Novel thermotropic liquid-crystalline (LC) copolyesters were prepared with three disubstituted (4,4Ј-, 3,4Ј-, and 3,3Ј-) dioxydiundecanol derivatives of terphenyl analogues of 1,3,4-thiadiazole [2,5-diphenyl-1,3,4-thiadiazole (DPTD)], and their optical and electrochemical properties were examined. Their structures were characterized with Fourier transform infrared, 1 H NMR spectroscopy, and elemental analyses. The thermal and mesomorphic properties of the copolyesters were investigated with differential scanning calorimetry measurements, polarized microscopy observations, and X-ray analyses; the data suggested that these copolymers formed LC smectic or nematic phases. The mesomorphic tendency decreased in the following order: 4,4Ј-DPTD and 3,4Ј-DPTD copolyesters Ͼ 4,4Ј-DPTD and 3,3Ј-DPTD copolyesters Ͼ 3,4Ј-DPTD and 3,3Ј-DPTD copolyesters. Solution and solid-state ultraviolet-visible (UV-vis) and photoluminescence spectra indicated that the copolyesters displayed maximum absorbances and blue emissions according to the DPTD unit; the peak maxima of absorption and emission spectra of the copolyesters shifted to lower wavelengths in the aforementioned order for the LC properties. Cyclic voltammetry measurements indicated that the electrochemical band gaps of the polyesters estimated from the onset of reduction and oxidation processes were almost the same as the optical band gaps determined from the solid-state UV-vis spectral data. The DPTD unit enhanced the hole-injection barrier and improved the charge-injection balance in these polyesters.

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Owing to the large contact surface area in geometry, disc-shaped polymer particles and their fascinating properties compared to those of spherical particles have received increasing attention. Although a variety of methods have been developed, fabricating polymer discs in a facile and versatile manner remains a challenge. In this study, we propose a method to fabricate polymer discs by a hot-press process combined with a sacrificial matrix technique, where only aqueous solutions and suspensions are employed. By embedding polymer microspheres in alginate gel, space between the microspheres is created, and thus, the microspheres can be deformed into individual discs after hotpressing near the T g of the polymer. As case studies, polystyrene, poly(L-lactic acid), and poly(D,L-lactide-co-glycolide) microspheres with a wide range of sizes were processed into polymer discs. The choice of sacrificial matrix and the optimal condition for hot-pressing are also discussed. Moreover, the high interfacial adhesion of the prepared discs was verified, including the adhesiveness of polymer discs to the surface of a cover glass under airflow, as well as the enhancement of aggregation for bovine serum albumin-coated polymer discs in the presence of glutaraldehyde. We suggest that the enhanced adhesiveness of polymer discs can improve their performances in both particle-based targeted drug delivery and latex turbidimetric immunoassay.