasing temperature, the mobility of monomer units increases; this process leads to disordering. At high temperatures, there is an evident tendency for loosening and further disintegration of an aggregate into individual chains, which adopt a Gaussian coil shape. These transitions are similar to the transitions of the folded individual molecule of poly-p-xylylene. Introduction of a TiO2 nanoparticle into poly-p-xylylene has a strong effect on the characteristics of the system with short polymer chains, where the adhesion of poly-p-xylylene molecules on the TiO2 surface is accompanied by disordering in the peripheral region.