Kozo Matsumoto

Synthesis and characterization of novel functional electrosterically stabilized colloidal particles prepared by emulsion polymerization using a strongly ionized amphiphilic diblock copolymer.

Amphiphilic diblock copolymers such as poly(styrene)-block-poly(styrene sulfonate) (PS-b-PSS) (Matsuoka, H.; Maeda, S.; Kaewsaiha, P.; Matsumoto, K. Langmuir 2004, 20, 7412), belong to a class of new polymeric surfactants that ionize strongly in aqueous media. We investigated their self-assembly behavior in aqueous solutions and used them as an emulsifier to prepare electrosterically stabilized colloidal particles of different diameters between 70 to 400 nm. We determined the size, size polydispersity, effective charge, total dissociable charge, structural ordering, and phase behavior using light scattering, transmission electron microscopy (TEM), small-angle neutron scattering (SANS), and potentiometric titration. These experiments clearly demonstrated that all of the synthesized particles were nearly monodisperse (polydispersity index<or=6%). The results of DLS and TEM clearly suggested the existence of hairy particles. The form factors obtained by SANS were well described by a polydisperse sphere model. The estimated total number of dissociable charges per particle was found to be larger than 10(4)e, whereas the effective charges per particle were found to be around 1000e. This significant difference suggested the confinement of charges inside the corona regions of the polyelectrolyte brush shell. Finally, these monodisperse particles were found to self-assemble into 3D ordered colloidal crystalline arrays at a low volume fraction (=0.00074) that diffract light in the visible region.

Synthesis and properties of novel poly(hydroxyurethane) from difunctional alicyclic carbonate and m-xylylenediamine and its possibility as gas barrier materials

Poly(hydroxyurethane) was synthesized by polyaddition of difunctional alicyclic carbonate (DCHC) and m-xylylenediamine (mXDA), and its oxygen transmittance rate was examined. DCHC was prepared from industrially available difunctional alicyclic epoxide, 3′,4′-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate (CEL2021P), by insertion of carbon dioxide using N-methyltetrahydroprimidine as a promoter and tetrabutylammonium bromide as a catalyst. Poly(hydroxyurethane), poly(DCHC-mXDA) (Mnxa0=xa02600, Mwxa0=xa05700 GPC relative to polystyrene standards), was obtained by heating DCHC and mXDA in N,N-dimethylacetamide at 100xa0°C. The obtained polymer was thermally stable up to 220xa0°C, and exhibited good processability in film preparation. The oxygen transmission rate of the polymer was found to be 127xa0cm3/m2xa0dayxa0atm at 5xa0μm film thickness laminated with polypropylene films, indicating its relatively high gas barrier property.Graphical abstractPolyhydroxyurethane was synthesized by polyaddition of difunctional alicyclic carbonate (DCHC) and m-xylylenediamine (mXDA) and its oxygen transmission rate was examined. We found that the polymer possess high gas barrier property.

Construction of reversible crosslinking–decrosslinking system consisting of a polymer bearing vicinal tricarbonyl structure and poly(ethylene glycol)

In this article, we report a novel reversible crosslinking–decrosslinking system consisting of a polymer bearing vicinal tricarbonyl moieties in its side chains and poly(ethylene glycol) (PEG). A mixture of the tricarbonyl polymer and PEG (0.1 equiv of OH groups relative to the vicinal tricarbonyl moieties) in CH2Cl2 spontaneously turned into an orange-colored gel, in which a network structure was formed through hemiketal linkages. Conversely, the resulting networked polymer could be decrosslinked by treatment with water-containing solvent to recover the linear vicinal tricarbonyl polymer as its hydrate in 90xa0% yield. Following dehydration process by heating at 100xa0°C under reduced pressure regenerated the original vicinal tricarbonyl polymer.

