Formation of Microporosity in Hyper-Cross-Linked Polymers

Molecular simulations of poly(styrene-co-vinylbenzyl chloride) hyper-cross-linked polymers (HCPs) are prepared using a "virtual synthesis" approach with vinylbenzyl chloride contents ranging from 25 to 100%. The trends in porosity from the simulations are in good agreement with experimental data, where surface areas increase with the degree of cross-linking. In addition to studying the final structures, an advantage of using a simulated polymerization is the ability to examine the evolution of porosity throughout the virtual synthesis. Measures of the surface areas and pore size distributions indicate a gradual formation of pores in the swollen state. Additionally, the extent of pore collapse on moving from the swollen to dried states is shown to depend heavily on the degree of cross-linking. This unique perspective gained from the simulations provides important insight in order to gain a better understanding of the structure-property relationships in HCPs.