Volume 46 Issue 1, January 2014

Itaconic anhydride (IAn) was introduced as a new bio-based monomer for lipase-catalyzed ring-opening addition condensation polymerization (ROACP). ROACP reactions combining three components, IAn, a cyclic anhydride and a diol, produced reactive polyesters involving dehydration. Product polyesters belong to ‘biomass plastics’, which provide with a good example of green polymer chemistry.

We investigated the mechanical properties of polymer network formed from the AB-type crosslink-coupling of prepolymers with ‘different size’ but ‘same functionality’ (size-mismatched Tetra-PEG gels). Our experiments revealed that the elastic modulus, the fracture energy and the ultimate elongation ratio of the size-mismatched Tetra-PEG gels had tendencies similar to those of conventional Tetra-PEG gels. From these results, we conclude that the size-mismatched Tetra-PEG gels have the same degree of homogeneity as the conventional Tetra-PEG gels, and the difference in prepolymer size does not affect the homogeneity.

The gelation speeds and temperatures for decalin and paraffin differed significantly. In decalin, gel syneresis occurred by solvent flow from the gels accelerates crystallization, and dry gel films were prepared. In contrast, in paraffin, many nucleating points appeared immediately, and few syneresis occurred even after quenching to room temperature. To prepare dry gel films, paraffin was blotted with filter paper, and residual paraffin was removed in hexane. However, the small-angle X-ray scattering (SAXS) patterns from both films provided similar profiles indicating large crystalline lamellar stacking ensuring ultradrawing.

A wet-chemical approach using DNA extracted from salmon milt as a template to mass produce Ag nanoparticles was developed. Spherical Ag nanoparticles with a main diameter of less than 10 nm were obtained. The concentration of Ag nanoparticles in the as-produced colloidal suspension was as high as 5.3 × 10⁻² mol l⁻¹. This simple and effective procedure should offer an alternative route to the mass production of Ag nanoparticles for practical applications.

Imidazolium salt-terminated first and second generation poly(amidoamine)-typed polyhedral oligomeric silsesquioxane (POSS)-core dendrimers were prepared. Wide-angle X-ray scattering (WAXS) data for cast films of the imidazolium hexafluorophosphate (PF₆)-terminated first and second generation POSS-core dendrimers reflect the same features that were described for 1-butyl-3-methylimidazolium hexafluorophosphate. Ionic conductivities for the imidazolium bis(trifluoromethanesulfonyl)imide (TFSI)-terminated POSS-core dendrimers were estimated by the ac impedance method after the addition of LiTFSI. Maximum ionic conductivity of 4.03 × 10⁻⁵ S cm⁻¹ at 51 °C was observed for the POSS-core dendrimer of lower generation and less lithium salt addition.

The pH-sensitive peptide-grafted PNIPAm was successfully synthesized. The grafted PNIPAm shows different structures according to pH and temperature. Only above transition temperature and under basic conditions did the grafted peptide chains form a stable β-sheet structure and act as bridging points between the (Leu-Lys)₈-grafted poly(N-isopropylacrylamide) globules, resulting in the formation of a large aggregated body. This multi-stimuli-responsive polymer has a wide range of applications in nanotechnology.

Poly(4-(diphenylamino)benzyl acrylate) (PDAA) as a host photoconductive matrix was used for preparing photorefractive (PR) composite. PR responses were investigated at different wavelength of operating laser. PDAA composite has high sensitivity at 532 nm. A demonstration of dynamic hologram from a real object watched through the PR device was performed even at a low field of 25 V μm⁻¹.

Stimuli-degradable cross-linked polymers were developed by applying both topological linkage and size-complementarity of rotaxane to cross-link structure. Radical polymerization of a common vinyl monomer in the presence of the [3]rotaxane cross-linker gave the corresponding stable cross-linked polymer under ambient conditions. Anion exchange reaction with tetra(n-butyl)ammonium chloride caused the selective and efficient de-cross-linking of the cross-linked polymers to vinyl polymer and axle component of the cross-linker.

Cellulose nanofibers (CNFs) with aspect ratios varying from 30–300 were prepared from wood. Higher aspect ratio CNFs had larger intrinsic viscosity values. The predicted aspect ratios on the basis of rigid rod theory for the lowest aspect ratio CNFs corresponded well with our measured values. However, for higher aspect ratio CNFs, the predicted values did not agree with the experimental values. A comparison of the CNF intrinsic viscosities with other types of particles and polymers indicated that the CNFs are semi-flexible rods rather than rigid rods.

Melt mixing of high-density polyethylenes and wheels of perpentylated pillar[5]arenes resulted in formation of polypseudorotaxane structures. Formation of the polypseudorotaxane structures led to extension of the high-density polyethylene chains, and dramatically increased the melting point of high-density polyethylene from 126 to 152 °C. We demonstrated molten state-to-solid and solid-to-molten state transitions of high-density polyethylene based on the host–guest system.

The strongly acidic sulfonated crosslinked polystyrene cation-exchange resins employing divinylnaphthalene or divinylbiphenyl as the crosslinking reagent have been prepared. Their properties in terms of the production of bisphenol-A from phenol and acetone were examined in comparison with the corresponding resin consisting of divinylbenzene. It has been found out that the high conversion of acetone can be obtained even after 150 days of reaction time, which is mainly due to the large space inside the structure of the resins developed here.

Influence of the molecular weight on the thermally enhanced photoinduced molecular reorientation of photo-cross-linkable liquid crystalline polymer films was investigated, where axis-selectively photoreacted side groups controlled the reorientation. Sufficient molecular reorientation (S>0.7) was achieved when the number-average molecular weight (M_n) was >1.8 × 10⁴, but reorientation ability was inferior when M_n was less than 1.0 × 10⁴. The efficiency of the molecular reorientation depended on both degree of the photoreaction and the molecular weight of the material, which is related to the insolubility of the photoreacted film.