Synthesis and branching structure detection of long-subchain hyperbranched polymers via pyrene-labelled methodology

Long-subchain hyperbranched polymers (LHPs) are macromolecules with complex topological structures that have been extensively studied by researchers. However, the interior branching structure characterization of LHPs remains a challenging topic. In this contribution, LHPs were fabricated through stepwise growth of anionic polymerized AB2 polystyrene macromonomers bearing one Si–H group and two alkyne groups using a hydrosilylation coupling reaction. By varying the reaction solution concentration, LHPs with diverse weight-average degree of polymerization (Dpw) and branching factors (g’) were obtained. Pyrene moieties were efficiently attached to the obtained LHPs by thiol-yne click reaction, and the fluorescence manners of the pyrene chromophores on the LHPs were investigated. The fraction of residual double alkyne (DA) to total alkynes-fDA was proposed as a new parameter to describe the branching structure perfectness of LHPs. IE/IM to fDA calibration curves were built. fDA can be easily determined by IE/IM obtained from fluorescence tests. This study will offer a feasible method to character branching structure perfectness of complex topological polymers.