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New thermotropic copoly(keto esters) based on 3,4′‐disubstituted benzophenones
Author(s) -
Stagnaro Paola,
Tavella Flavio,
Costa Giovanna,
Valenti Barbara
Publication year - 1997
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.1997.021980818
Subject(s) - thermotropic crystal , liquid crystal , differential scanning calorimetry , polymer chemistry , polyester , condensation polymer , copolymer , thermal stability , chemistry , thermogravimetric analysis , benzophenone , solubility , polarized light microscopy , phase (matter) , materials science , organic chemistry , polymer , liquid crystalline , physics , optoelectronics , optics , thermodynamics
Two isomeric benzophenone derivatives, 3‐hydroxy‐4′‐carboxy‐ and 4‐hydroxy‐3′‐carboxybenzophenone, were synthesized and used to prepare new homo‐ and copoly(keto esters) with some commercial comonomers. Polymerizations were performed both by solution and melt polycondensation methods which affect the inherent viscosity and solubility of the resultant products. Yields were always almost quantitative independently of the synthetic method employed. All the samples exhibited very high thermal stability. Phase behaviour and morphology of the polyesters have been investigated by differential scanning calorimetry (DSC) analysis and optical microscopy. A liquid‐crystalline (LC) phase was observed in most of the specimens containing commercial hydroxy acids in percentages higher than 30 mol‐%, while both homopolymers melt to an isotropic liquid. Preliminary gravimetric sorption experiments, using acetone as a penetrant, were carried out on films prepared from some of the copolymers able to give both isotropic non‐crystalline and nematic LC morphologies. The penetrant sorption was strongly reduced by the presence of the frozen nematic LC phase that behaves similarly to the conventional crystalline ordered state.