Back Cover: Macromol. Chem. Phys. 15/2005

Abstract

Back Cover: Polyethylene can be rendered completely amorphous by inserting regularly spaced gem‐dimethyl defects along the polymer backbone. Frequency of insertion is the deciding factor. For example, placing a gem‐dimethyl defect at each and every 9th carbon (8 carbon run length) yields amorphous polyethylene, whereas the polymer possessing an equivalent defect at each and every 15th carbon (14 carbon run length) crystallizes. Precise placement of these gem‐dimethyl defects along the polymer backbone is accomplished by employing step polymerization chemistry (the ADMET reaction) rather than using traditional chain polymerization techniques. Further details can be found in the Full Paper by J. E. Schwendeman and K. B. Wagener* on page 1461.

Hydroxy-telechelic poly(ethylene-co-isobutylene) as a soft segment for thermoplastic polyurethanes

“…Schwendeman et al reported two PEIBs made by acyclic diene metathesis (ADMET), 24,25 bearing a gem-dimethyl moiety on every 9 th and 15 th carbon along the backbone (T g = −47°C, −42°C respectively); the equivalent IB content of these polymers were 22.2 mol% and 13.3 mol%, respectively. In 1998, Shaffer et al reported the T g of a PEIB (M n = 27 kg mol −1 ) with 24 mol% incorporation of IB from the copolymerization of ethylene and IB to be 8°C higher (T g = −37°C), 23 which was possibly due to the increased running length of ethylene segments along the backbone from this statistical copolymerization.…”