Effect of the composition ratio of repeating units on the properties of poly(4-vinylbenzocyclobutene-co-styrene): molecular dynamics simulation studies

The design of a random copolymer comprising of 4-vinylbenzocyclobutene (4VBCB) and styrene as repeating units is presented herein. The effect of the 4VBCB to styrene ratio in the copolymer on the dielectric and thermodynamic properties of the materials was investigated using the molecular dynamics simulation technique. A script for the interactive crosslink relaxation method was developed using Perl as the language to control the crosslinking degree of the copolymers. This method was used to construct simulation units to generate highly crosslinked polymer networks from a given set of monomers. Three-dimensional simulation cells were constructed with the help of a computational algorithm and Materials Studio. The dielectric constants of the model were calculated using the existing polymer COMPASS force field by varying the monomer contents. The crosslinking degree was tuned to analyze the material properties. Several thermomechanical properties, such as curing-induced shrinkage, coefficient of thermal expansion, and glass transition temperature, were analyzed, and their dependence on the crosslinking degree was examined. The simulation results revealed that an increase in the crosslinking density resulted in an increase in the dielectric constant and glass transition temperature of the material. The extent of thermal expansion realized decreased under these conditions. The reliability of the simulation results was confirmed by comparing these results with experimentally-obtained results. The theoretically and experimentally obtained results demonstrated a close match within the acceptable error range.