Dynamic Thiol-ene Polymer Networks Enabled by Bifunctional Silyl Ether Exchange

Dynamic polymer networks bridge the gap between traditional thermoplastics and thermosets, representing an avenue toward sustainable polymer synthesis. In this study, we utilize photoinitiated thiol-ene click chemistry to synthesize dynamic polymer networks through incorporating a series of bifunctional silyl ether alkene cross-linkers in the presence of catalytic p-toluene sulfonic acid. We demonstrate that the viscoelastic properties of the material, represented by its stress relaxation time constant, can be manipulated by up to 3 orders of magnitude by simple modifications in catalyst loading, amount of silyl ether cross-linker present, and/or dynamic cross-linker length. Our results show that a nonmonotonic relationship exists between stress relaxation kinetics and cross-linker length. Two representative networks were chosen to illustrate reprocessability under mild temperature conditions. These networks exhibited no loss of mechanical integrity after three reprocessing cycles. The networks can also be fully degraded in the presence of an excess of an acid catalyst.