Volume 48 Issue 1, January 2016

In this review, we show that using two-dimensional (2D) samples suitable for atomic force microscopy (AFM) observation, especially Langmuir–Blodgett films, molecular images of various polymer structures could be obtained by tapping-mode AFM. The molecular-level observations included isolated polymer chains and their movements on substrates, 2D folded-chain crystals and their melting behavior, crystallization behavior of single isolated chains, supramolecular multistranded stereocomplex and chain packing in monolayers. The molecular-level information obtained by the direct observations should greatly improve our understanding of polymer science.

Susceptible situation of water molecules in the vicinity of lopsidedly charged copolymer films (upper) and a zwitterionic copolymer film. The charge-neutralized polymer surface is less perturbative to the structure of vicinal water. The image first published in Kobunshi 39, 445 (Hot Topics) (2014).

This review focuses on redox-induced molecular actuation in macromolecular and self-assembled systems. Effective amplifications of conformational changes of unit molecular part are explored on the basis of three categories: polymeric system; molecular interactions; and self-assembled system. The importance of highly ordered structures is suggested to effectively amplify conformational change of small molecular unit into macroscopic deformation of bulk materials. Finally, future outlook toward electrochemical soft actuators and tips to prepare stimuli-responsive molecular assemblies, which undergo amplification in conformational change of constituent molecules, are provided.

Recent developments on bipolar electrochemistry as an effective tool for the fabrication of gradient polymer surfaces were reviewed. The electrochemical doping and reactions of conducting polymers under an applied potential distribution using bipolar electrodes have been carried out to prepare conducting polymers with composition gradients. Indirect electrolysis using an electrogenerated metal catalyst on bipolar electrodes successfully afforded gradually modified polymer surfaces and gradient polymer brushes. The newly designed cylinder bipolar electrode system is available for site-selective applications of electric potentials, which produced electrochemical patterning of conducting polymer films.

The lithography process simulations modeled by coarse-grained polymer techniques are reviewed. As a case of top-down process, development and rinse processes were simulated. From these simulations, line edge structure can be obtained to discuss the line edge roughness. As a case of bottom-up process, the directed self-assembly (DSA) process was simulated, and the polymer chain dynamics in the defect annihilation process can be analyzed.

This Focus Review provides an overview of our recent study and related work on ion conductive polymer nanofibers and their applications in polymer electrolyte fuel cells. We succeeded in evaluating the intrinsic proton and anion conductivity of electrospun nanofibers and revealed their distinguished ion conductive properties, which were quite different from those of the corresponding polymer membranes. These ion conductive nanofibers have potential utility as polymer electrolyte composite membranes to improve fuel cell performance by utilizing efficient ion conduction both inside and at the surfaces of nanofibers.

Because of importance of anions as analyte in diverse fields, a reliable and practical method that allows simple and rapid anion detection has been in increasing demand. To satisfy this requirement, many efforts have been made to develop optical anion sensor materials for sensor applications. This article reviews recent progress in the design and fabrication of conjugated polymer-based anion sensors. Through rational molecular design of the sensor polymers, certain structures have been found to possess desirable anion detection abilities, including enhanced binding affinity, strict size specificity and applicability to anions in an aqueous environment.

Boron-moiety-containing aluminoxanes (BMAOs) were prepared from the partial protonolysis of Me₃Al using various arylboronic acids. Compared with methylaluminoxane (MAO) generated from the hydrolysis of Me₃Al, BMAO prepared from C₆F₅B(OH)₂ and Me₃Al induced a higher activity at the same Al/Ti ratio in the propylene polymerization using ansa-Me₂Si(Flu)(N^tBu)TiMe₂ catalyst. The time course of propylene consumption when using BMAO showed the deactivation of the catalyst. Among the BMAOs, only those derived from arylboronic acids with electron-withdrawing groups were observed to act as efficient cocatalysts.

Hg(II)-imprinted polymers were analyzed by Fourier transform infrared spectroscopy. The spectrum of IIP2, prepared using diphenylcarbazone, showed two additional peaks attributed to the stretching of nitrogen bonded to the aromatic carbon of diphenylcarbazone, not found in IIP1. Comparing leached and unleached IIP2, the peak shape of C=N (1636.3 cm⁻¹) in unleached IIP2 was drastically changed emphasizing the interaction of mercury with nitrogen on 4VP. Moreover, a slight shift of the additional peaks was observed. These results show the possible interaction of mercury ions both with the nitrogen bonded to the aromatic carbon of diphenylcarbazone and the nitrogen of the monomer.

Microbial fermentation system is designed to convert glucose to 4-hydroxyphenyllactic acid (DHPA), an aromatic-containing derivatives of lactic acid. By a methylation, DHPA was transformed to a diol monomer to synthesize bio-based polyesters with benzene rings in their backbone. The polycondensation of DHPA diol was performed with a series of aliphatic diacid chlorides to produce semi-aromatic polyesters with glass-transition temperatures <45 °C. By polycondensation with aromatic diacylchlorides such as terephthaloyl chloride and isophthaloyl chloride, thermally stable DHPA-based polyesters with glass-transition temperatures as high as 130 °C were obtained.

The functionalized polystyrene microspheres containing 3-(trimethoxysilyl) propyl-methacrylate (silane bridging agent) were prepared by dispersion copolymerization, and nickel layers were successfully introduced onto the surface of the microspheres by an electroless plating method. The silane bridging agent makes the nickel layer surface of PS microspheres more compact and uniform in distribution and seems to provide a stronger bond between the metal shell and the polymer core, as well as more adsorption area for Si-O-Ni.

Three new copolymers P1, P2, P3 have been synthesized and characterized. A variety of post-treatments are employed to optimize the performance of solar cells based on these copolymers. A maximum power conversion efficiency (PCE) of 1.22% is achieved by P2 in conventional configuration cells. The PCE of P2 can be further enhanced with inverted configuration, which is ascribe to the more light absorption by TiO₂ nanoparticles and the close energy alignment between the work function of MoO₃ and the HOMO energy levels of P2.

Thiol-ene photopolymerizations of isocyanurate-based trithiol (S3I) / mercaptopropyl-substituted random-type polysilsesquioxane (SQ) and allyl-etherified trehalose (AxT) with a degree of allylation, x = 6 or 8, which was prepared by the reaction of α,α-D-trehalose and allyl bromide, produced trehalose-incorporated organic-inorganic hybrid nanocomposites (AxT-S3I/SQy) with a SQ content, y =10 or 20 (wt%). All of the photo-cured hybrid films exhibited high transparency to visible light. FT-IR spectral analysis revealed the progress of thiol-ene photopolymerization. The thermal properties (glass transition and 5% weight loss temperatures) and mechanical properties (tensile strength and modulus) of the hybrids were much improved by the incorporation of SQ.