Cationic polymerization of p-methylstyrene using various metal chlorides: design rationale of initiating systems for controlled polymerization of styrenes

Abstract

Cationic polymerization of p-methylstyrene (pMeSt) was examined using various metal chlorides as Lewis acid catalysts in dichloromethane. All of the catalysts used produced poly(pMeSt)s in the presence of 2,6-di-tert-butylpyridine (DTBP). However, the polymerization behavior differed depending on the type of metal chloride. The polymerization reactions conducted using SnCl4 and ZnCl2 proceeded in a controlled manner and yielded well-defined polymers, whereas metal trichlorides (for example, AlCl3, FeCl3 and GaCl3) induced uncontrolled polymerization. In addition, the combination of SnCl4 and DTBP allowed the controlled polymerization of styrene (St) and p-chlorostyrene (pClSt). Moreover, this initiating system was efficient for the synthesis of star-shaped poly(pMeSt)s via the arm-first method through the addition of an alkylstyrene-type divinyl compound used as a cross-linking agent. Cationic polymerization of p-methylstyrene (pMeSt) was examined using various metal chlorides as Lewis acid catalysts in dichloromethane. Polymerization using SnCl4 and ZnCl2 in conjunction with 2,6-di-tert-butylpyridine (DTBP) proceeded in a controlled manner in contrast to the reactions with metal trichlorides, including AlCl3, FeCl3 and GaCl3. In addition, the combination of SnCl4 and DTBP allowed the controlled polymerization of less reactive styrenes and the synthesis of star-shaped poly(pMeSt)s through the cross-linking reaction using an alkylstyrene-type divinyl compound.