Chemically Triggered Synthesis, Remodeling, and Degradation of Soft Materials

Abstract

Polymer topology dictates dynamic and mechanical properties of materials. For most polymers, topology is a static characteristic. In this article, we present a strategy to chemically trigger dynamic topology changes in polymers in response to a specific chemical stimulus. Starting with a dimerized PEG and hydrophobic linear materials, a lightly cross-linked polymer, and a cross-linked hydrogel, transformations into an amphiphilic linear polymer, lightly cross-linked and linear random copolymers, a cross-linked polymer, and three different hydrogel matrices were achieved via two controllable cross-linking reactions: reversible conjugate additions and thiol−disulfide exchange. Significantly, all the polymers, before or after topological changes, can be triggered to degrade into thiol-or amine-terminated small molecules. The controllable transformations of polymeric morphologies and their degradation herald a new generation of smart materials.

Template effects of vesicles in dynamic covalent chemistry

“…Michael acceptor 1 has a UV-Vis absorption band at 300 nm which disappears in the less conjugated Michael adduct. [45][46][47] Even in the presence of vesicles, which cause some background scattering, the UV-Vis absorption band of 1 can be used to monitor reaction with a thiol. Fig.…”

Mechanical and structural consequences of associative dynamic cross-linking in acrylic diblock copolymers

“…While associative exchange reactions have been used to transform the architecture of dynamic covalent polymers between linear, lightly cross-linked, and network states, these transformations relied on the addition of competitive nucleophiles. 61 The sensitivity of this vinylogous urethane block copolymer because cross-links restrict segmental mobility. [62][63][64] However, the Tg's corresponding to both the PnBAand PAEAA-rich domains increase after cross-linking, suggesting that significant mixing of the blocks has occurred, positioning vinylogous urethane cross-links in the PnBA-rich domains.…”

Facile Multicomponent Polymerization and Postpolymerization Modification via an Effective Meldrum's Acid‐Based Three‐Component Reaction

“…These interesting reactions could control the transformations of polymers’ morphologies and degradation. [ 2,3 ] Kalow et al. used the Meldrum's acid derivative as a versatile dynamic cross‐linker, which enabled dynamic bond exchange with thiols in silicone networks and resulted in robust vitrimers.…”