Self-growth of hydrogels under constraints

Using the 3D gel lattice spring model (gLSM), we explore the effects of boundary and structural constraints (stiff fibers) on polymer gel morphology during growth. During the initial stage of growth (Stage 0), a flat parent gel swells in a solution of monomers and cross-linkers until it reaches equilibrium. The presence of constraints during swelling causes a spatially non-uniform distribution of monomers in the gel sample that leads to buckling of the gel. The actual growth of the gel occurs during Stage 1, when the species, which diffused into the parent gel, undergo polymerization and cross-linking followed by inter-chain exchange to form a random copolymer network (RCN). The resulting RCN gel replicates the shape of the Stage 0 parent network and remains buckled even after the removal of the structural constraints. We explore scenarios of growth with various placements of the structural constraints (fibers). The study could lead to potential applications in fabrication of shape morphing and controlled gradient materials.