Networks that contain boronic ester crosslinks undergo dynamic bond exchange that enables self-healing behavior and reprocessing.

The design and synthesis of a new class of thermally-labile poly­(β-thioester)­s is reported. Aliphatic azo linkages were incorporated into the main chain of the polymers to allow for degradation to lower molecular weights upon heating. These polymers displayed a temperature-dependent degradation profile with a significant increase in decomposition rate as the temperature was raised from 60 to 95 °C. This approach was further extended to prepare amphiphilic triblock copolymers containing poly­(β-thioester)­s and poly­(ethylene glycol) (PEG). The resulting block copolymers were capable of self-assembly into micelles in water. Moreover, the assembled nanoparticles underwent dissociation as a result of exposure to heat.

Radical copolymerization of divinyl monomers in the presence of chain transfer agents leads to soluble hyperbranched polymers. In this work, hyperbranched poly­(poly­(ethylene glycol) methyl ether methacrylate) (PPEGMA) with degradable cross-linker branch points derived from glucarodilactone methacrylate was prepared via reversible addition–fragmentation chain transfer (RAFT) polymerization to provide insight into hyperbranch formation during copolymerizations of multiolefinic compounds. The number-average molecular weight of the polymers increased nonlinearly with monomer conversion, implying that the incorporation of the divinyl cross-linker led to chain branching and a rapid increase in molecular weight at high conversion. The degree of branching was varied by controlling the feed ratio of monomer to cross-linker to chain transfer agent. Hydrolytic degradation of the sugar-derived dilactone branch points was examined under acidic, neutral, and basic aqueous conditions. To provide fundamental insight into the growth of primary chains during RAFT polymerizations of multiolefinic compounds, the resulting hyperbranched polymers were subjected to cross-link cleavage to obtain linear polymers. The molecular weights of the resulting polymer segments were similar to the theoretical molecular weights expected for linear analogues prepared with similar ratios of monomer to RAFT agent. Not only does this approach lead to new examples of degradable polymers with complex architectures, but also to important mechanistic insights into hyperbranch formation via polymerization of multiolefinic compounds.

A series of Diels–Alder (DA) crosslinked polymethacrylate networks covering a broad range of glass‐transition temperatures (Tg) was prepared to establish the relationship between the Tg and the thermal decrosslinking behavior of these networks. A series of permanently crosslinked and uncrosslinked analogues were also prepared to better understand the thermoset‐to‐thermoplastic transition occurring in the DA networks at elevated temperatures. The network series were studied using dynamic mechanical analysis, which established an inverse relationship between Tg and decrosslinking ability. Differential scanning calorimetry confirmed the viability of the DA linkages in all formulations, and a trapping experiment with 9‐anthracenemethanol demonstrated that even the least responsive network was capable of undergoing decrosslinking given appropriate thermal treatment. While polymer chain mobility has long been understood to be a critical factor in healable materials, this work verifies the importance of this parameter in the decrosslinking of DA networks. © 2019 Wiley Periodicals, Inc. J. Polym. Sci. 2020, 58, 193–203