The supramolecular blend of complementary nucleobase-functionalized ABA triblock copolymers self-assemble into a microphase-separated morphology with enhanced mechanical performance and thermal responsiveness.

Dynamic covalent bonds (DCBs), which can undergo reversible cleavage and reformation upon exposure to readily useable stimuli, have attracted dramatic attention, but the library of such bonds still remains to be developed. Herein, we report molecular structures, dynamic behaviors, and healability of bis­(2,2,6,6-tetramethylpiperidin-1-yl)­trisulfide (BITEMPS-S3) to compare with its disulfide analogue (BITEMPS-S2) exchanged at moderate temperature. Unsymmetrical cleavage of trisulfide linkage induced relatively rapid disproportionation to di- and tetrasulfide derivatives. In the bulk, poly­(hexyl methacrylate) networks partially containing the BITEMPS-S3 moiety as a cross-linking point afforded nearly quantitative damage healability only by simple hot pressing at 110 °C under mild pressure. A slightly higher healability of BITEMPS-S2 compared to that of BITEMPS-S3 would be due to the differences in the chain-transfer reaction for the trisulfide linkage during free-radical polymerization rather than thermal exchangeability of the BITEMPS-S3 moiety. Therefore, not only BITEMPS-S2 but also BITEMPS-S3 should be regarded as one of DCBs triggered upon exposure to mild external stimuli.

RAFT polymerization afforded acrylic ABC triblock copolymers with self-complementary nucleobase-functionalized external blocks and a low-Tg soft central block. ABC triblock copolymers self-assembled into well-defined lamellar microphase-separated morphologies for potential applications as thermoplastic elastomers. Complementary hydrogen bonding within the hard phase facilitated self-assembly and enhanced mechanical performance.

This paper describes the synthesis of highly sterically hindered piperidinyl trisulfide with four spirocyclohexyl moieties, bis(2,6-bis[spirocyclohexyl]piperidine-1-yl)trisulfide (BIBSCPS-S3), from commercially available starting materials in short steps and its application as a...