Synthesis of thiourethanes and poly(thiourethane)s bearing carboxylic groups by nucleophilic acylation using cyclic acid anhydrides

A mercapto group generated by addition of 5-phenoxymethyl-1,3-oxathiolane-2-thione and benzylamine could react with cyclic acid anhydrides to give the corresponding carboxylic acids. This method was applied to a polymer modification. Poly(thiourethane)s containing mercapto groups were prepared from difunctional five-membered cyclic dithiocarbonates and diamines could react with succinic or glutaric anhydride to give the corresponding poly(thiourethane)s bearing carboxyl group in the side chains in high yield. Thermal properties of the obtained polymers were examined by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The obtained polymers showed 5xa0% weight loss temperatures (Td5) at 170 and 216xa0°C. These polymers exhibited glass transition temperatures (Tg) at 52 and 57xa0°C, respectively. Furthermore, a cross-linked poly(thiourethane) was readily obtained using difunctional cyclic acid anhydride, 1,2,3,4-butanetetracarboxylic dianhydride as a cross linker.

Synthesis and characteristics of networked polycarbosilanes having urethane-crosslinked glucose groups

AbstractNetworked polycarbosilanes having glucose groups were synthesized and their physicochemical properties were investigated. Film-shaped polysilacyclobutane having glucose pendant groups was crosslinked by thermal urethane formation with a crosslinker, hexamethylene diisocyanate (HMDI). Several films were prepared by varying the feed ratio of [Glucose]/[HMDI]. Thermal stability, phase transitions, mechanical strength, and water absorption were examined by thermal gravimetric analysis, differential scanning calorimetry, tensile tests, and immersion swelling in water. We found that the networked polycarbosilanes having glucose groups were thermally stable, flexible, and tough materials with moderate hydrophilicity, which depends on the urethane crosslinking density.Graphical abstractNetworked polycarbosilanes having glucose groups were synthesized and their physical properties were investigated. Film-shaped polysilacyclobutane having glucose pendant groups was crosslinked through urethane formation by heating with a cross-linker, hexamethylene diisocyanate. We found that they were thermally stable, flexible, and tough materials with moderate hydrophilicity.n

Syntheses and thermal properties of polyesters bearing a carbosilane repeating unit

New polyesters bearing a carbosilane repeating unit (–C–Si(CH3)2–C–), 1a and 1b, and reference polyesters with the corresponding carbon-based units 2a and 2b were synthesized and evaluated to study the effect of the carbosilane segment on their thermal properties. DSC analysis revealed that 1a and 1b exhibited glass transition temperatures (Tg) of −72.6 and 11.6xa0°C, respectively, which were lower than those of 2a and 2b (–53.2xa0°C for 2a and 63.6xa0°C for 2b), indicating that the substitution of carbon atoms on polyester backbone with silicone atoms is effective method to change the Tg of polyesters. Furthermore, 1a and 1b showed good thermal stability (Td5xa0=xa0304xa0°C for 1a and 309xa0°C for 2a). These results indicate that carbosilane segment may be a promising soft segment for developing new polyester-based materials.

Synthesis and characterization of polyurethanes bearing carbosilane segments

Novel polyurethanes bearing carbosilane segments (1a–c) were synthesized. Their thermal and mechanical properties were compared with corresponding reference polyurethanes bearing carbon-based backbone (2a–c). The thermal properties of these polyurethanes were investigated by DSC and TGA. Glass transition temperature was significantly reduced by substituting carbon atom with silicon (1a–c). Moreover, the thermal decomposition temperature of 1a–c was found to be comparable to 2a–c. Furthermore, Youngs moduli of 1a–c were lower than those of 2a–c. A large potential of carbosilane unit as a soft segment for building new polyurethanes have been demonstrated in this paper.

Nanostructure of Polymer Monolayer by X-Ray and Neutron Reflectometry

測定は,嵩分子界面化学の基礎研究において必須の界面ナノ構造情報を与えてくれる。これにより,イオン性両親媒性高分子水面単分子膜や高分子電解質ブラシのナノ構造と,その鎖長,鎖長比,表面圧依存性など詳細を調査したところ,絨毯(じゅうたん)層の存在や塩濃度依存性など,その意外な特性が明らかとなった。毛利恵美子