PHASE STRUCTURES, TRANSITION BEHAVIORS, AND SURFACE ALIGNMENT IN POLYMERS CONTAINING A RIGID RODLIKE BACKBONE WITH FLEXIBLE SIDE-CHAINS - 2- PHASE-TRANSITION KINETICS IN A MAIN-CHAIN SIDE-CHAIN LIQUID-CRYSTALLINE POLYESTER/

A series of polyesters consisting of aromatic main-chain backbones and flexible aliphatic side chains with 4-cyanobiphenyl end groups has be en synthesized on the basis of the polycondensation of 2,2'-bis(triflu oromethyl)-4,4'-biphenyldicarbonyl chloride with nyl)phenyoxy]-n-alkox ycarbonyl]}-4,4'-biphenyldiol (PEFBP). As recently reported, for a PEF BP polyester containing eleven methylene units in the side chains, PEF BP(n=11), four different structures have been identified in addition t o the isotropic melt. They are as follows: an orthorhombic crystalline phase (K-O), two triclinic crystalline phases (K-T1 and K-T2) in the high-temperature region, and a nematic phase (N). To further understan d the phase transformation mechanisms involved, in this publication, o verall phase transformation kinetics have been carried out using isoth ermal differential scanning calorimety (DSC) experiments. Special atte ntion has been given to the temperature regions where three phases (K- O, K-T1, and K-T2) exist. It is found that each phase possesses its ow n transformation rates. Three overall transformation rate regions are observed that are separated at temperatures of 95 and 113 degrees C, w hich serve as rate boundaries between these different phases. For the linear growth rates measured by polarized light microscopy (PLM), the growth rate of the K-O phase is difficult to be detected due to its fa st transformation rates. The linear growth rates of the K-T1 and K-T2 phases can, however, be measured. Although these rate regions generall y correspond to the overall transformation rates obtained from DSC, a rate minimum can be observed at 130 degrees C in the linear growth rat e data of the K-T2 phase above 113 degrees C. This minimum is formed d ue to the introduction of a new linear growth rate branch above 130 de grees C. The morphological studies under PLM, transmission electron mi croscopy, and the melting temperature changes using DSC indicate that these two growth rate branches in the K-T2 phase correspond to two kin ds of morphological developments: folded chain spherulites and extende d chain single crystals. Furthermore, the linear growth rates are affe cted more by this morphological change compared to the overall transfo rmation rates.