A new polymer network design strategy by sequential crosslinker feeding: Kinetic Monte Carlo simulation by graph representation of the chains

Branching, crosslinking and gelation are powerful tools in polymerizations, because these substantially affect the properties of polymers. Studying branching reactions by computer modeling, such as kinetic Monte Carlo simulation (KMCS), can provide detailed insights in such processes, which are substantial in manufacturing of crosslinked polymers, but these are often inaccessible experimentally. However, proper data storage and chain representation are crucial in such simulations. Here, we prove that graph representation of branched macromolecules is an efficient data storage technique in KMCS of free radical copolymerizations leading to branching. Strikingly, the increasing number of the crosslinker’s addition steps ( y ) increases the gel point considerably up to y =4, but only slightly beyond it. Moreover, the networks’ structure remarkably depends on y due to the growing role of coupling of branched chains in the gelation process. Both the number of branched chains and intramolecular cycles, as important factors in determining the properties of polymer networks, decrease significantly when y >1. These findings enable new ways of designing polymerizations for obtaining polymers with desired branching frequencies and gel point, i.e. crucial parameters for manufacturing processes and material properties of crosslinked polymers and gels, and for advanced applications ranging from coatings to dynamic networks, 3D/4D printing etc.