Volume 50 Issue 6, June 2018

Theoretical models for thermo-sensitive hydrogels in pure water and in mixed solvent of water and methanol, and for thermo-sensitive copolymer in water are developed based on the concept of cooperative hydration of thermo-sensitive water-soluble polymers. The high-temperature collapse in water and the reentrant volume phase transition in water/methanol mixtures of poly(N-isopropylacrylamide) gels, and the phase behavior of statistical random copolymers of N-isopropylacrylamide and N,N-diethylacrylamide are theoretically studied.

This review focuses on recent developments in the study of photosensitive engineering plastics based on reaction development patterning (RDP). RDP is a method of forming a fine pattern by promoting the reaction between carboxylic acid derivatives in a polymer chain and nucleophiles in a developer selectively at the exposed or unexposed area. Since engineering plastics such as polyimide and polycarbonate inherently have carboxylic acid derivative groups, RDP can impart photosensitivity to various polymers, including commercially available engineering plastics. Both positive- and negative-tone patterns can be formed by using RDP.

The influence of poly(butylene succinate) (PBS) crystals on the crystallinity of poly(ethylene oxide) (PEO) in PBS/PEO blends, which exhibit interpenetrating spherulites, was examined. The degree of crystallinity, ϕ, of each component was obtained by pulsed nuclear magnetic resonance (NMR). The dilution effect, order of crystallization, and change in the glass transition temperature upon blending were discussed as factors contributing to the ϕ. PEO exhibited an apparent secondary crystallization, where ϕ gradually increased and the mobility of the chain segments was suppressed. The secondary process of PBS was nearly negligible.

We synthesized side-chain crystalline block copolymer that exhibit an adsorptive interaction with polyethylene (PE) using a monomer with a long alkane side chain and a hydrophilic monomer. By coating PE with a dilute solution of these block copolymers, the PE surface can easily be endowed with hydrophilicity in a uniform manner. This method does not require a special experimental apparatus or reagents and is more viable than conventional methods in terms of energy efficiency and cost, which means it has a lower environmental impact. Based on the measured contact angle on the modified PE surface, we also evaluated the effects of copolymer concentration in the coating solution and the degree of polymerization in the functional region of the copolymer. The results suggest that the hydrophilicity of the PE surface can be controlled by adjusting these parameters.

This study demonstrated convenient preparation methods for the introduction of cationic and cross-linkable moieties into 2-branched and 4-branched PCL and their corresponding stable materials. The cationic content and the ratio of 2-branched and 4-branched monomers could be simultaneously controlled by incorporating non-cationic macromonomers. Zeta potential measurements proved that the cationic charge could be controlled by changing the temperatures. Human MSC adhesion was observed on the PCL materials with different cationic contents and lower contents of cationic contents seem to be preferable. Consequently, such materials are promising for biomaterials research.

Photoinduced molecular switches were achieved by atropisomeric polymers containing conjugated structures of azo and binaphthyl units. trans-cis Photoisomerization of the azo unit led to molecular twisting motion of the binaphthyl unit, yielding chiroptical switching in a neat film. The atropisomeric polymers also displayed photoswitchable fluorescence by repeated irradiation of UV and visible light. Irradiation of the neat film with linearly polarized light caused selective excitation of the atropisomeric polymer, leading to anisotropic molecular orientation.

Novel high-refractive-index materials consisting of poly(thiophosphonate)s were developed by the polycondensation of phenylthiophosphonic dichloride with various bisphenols. These polymers exhibit excellent thermal stability (T_d5 > 420 °C), moderate to high glass transition temperatures (117–204 °C) and high transparency in the visible light region. Furthermore, they achieve high refractive indices of 1.626–1.687 owing to the highly polarizable sulfur and phosphorous atoms in their backbones and relatively high Abbe numbers of 21.3–27.5.