Fig. 1: Concept and reaction schemes of the synthesis and degradation of cyclobutene imide-based and cyclobutene carboxylate-based co-polymers and polymer networks.
From: Mechanically triggered on-demand degradation of polymers synthesized by radical polymerizations
a, Schematic representation of conventional C–C main-chain polymers made by radical polymerization that are not degradable under hydrolytic conditions. b, Schematic representation of polymers whose propensity to degrade under basic conditions is mechanically activated. Grey spheres, conventional monomers for radical polymerizations; green spheres, cyclobuten imide-based monomers that can be mechanically activated in the polymer backbone; blue spheres, hydrolyzable imide units in the polymer backbone; red spheres, end-groups of degraded, low-molecular-weight species. c, Synthesis of HCBI, radical homo- and co-polymerization of HCBI, force-induced rearrangement of cyclobutane rings to introduce imide groups into the polymer backbone and co-polymer degradation to small molecules after treatment with 1.0 M NaOH (aq.). d, Synthesis of MCBI, the cross-linker DCBI and polymer networks (PS-co-PMCBI)-l-PDCBI, as well as force-induced rearrangement of cyclobutane rings to introduce imide groups into the polymer backbone and degradation of the cross-linked polymer to small molecules after treatment with 1.0 M NaOH (aq.). e, Synthesis of the cyclobutene carboxylate monomer CBO, radical co-polymerization of CBO and styrene and degradation of the co-polymer to small molecules under grinding without hydrolysis. TFA, trifluoroacetic acid.
