ISSN:
0098-1273
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
A homologous series of polyesters was prepared from 4,4′-dihydroxybiphenyl and dibasic acids having 5-12 methylene units. The mesophases formed at elevated temperatures were studied by differential scanning calorimetry and polarized light microscopy. This family exhibits an unusual odd-even effect when the transition temperatures are plotted as a function of the number of methylene units in the dibasic acid. Not only do the points for odd and even members fall on different curves, but the odd members exhibit a nematic phase over a very short temperature interval, while the even members form a highly ordered smectic phase. For both the odd and even series, the transition temperatures are significantly depressed when the inherent viscosity falls below 0.2 dL/g. The largest depression occurs for the crystal melting transition, so that polymers of low ηinh show anisotropic and biphasic regions over wider temperature ranges. A copolymer formed from an equimolar mixture of sebacic and chiral (+)-3-methyl adipic acid forms a cholesteric phase. Evidently copolymerization destabilizes the smectic phase which would have been expected. The results are discussed in terms of existing theory.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1983.180210712
