Original Article in 2010

Poly(tetramethylsilarylenesiloxane) derivatives having diphenylfluorene (P1) or diphenyldibenzosilole (P2) skeleton were synthesized. The excellent thermal stability of P1 and P2 was confirmed by the differential scanning calorimetry and thermogravimetry. There were differences in the crystallinity between P1 and P2. The fluorescence quantum yield of P2 was higher than those of P1 and the corresponding monomer indicating the decrease in the tendency toward aggregation by use of dibenzosilole skeleton.

By the presence of 100 W ultrasound during extrusion, SiO₂ nanoparticles become smaller and their aggregations disappear, indicating that more homogeneous dispersion of SiO₂ nanoparticles into propylene-based copolymer matrix is achieved.

Polyvinyl alcohol (PVA), which has been used to prevent flaking of paint pigments on traditional Japanese Shohekiga, became white and we investigated its phenomenon. The surface of whitened PVA was irregular and rugged, and many micrometer size cracks were observed. This suggests that efficient scattering of all visible region light from the cracks causes whitening. Fourier transform-infrared spectroscopy and X-ray photoelectron spectroscopy measurements revealed that interchain dehydration and chemical crosslinking (C–O ether linkage) occurred on the surface of whitened PVA.

Dendritic multiarm star block copolymer hyperbranched poly(glycidol)–poly(N-isopropylacrylamide) (HPG–PNIPAM) was prepared by the reversible addition-fragmentation transfer polymerization technique. In aqueous solution, the unimolecular polymeric micelles HPG–PNIPAM have a core-shell nanostructure, with hydrophilic HPG as the core and thermoresponsive PNIPAM as the shell. Dynamic and static laser light scattering measurements show a unimolecular process of reversible phase transition behavior for the unimolecular polymeric micelles in dilute solution.

In the free-radical cross-linking multiallyl polymerization, the structure of network polymer precursor (NPP) consisting of oligomeric primary polymer chains would become core-shell type dendritic or nanogel-like with the progress of polymerization and then, the NPPs can collide with each other to form cross-links among NPPs, eventually leading to gelation. Thus, the dilution of NPP by newly adding monomer could prevent the cross-link formation between NPPs and consequently, lead to the successive growth of NPP from nanogel to microgel.

Oligothiophene-stacked polymers were synthesized by the Suzuki–Miyaura coupling reaction. Oligothiophene units were layered in proximity, ∼3.0 Å from each other. The polymers were characterized by various spectroscopic and electrochemical methods. The polymers have potential application to optoelectronic devices such as hole-transporting materials.

The polymer graded index (GRIN) lens with high impact resistance can be made by easy technique, but the thermal stability is not so excellent. In this study, we propose a new method of fabricating organic–inorganic microcomposite cylindrical GRIN lens. This method is based on spontaneous frontal polymerization technique and diffusion of two organic materials with different refractive indices to an inorganic wet-gel. The obtained microcomposite cylindrical GRIN lenses are not only thermally stable, but also have a controlled refractive index profile due to its inorganic matrix.

Binary catalysts composed of cationic rhodium complexes, [(tfb)Rh(L)₂]X (tfb: tetrafluorobenzobarrelene, L: phosphine ligand, X: counter anion), and ⁱPrNH₂ induced living polymerization of phenylacetylene and its ring-substituted derivatives. The living nature was confirmed by kinetic plots of the polymerization. Nuclear magnetic resonance studies revealed that ⁱPrNH₂ serves to dissociate the coordinating PPh₃ ligand of [(tfb)Rh(L)₂]X to form an initiating species. Block copolymers were synthesized by the sequential polymerization of different phenylacetylenes using the present catalyst.

Recently, polymer matrix-based nanocomposites have become a prominent area of current research and development in optics, optoelectronic, biomedical, electrical and electronic applications. Organic polymer-based electronic devices offer the potential for lower cost and more flexible manufacture but need significant improvements in both efficiency and long-term stability. Therefore, we have made an attempt to synthesize polyaniline (PANI)–zinc oxide (ZnO) using chemical and emulsion polymerization techniques. The properties of ZnO–PANI films were then systematically characterized with several physical techniques. The electrochemical investigations revealed that the individual redox properties of ZnO and PANI can be maintained in a nanocomposite ZnO–PANI system. Further, results indicated that ZnO–PANI films could exhibit a wide potential window. Moreover, we have observed the formation of a single-layer nano-Schottky junction in the ZnO–PANI film, and interesting positive temperature coefficient properties in ZnO–PANI.

Novel thermal iniferter, synthesized from 1,1,2,2-tetraphenyl-1,2-ethanediol and α-bromoisobutyryl bromide, was used to polymerize styrene and methyl methacrylate through controlled radical polymerization (CRP) mechanism.

The scanning electron microscope images show how the pore diameter is changing as the time of thermal treatment is increasing. In the graphic, one can appreciate the oscillatory behavior of the pore size and the fitting curve obtained when the mathematical model is applied to the experimental data.

