Covalent adaptable networks (CANs) incorporate dynamic covalent bonds that undergo rearrangement in response to the application of a particular stimuli. These dynamic systems enable the CAN materials to possess novel properties such as self-healing, recycling, and stress relaxation. In recent decades, various types of dynamic bond rearrangements, such as metal-catalyzed transesterification, Diels-Alder reactions, imine exchange, and addition-fragmentation, have been implemented in CAN materials development. As one type of dynamic covalent bonds, disulfide bonds initiate rearrangements stimulated by heat, light, pH, etc., and consequently, emerge as promising candidates for dynamic materials.<br/><br/>Here, we designed and synthesized disulfide-containing vinyl monomers and further applied them in constructing photo thiol-ene/thiol-Michael polymer networks. Addition of a radical initiator enables photo induced disulfide bond exchange, thus achieving spatial and temporal control over reformation of the basic polymer films. Various types of instruments including FT-IR, NMR, DMA, MTS, tensometer, etc. were employed to characterize and evaluate the performance of these photoresponsive polymers. They exhibited highly efficient stress relaxation behavior with stress reduction of up to 80% in photoplasticity experiments. The application of these CANs in impression imprinting materials was demonstrated. The effect of implementing the disulfide-contained monomers in reducing polymerization shrinkage stress in purely acrylate polymerization was also evaluated.

Photochemical controlled dissulfide based thiol-ene/thiol-Michael covalent adaptable network development and application

253rd National Meeting (2017)

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