Influence of Spatial and Topological Heterogeneities on Gel Point and Network Structure

Polymer networks are widely used for applications varying from drug delivery, soft robotics, tissue engineering, to commodity materials. The formation of the network and its transition from a fluid to an elastic solid at the gelation point can be predicted theoretically, however, the effect of spatial and topological heterogeneities on the gel point and the resulting network structure is less understood. We use different methods to generate model networks of crosslinked polymer chains in silico. All networks have the same number of end-functionalized chains and crosslinkers with functionality 4, mimicking tetra-PEG hydrogels. Once formed, we investigate their structure and gel point as function of spatial distribution of crosslinkers and topological defects in the network. We find that inhomogeneous crosslinker distributions and overall increased density have a similar effect and lead to a reduction of primary loops in the network.