POLY 101 |
| The addition reaction of isobutylene (IB), styrene (St) and p-methylstyrene (pMeSt) to living poly(p-methoxystyrene) (PpMeOSt+) obtained using 1-chloro-1-(p-methoxyphenyl)ethane (pMeOStCl)/SnBr4 initiating system in CH2Cl2 from –40 to –0 °C in the presence of 2,6-di-tert-butylpyridine (DTBP) as proton trap was studied. Quantitative crossover to IB, St and pMeSt was observed and changing the temperature and concentrations could control the number of monomer units incorporated per chain before irreversible ion collapse. Competition experiments were used to determine the reactivity ratios, kp/k12, where kp is the propagation rate constant of pMeOSt. Based on the reactivity ratios calculated from the limiting conversions and limiting molecular weights, at –40 °C pMeOSt is 38, 251, 322 and 634 times more reactive than pMeSt, IB, St and p-chlorostyrene respectively. These values are in good agreement with the nucleophilicity parameters reported by Mayr.
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General Papers: Functional Materials
6:00 PM-8:00 PM, Sunday, August 19, 2007 BCEC -- Exhibit Hall - B2, Poster
Division of Polymer Chemistry |