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Polyanhydrides, 6. Thermotropic poly(ester anhydride)s derived from 2,5‐bis(alkylthio)terephthalic acids
Author(s) -
Kricheldorf Hans R.,
Domschke Angelika
Publication year - 1994
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.1994.021950312
Subject(s) - polymer chemistry , differential scanning calorimetry , chemistry , thermotropic crystal , condensation polymer , alkyl , magic angle spinning , thermal stability , terephthalic acid , polymer , liquid crystal , organic chemistry , nuclear magnetic resonance spectroscopy , materials science , polyester , liquid crystalline , physics , thermodynamics , optoelectronics
2,5‐Bis(alkylthio)terephthalic acids (and their acyl chlorides) were prepared by nucleophilic substitution of diethyl 2,5‐dibromoterephthalate with octane‐, dodecane‐ and hexadecanethiol. The poly(ester anhydrides) were obtained by thermal polycondensation of disubstituted terephthaloyl chlorides with silylated 4‐hydroxybenzoic acid and silylated hydroquinone. The resulting polymers were characterized by elemental analyses, inherent viscosities, differential scanning calorimetry (DSC) and wide‐angle X‐ray scattering (WAXS) measurements, optical microscopy and 13 C NMR cross polarization/magic angle spinning (CP/MAS) spectroscopy. These measurements suggest that the disubstituted poly(ester anhydrides) form a sanidic type of layer structure in the solid state. Increasing length of the alkyl substituents favours the formation of ordered paraffin domains between the stacks of the main chains. The stability of these quasicrystalline paraffin domains decreases with increasing mole fraction of the anhydride groups. In contrast to their monosubstituted analogues the disubstituted poly(ester anhydrides) do not form normal nematic melts.