SYNTHESIS OF BLOCK COPOLYMERS OF P-METHOXYSTYRENE AND VINYL ETHERS BY THE HYDROGEN IODIDE ZINC IODIDE INITIATING SYSTEM

Amphiphilic or polar-nonpolar AB block copolymers of p-methoxystyrene (pMOS) and vinyl ethers (VE; methyl or isobutyl) were synthesized by the sequential living cationic polymerization initiated with the hydrogen iodide/zinc iodide (HI/ZnI2) system in toluene at -15 and +25 °C. pMOS-VE block copolymers of narrow molecular weight distributions ( {Mathematical expression} = 1.05-1.25; {Mathematical expression} = 6000-16000) were obtained in nearly quantitative blocking efficiency, when methyl or isobutyl VE was polymerized first by HI/ZnI2, followed by addition of pMOS to the resulting living polymer solutions; an additional amount of ZnI2 was required to accelerate the second-phase living polymerization of the less reactive styrenic monomer. Similar block polymerizations in an opposite monomer-addition sequence (from pMOS to VE), in contrast, resulted in mixtures of the desired block polymer and homopolymer of pMOS. © 1990 Springer-Verlag.