Chain extension of center-functionalized polystyrene via radical–radical coupling: Periodic introduction of complementary hydrogen bonding interaction site on polymer chain

Abstract In this work, our purpose was directed to syntheses of unique polystyrene (PSt) periodically carrying complementary hydrogen-bonded interaction sites in the chain. First, a bifunctional (bi-headed) initiator carrying three-point complementary hydrogen bonding sites (Cl–DAD–Cl: D = hydrogen donor; A = hydrogen acceptor) was employed for ruthenium-catalyzed living radical polymerization of styrene. Precise control of the polymerization allowed quantitative introduction of the DAD unit at the center and Cl capping group at the terminals for the resultant PSt chain as well as narrow molecular weight distribution. Generation of concentrated radical species from the C–Cl bonds at the both terminals in the absence of monomer induced radical–radical coupling reaction between the styryl radical species for “chain extension”. Since molecular weight distribution of the precursor was enough narrow ( M w / M n