Macromolecular Crystal Engineering Based on Segmented Polymers: Influence of Heteroatoms on the Thermal Properties and Crystallization of m,n‐Polyurethanes Derived from Long‐Chain, Heteroatom‐Containing, Monodisperse α,ω‐Diols

Long-chain heteroatom-containing telechelic diols with 29-32 atoms in the backbone were synthesized by a one-step, free-radical tetomerization of 10-undecene-1-ol with commercially available α,ω-dithiols. The oxygen and sulfur atoms caused a decrease in the melting point and enthalpy of the diols, compared to the corresponding purely aliphatic diols. The heteroatom-containg α,ω-diols HO-(CH 2 ) 11 -S-(CH 2 ) 2 -X-(CH 2 ) 2 -S-(CH 2 ) 11 -OH, where X = CH 2 , O, or O-(CH 2 ) 2 -O, were reacted in the melt with 1,6-diisocyanatohexane O=C=N-(CH 2 ) 6 -N=C=O, producing a series of polyurethanes containing an increasing amount of heteroatoms. Characterization by differential scanning calorimetry, infra-red spectroscopy, thermogravimetric analysis, and wide angle x-ray scattering of the m,n-polyurethane series showed that, like the teletechic diols they were synthesized from, the heteroatoms caused a decrease in the melting point and enthalpy. Howeve, they did not affect either the decomposition temperature or the crystal structure/packing.