Application of Conformation‐Dependent Cyclization Model to Free‐Radical Crosslinking Copolymerization With Polymeric Divinyl Monomers: Kinetics, Gel Point, Mesh Size and Network Dimensions

ABSTRACT

A recently proposed model that accounts for conformation‐dependent intramolecular crosslinking is extended and applied to investigate free‐radical crosslinking copolymerization where monodisperse polymeric crosslinkers are used. Uniform miniemulsion droplets, each consisting of N _M0 = 2 × 10 ⁵ monomer molecules including a polymeric divinyl monomer, are used for the Monte Carlo simulation. It is shown that the use of a polymeric crosslinker effectively suppresses the primary cyclization that is formed within a single primary chain, and the gel point approaches that predicted by the classical gelation theory. The mesh size of the resulting polymer network is significantly increased compared to that of the low molecular weight crosslinkers. The spatial size of an inhomogeneous network polymer is generally larger than that of a homogeneous random network, since regions of low crosslinking density dominate the size. The use of monodisperse polymeric crosslinkers imparts regularity and reduces the three‐dimensional (3D) size, whereas the conformation‐dependent intramolecular reactions introduce heterogeneity, which contributes to dimensional expansion. The 3D size is determined by the balance between these two opposing effects. The conformation‐dependent cyclization model allows for a detailed analysis of how polymeric crosslinkers alter the network structure and its properties.