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Amorphous‐Smectic Glassy Main‐Chain LCPs, 1. Poly(ether esters) Derived from Hydroxybibenzoic Acid and ( R , S )‐ and ( R )‐2‐Methylpropane‐1,3‐diol
Author(s) -
del Campo Aránzazu,
Bello Antonio,
Pérez Ernesto,
GarcíaBernabé Abel,
Díaz Calleja Ricardo
Publication year - 2003
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.200290028
Subject(s) - glass transition , mesophase , amorphous solid , ether , diol , materials science , polymer , polymer chemistry , quenching (fluorescence) , phase (matter) , crystallography , phase transition , liquid crystal , organic chemistry , chemistry , thermodynamics , composite material , physics , optoelectronics , fluorescence , quantum mechanics
The synthesis and the characterization of main‐chain liquid‐crystalline poly(ether esters), derived from hydroxybibenzoic acid and ( R , S )‐ and ( R )‐2‐methylpropane‐1,3‐diol, are reported. These polymers show an interesting thermal behavior. They develop mesophases with a slow rate of formation, allowing the easy quenching of the melt into: a) the glassy amorphous state, b) the glassy liquid‐crystalline state, or c) a mixture of both, depending on the thermal treatment. The extent of the transformation and the symmetry of the different phases have been determined by means of calorimetric and X‐ray diffraction methods. Dielectric spectroscopy results provide additional evidence for the detection of distinct glass transitions. The results show that the racemic polymer forms a low‐ordered SmC alt mesophase, while a more ordered phase is obtained in the case of the enantiomerically pure polymer. The comparison of the properties of the different states evidences the special behavior and properties of the glass transition ( T g ) in these polymers. Emphasis is paid to the location of the T g of the liquid‐crystalline state in comparison to the T g of the amorphous state. It is found that the glass transition of the SmC alt glass in R , S ‐PBO3 (the poly(ether ester) derived from hydroxybibenzoic acid and ( R , S )‐2‐methylpropane‐1,3‐diol) appears at lower temperatures than the glass transition of the amorphous state. However, in R ‐PBO3 (the poly(ether ester) derived from hydroxybibenzoic acid and ( R )‐2‐methylpropane‐1,3‐diol), where the more ordered phase is present, the glass transition follows the classical tendency of semicrystalline polymers.