Kazushige Kojima

Living cationic polymerization of p-methoxystyrene by hydrogen iodide/zinc iodide at room temperature

SummaryCationic polymerization of p-methoxystyrene initiated by HI/ZnI2 in toluene afforded living polymers not only at low temperature (−15°C) but at room temperature (+25°C) as well. The number-average molecular weight of the polymers was directly proportional to monomer conversion and in excellent agreement with the calculated value assuming that one polymer chain forms per unit hydrogen iodide. On addition of a fresh feed of monomer at the end of the first-stage polymerization, the added feed was smoothly polymerized at nearly the same rate as in the first stage; the polymer molecular weight further increased in direct proportion to monomer conversion and was close to the calculated value for living polymer. Throughout these reactions, the molecular weight distribution of the polymers stayed very narrow (¯Mw/¯Mn<1.1). This is the first example of living cationic polymerizations of styrene derivatives that proceed even at room temperature.

Living cationic polymerization of isobutyl vinyl ether initiated by the trimethylsilyl iodide/zinc iodide system

SummaryTrimethylsilyl iodide in conjunction with zinc iodide (Me3SiI/ZnI2) as an initiating system led to living cationic polymerization of isobutyl vinyl ether in toluene at 0 or −40°C or in methylene chloride at −40°C (ZnI2 was dissolved in acetone). The number-average molecular weight of the polymers was directly proportional to monomer conversion and in excellent agreement with the calculated value assuming that one polymer chain forms per unit trimethylsilyl iodide. At room temperature (+25°C), however, the polymerization failed to give perfectly living polymers; the polymer molecular weight was smaller than the calculated value. On addition of a fresh feed of monomer at the end of the polymerization at −40°C, the added feed was smoothly polymerized at nearly the same rate as in the first stage, and the polymer molecular weight continued to increase in direct proportion to monomer conversion. Throughout the reaction, the molecular weight distribution of the polymers stayed very narrow (Mw/Mn< 1.1).

Synthesis of block copolymers of p-methoxystyrene and vinyl ethers by the hydrogen iodide/zinc iodide initiating system

SummaryAmphiphilic 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 (

Living cationic polymerization of isobutyl vinyl ether by hydrogen iodide/Lewis acid initiating systems: effects of Lewis acid activators and polymerization kinetics

\overline M _w /\overline M _n

Living cationic polymerization of 4‐tert‐butoxystyrene and synthesis of poly(4‐vinylphenol) with narrow molecular weight distribution

= 1.05−1.25;

Block copolymers of p-tert-butoxystyrene with isobutyl vinyl ether or styrene derivatives via sequential living cationic polymerization: synthesis of amphiphilic macromolecules with a poly(p-vinylphenol) segment

\overline {\text{M}} _n