FTIR studies of molecular disorder in long chain n-alkanes: Chain tilt and chain end disorder

Successive heat annealing and cooling of the extended chain form of C198H398 leads to a perfecting of the chains, on the evidence of FTIR data. A similar sample of CD3(CD2)11(CH2)192(CD2)11CD3 allows the deuterated end segments to be analysed separately. It is shown that the end segments develop better register, while the chain interior is scarcely affected by annealing. The alignment of chain ends coincides with the development of chain tilt (from SAXS data), the tilt angle increasing as the chain ends become more defect-free to a figure close to the maximum values obtained for polyethylene.