Dynamics of 3D polymer gel with reversible linkers

We utilize the gel lattice-spring approach to develop the 3D computational model of polymer gels containing the temporary crosslinks. The polymer chains are assumed to incorporate the folded domains that encompass the reactive functional groups (cryptic sites). Under deformation, the domains unfold and expose the cryptic sites, which can then form labile bonds with the linker chains grafted to the network. Once the deformation is removed, the linkers detach from the cryptic sites, and unfolded domains go back to the folded configuration thus hiding the cryptic sites. The gel behavior under applied force is described by the equations of elasticity of the polymer network coupled to the chemical kinetics equations for the folding and binding transitions. The model equations take into account the effects of finite chain extensibility on the gel elasticity and mechanosensitive reaction rates. Elasticity of the transient network is introduced to the model through the Flory approach. We study the behavior of the system under uniaxial extension and compression, and determine the effect of temporary crosslinks on the bulk and shear moduli of the gel. We also compare the behavior of the gel with a similar gel not undergoing the transient binding of the linker chains.