Volume 46 Issue 10, October 2014

Both chain collapse below the θ-temperature (coil–globule transition) and chain aggregation below the cloud point were studied systematically with dilute solutions of poly(methyl methacrylate) (PMMA) quantitatively by light scattering experiments. Because of slow phase separation of the PMMA solutions in some polar solvents, the chain collapse process was measured without disturbance by the effect of chain aggregation. To examine the structure of a PMMA globule, an effect of temperature perturbation on the globule in the chain collapse process was investigated, and a phenomenon analogous to the memory effect of glassy materials was observed.

Here, the author summarizes recent development of stimuli-responsive synthetic polymers in ionic liquids (ILs) as a novel platform in designing intelligent soft materials. Owing to the versatile structure designability and unique properties of ILs, such as nonvolatility and wide liquid temperature range, soft materials consisting of polymer–IL combinations can be employed under an open atmosphere for long term, and can also permit wide operating temperature and pressure conditions without concern for solvent evaporation that has been a serious drawback of traditional soft materials.

The recent progress of our research on anion-exchange membranes (AEMs) for alkaline fuel cell applications is reviewed. We have designed and synthesized a novel series of poly(arylene ether)-based AEMs with quaternized ammonium groups. The effect of sequence of polymer main chain (random or block) on the AEM properties, especially anion conductivity, is discussed. Fluorenyl groups serve effectively as scaffolds for the ammonium groups. The results imply that the aromatic AEMs are potentially applicable to alkaline fuel cells using hydrogen or hydrazine as a fuel.

This article reviews the design of polymeric functional spaces with microgel-core star polymers and single-chain folding/crosslinked polymers via living radical polymerization for unique functions. Core-functionalized star polymers were prepared by the intermolecular linking of arm polymers with functional linkers/monomers to provide solubilized microgel spaces for active and recyclable catalysis and selective and stimuli-responsive molecular recognition. Single-chain folding and crosslinked polymers were in turn obtained from the self-folding and/or intramolecular linking of amphiphilic random copolymers carrying hydrophilic poly(ethylene glycol) chains and hydrophobic alkyl pendants in water.

Inspired by functional systems in nature, chemists have created a number of intriguing and useful molecular systems from porphyrin derivatives. Of the synthetic porphyrin derivatives developed to date, strapped porphyrins are unique because they have three-dimensional architectures based on a built-in two-dimensional porphyrin molecule. Consequently, the structures of strapped porphyrins can be customized through detailed molecular design, thereby allowing the synthesis of sophisticated molecular systems. Herein, we describe strapped porphyrin-based polymeric systems with a particular focus on molecular design concepts that have led to unique photophysical, electronic and mechanical properties.

We performed the ternary ‘click’ copolymerization (gelation) of bis(butynyl) methylsuccinate, bis(butenyl) methylsuccinate and 3,6-dioxa-1,8-octanedithiol to synthesize a poly(ester-sulfide) gel, which after oxidation using Oxone afforded the poly(ester-sulfone) gel. The synthesized poly(ester-sulfone) gel was anode-selectively deposited on a stainless-steel electrode by electrophoretic deposition although the parent poly(ester-sulfide) gel was not.

The synthesis and characterization of the organic solvent-soluble polymer containing 1,3,4,6,9b-pentaazaphenalene are presented. From the series of the optical measurements and the comparison studies with the model compounds, we investigated the electronic structures through the polymer main chains involving the azaphenalene unit.

A target polymer was synthesized by the oxidation of a poly(arylene sulfide imide), which was readily synthesized by the conventional synthetic route for polyimides. A synthetic route to high-molecular-weight sulfonated poly(arylene sulfone imide), which cannot be prepared via the direct synthesis of a polyimide moiety due to the presence of electron-deficient groups in the monomers, has been developed.

The second virial coefficient of low-molecular-weight polyisoprene (PI) in 1,4-dioxane at 35.3 °C becomes negative and decreases with decreasing molecular weight, showing that attractive interactions occur between the PI segment and the chain-end segment.

Nanomorphology of sterically stabilized polypyrrole-palladium nanocomposite particles has been extensively characterized by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). High-resolution TEM studies revealed that non-spherical nanocomposite particles were produced with a Heywood diameter of ∼30 nm and also confirmed the existence of palladium nanocrystals with a diameter of 5.4 nm within the particles. SAXS studies on aqueous dispersions of the nanocomposite particles confirmed good colloidal stability and revealed 5.0 and 23 nm as average diameters for the Pd nanoparticles and the nanocomposite particles, respectively.

Amphiphilic poly(pseudo-amino acid) containing a nucleobase that was synthesized by coupling an alkynyl-functional nucleobase derivative to the azido-end group PNZHpr_n. DOX-loaded micelles facilitated drug release more effectively in the uptake of DOX than in that of free DOX by HeLa cells.

A new type of hyperbranched aromatic polyetherketone terminated with carboxylic acid group was synthesized by one-step polycondensation of a symmetric AB₂ monomer, 4,4′-(m-phenylenedioxy)-bis(benzenecarboxylic acid), using phosphorous pentoxide/methanesulfonic acid (PPMA) as condensing agent and solvent. By changing the reaction time and the amount of PPMA, M_w can be controlled in the range of 4.2 × 10⁴ to 1.6 × 10⁵. The polymer has been tested as a weak-acid catalyst and shows a certain catalytic activity for the hydrolysis of cellulose to glucose.

Allyl-etherified trehalose (AxT), with a degree of allylation x=6 or 8, was synthesized by the reaction of α,α-D-trehalose and allyl bromide. Thiol-ene photopolymerizations of AxT with pentaerythritol-based tetrathiol (S4P) and isocyanurate-based trithiol (S3I) produced trehalose-incorporated polymer networks (AxT-S4P and AxT-S3I). All of the photo-cured films exhibited high transparency to visible light. The tan δ peak temperatures of A8T-S4P and A6T-S4P were higher than those of A8T-S3I and A6T-S3I. The former S4P-based film demonstrated much higher tensile strength and modulus at room temperature than the latter S3I-based film did.

Suppression of protein adsorption on polymeric interfaces is one of the significant challenges in developing novel biomedical polymers. In this study, the computational design of an antifouling polymer repeat unit is conducted based on a simple approach, whereby the intermolecular affinities between a probe molecule and a polymer repeat unit are evaluated to generate free energy profiles using molecular dynamics simulations. The simplified method affords convenient and theoretical screening of highly antifouling polymer repeat units.

The alternating copolymer containing p-phenylene-ethynylene, 1,2-disubstituted o-carborane and 9,12-disubstituted o-carborane units in the main chain was prepared. Through the Sonogashira–Hagihara coupling, the desired polymer was successfully obtained. The photoluminescence analysis and density functional theory calculation indicated that the copolymer exhibited aggregation-induced emission property by the intramolecular charge transfer from the p-phenylene-ethynylene moiety to the C1–C2 bond of the o-carborane cluster. Thermogravimetric analysis revealed that thermally stable B–C bond enhanced the ceramic yield of the copolymer.