Well-Controlled Polymerization of Tri-vinyl Dynamic Covalent Boroxine Monomer: One Dynamic Covalent Boroxine Moiety towards Tunable Penta-Responsive Polymer
As predicted by Flory–Stockmayer theory, precise control of polymer architecture, molecular weight, and molecular weight distribution in polymerization of tri-vinyl monomers has been recognized as a considerable challenge in polymer chemistry. Meanwhile, multi-responsive polymers are generally designed by incorporating multiple sensitive moieties together in one polymer chain. However, this strategy suffers from complicated synthesis and the compatibility of these functional moieties. The design of multi-responsive polymer by incorporating only one sensitive moiety is of significant importance. Here, we report the successful well-controlled polymerization of tri-vinyl containing dynamic covalent boroxine (DCB) monomer and utilization of dynamic covalent boroxine (DCB) as side chain building block in the molecular design of multi-responsive polymer. Benefiting from the dynamic characteristics, DCB incorporated polymer exhibits tunable penta-responsive behaviours leading to water, fluoride ion, acid and base responsive/sensory, and lower critical solution temperature type thermo-responsive properties that cover a wide temperature range with both solution-colloid transition and sol-gel transition observed. The utilization of only one DCB moiety in the design of 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.