Well-controlled polymerization of tri-vinyl dynamic covalent boroxine monomer: one dynamic covalent boroxine moiety toward a tunable penta-responsive polymer

Abstract

As predicted by Flory–Stockmayer theory, precise control of polymer architecture, molecular weight, and molecular weight distribution in the polymerization of tri-vinyl monomers has been recognized as a considerable challenge in polymer chemistry. Multi-responsive polymers are generally designed by incorporating multiple sensitive moieties together in one polymer chain. However, this strategy suffers from issues of complicated synthesis and the compatibilities of these functional moieties. The design of multi-responsive polymers by incorporating only one sensitive moiety is of considerable importance. Here, we report the successful, well-controlled polymerization of tri-vinyl containing dynamic covalent boroxine (DCB) monomer, and utilization of DCB as a side-chain building block in the molecular design of a multi-responsive polymer. Benefiting from dynamic characteristics, the DCB-incorporated polymer exhibits tunable penta-responsive behavior leading to response/sensing of water, fluoride ion, and acid and base, as well as lower critical solution temperature-type thermo-responsive properties, which cover a wide temperature range, and with both solution–colloid transition and sol–gel transition observed. The utilization of only one DCB moiety in the design of the tunable penta-responsive polymer breaks the stimulus record of multi-responsive polymers, and opens up a new avenue in the molecular design and application of functional polymer materials.