Dangling bond deflection model: Growth of gel network with loop structure

It has been shown that the closed-loop structure in the model gel networks is responsible for their stiffness. However, the creation of loops has been underestimated in most of the existing kinetic aggregation models [e.g., DLCA (diffusion-limited cluster-cluster aggregation) and derivatives]. A dangling bond deflection (DEF) mechanism is proposed to model the fluctuation of dangling branches or dead ends under thermal excitation. The random deflections of the dangling branches can create loops in the network by forming intracluster bonds, and proceed during both the gelling and aging processes. The resulting DLCADEF networks have extensive loop structure with a negligible number of dangling branches. Its growth kinetics and fractal behavior resemble those of real gels, including volume-invariant gel time and fractal dimension of about 2. The DLCADEF model is the first attempt to model the gel growth with loop formation by the physically realistic fluctuation mechanism. The mechanical properties of the resulting networks will be studied and verified by comparison with real gels.