Hyperbranched polysiloxanes were synthesized by polyhydrosilylation of silsesquioxane derivatives and vinyl derivatives in the presence of Karstedt's catalyst. The obtained hyperbranched polymers were soluble in common solvents and exhibit good thermal stability. The refractive index values of the obtained polymers tend to decrease with increasing structure size of co-monomers.

The synthesis and photo-polymerization of hyperbranched polyesters containing pendant methacryloyl groups (HBPE-MA) were examined. Polycondensations of 1,4-bis(chloromethyl)benzene (BCMB) with 1,3,5-benzenetricarboxylic acid (BTCA) proceeded very smoothly to give the soluble hyperbranched polyesters (HBPE) in satisfactory high yields using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). Furthermore, HBPE-MA was synthesized by the reaction of HBPE with methacrylic acid (MAA) by the DBU method. The photo-induced radical polymerization of HBPE-MA was performed in the presence of 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-2-one (Irgacure 907) as a photoinitiator in the film state upon UV irradiation to afford the insoluble cured film.

Polypropylene (PP)-knitted fabrics were finished with β-cyclodextrin (β-CD) through their crosslinking with citric acid (CTR). The polyCTR–β-CD polymer-coated fibers were wash resistant. We report that the rate of immobilized CD was controlled by temperature and curing time. The weight increase of the fabrics on their modification with native β-CD and CTR could reach 30 %wt. The treated PP supports were dyed by applying classical dyeing processes involving disperse, acid and reactive dyes. Standard tests of wash fastness (shade change and staining) were conducted and showed that all dyes were fixed, because of inclusion complexation with the immobilized cavities on one hand and sorbed hydrogen or ionic bonds that also occurred between the polyCTR–β-CD coating and the tested dyestuffs on the other.

Isotactic (it-) and syndiotactic (st-) uniform poly(methyl methacrylate)s (PMMAs) with hydroxyl end group, isolated by supercritical fluid chromatography (SFC), were reacted with benzene-1,3,5-tricarbonyl trichloride, and two types of uniform three-arm star-PMMAs with different stereoregular arms, [it/it/st]- and [it/st/st]-3-star-PMMAs, were isolated by SFC from the product mixture. The stereocomplex formation of these stereostar PMMAs was examined in acetone. Although both stereostar PMMAs formed intramolecular stereocomplexes, the [it/st/st]-3-star-PMMA, in particular, was found to form two types of intramolecular stereocomplexes with different hydrodynamic volumes because of different compositions of it- and st-PMMA arms involved in the stereocomplexes.

Hyperbranched polycarbonates (HBPCs) were synthesized by A₂+B₃ polymerization, particularly using di-tert-butyl tricarbonate (DBTC) as A₂ monomer and 1,1,1-tris(4-hydroxyphenyl)ethane (THPE) as B₃ monomer. The terminal functionalized HBPCs with Boc and phenol were obtained by using 1-pot or 2-pot synthesis.

Arm-replaceable star-like nanogels consisting of poly(methyl methacrylate) arms and poly(divinylbenzene) cores with alkoxyamine units at their branching points were synthesized by a combination of atom transfer radical polymerization and nitroxide-mediated radical polymerization. The arms of the star-like nanogels were replaced by means of dynamic covalent exchange processes, and arm detachment and arm exchange reactions were successfully accomplished. The structural changes were confirmed by gel permeation chromatography–multiangle light scattering measurements, small-angle X-ray scattering measurements and scanning force microscopic observation.

Distinct skin-core structured PET X(a) proved notch sensitive as shown in Y(a) when 5–60 μm-deep hairline cracks were introduced. PET was annealed in hot edible oil to alter its morphology and remove internal stresses [PET X(b)] in order to improve toughness. Results showed significant reduction in its notch sensitivity, as shown in Y(b). Therefore, annealing in hot oil proved to be effective in achieving more dispersed skin-core morphology, thus improving the toughness of PET.

Poly(arylene sulfone)s (PASs) containing 9,9′-spirobifluorene (SBF) skeleton in the main chain were synthesized in high yields by the oxidations of the corresponding poly(arylene thioether)s. The PASs exhibited good thermal stability (T_g 257–370 °C, T_d5>400 °C under nitrogen), and showed high solubility in ordinary organic solvents, such as CHCl₃, N-methylpyrrolidone (NMP) and N,N-dimethyl formamide (DMF). All films of PASs showed higher refractive indices in the range 1.65–1.67 at 587.6 nm than those of commercially available polysulfone, whereas it hardly showed birefringence. These excellent optical and thermal properties are derived from the C₂ symmetry and high aromatic component of SBF moiety. Polymer: (i) High refractive index, (ii) Low birefringence, (iii) High thermal stability, (iv) High transparency, (v) High solubility and (vi) Less coloration.

For the purpose of an electric paper application, alginate hydrogel particles were prepared. To increase their zeta potential for well response by electric fields, their surface were modified chemically. Electro-response behaviors were observed between comb-shaped electrodes. It was found that surface-modified alginate hydrogel particles were well responded by applied low voltage 4–9 V.