1965 Volume 38 Issue 10 Pages 1615-1620
The polymerization of (+)-1,3-dimethylbutyl methacrylate and its optically impure (−)-isomer have been carried out through different three initiations:
(1) n-BuLi in toluene at −78°C gave isotactic polymers (DI and LI). (2) Azobisisobutyronitrile at 60°C gave atactic polymers (DA and LA). (3) Photopolymerization in the presence of azobisisobutyronitrile at −35–−50°C gave syndiotactic polymers (DS and LS). The tacticities of the resulting polymers have been deduced from their softening temperatures and their infrared spectra. Optically active polymers have been fractionated from a benzene solution by adding methanol. In the cases of DI and DA, the specific rotation [α]D increased with the molecular weight, while in the cases of DS, LS and LA, [α]D remained constant during the change in molecular weight. The optical rotatory dispersion of the polymers has been measured. Drude’s equation does not hold. In the case of DA, however, a straight line was obtained by Moffitt’s equation, giving −64.3 as the b-values.
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