Polarized Light Scattering and Synchrotron Radiation Wide-Angle X-ray Diffraction Studies on Smectic Liquid Crystal Formation of Main-Chain Polyester

Abstract

Recent works on polymer crystallization have given considerable attention to the possibility that the crystal phase in the final semicrystalline state could be preceded by transient liquid crystal phases. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] At this aspect, it is interesting to investigate the smectic liquid crystallization process of polymer in which the developments of positional order as well as the orientational one are required. However, the liquid crystallization from the isotropic melt is hardly followed with the conventional scattering techniques which have been applied for the polymer crystallization because it generally takes place close to equilibrium; i.e., it proceeds completely and rapidly even at small supercooling. Recently, we have found that the following main-chain smectic liquid crystalline BB-3(1-Me) polyester shows strong cooling rate dependence of the liquid crystallization temperature. 19

Nonisothermal Model for the Direct Isotropic/Smectic-A Liquid-Crystalline Transition

“…One-dimensional simulations were performed showing that the inclusion of the thermal energy balance corrects the standard Landau-de Gennes predictions of volume-driven growth under shallow quench conditions (5a-b) to experimentally observed [33,34] diffusion-limited growth. Additionally, the effect of incorporating thermal effects in the presence of meta-stable nematic pre-ordering was found to result in non-monotonic acceleration/deceleration/acceleration growth dynamics (6a-b), as observed experimentally [37]. This work sets the basis for further study of non-isothermal effects of the direct isotropic/smectic-A transition where an extended subset of liquid crystal physics present in the transformation is included (1).…”

“…This has been experimentally observed in a smectic polymer liquid crystal which exhibits extremely slow dynamics [37]. The presence of a transient meta-stable nematic phase preceding the stable smectic phase in this polymer liquid crystal was observed under certain quench conditions [38].…”

“…Under standard conditions, meta-stable nematic pre-ordering is not observed, but when the dynamic timescales between nematic/orientational and smectic-A/translational ordering differ greatly, meta-stable nematic pre-ordering is observed and predicted by the model based on eqn. 3 [37,39,43,54].…”

“…The general phenomena of meta-stable states in phase transitions involving dual non-conserved order was theoretically shown over a decade ago [39], but this generalized approach is not suitable for liquid crystal phase transitions (1). A first-approximation of the experimental system [37], taking into account shape kinetics/growth kinetics/texturing (see 1), has been modeled [40] shedding light on some of the nano-scale phenomena resulting in these experimental observations.…”

Thermotropic Phase Behavior of a Liquid‐Crystalline Poly(ether ester) Derived from Hydroxydibenzoic Acid, 2‐Methyl‐1,3‐propanediol and R‐1,3‐Butanediol

“…The thermotropic phase behavior of a liquid-crystalline poly(ether ester) derived from 4 0 -hydroxybiphenyl-4-carboxylic acid and two different spacer diols (2-methyl-1,3-propanediol and R-1,3-butanediol) has been analyzed by differential scanning calorimetry, real time synchrotron X-ray diffraction and solid-state 13 C NMR. It has been found that the polymer develops a smectic mesophase that presents order inside the layers.…”