Kazuki Yamamoto

Polymerization behavior and gel properties of ethane, ethylene and acetylene-bridged polysilsesquioxanes

Soluble bridged polysilsesquioxanes with a range of molecular weight were synthesized from bis(triethoxysilyl)ethane, ethylene, and acetylene (BTES-E1, -E2, and -E3) via hydrolysis and polycondensation reaction by adjusting the water amount. Polymerization behavior of these three trialkoxysilanes was investigated by monitoring the reaction progress by GPC, and 29Si NMR spectrometry of the resulting polymers, poly(BTES-E1), poly(BTES-E2), and poly(BTES-E3), showing that BTES-E1 generated cyclic oligomers at the early stage. In contrast, polymerization of BTES-E2 and BTES-E3 provided no detectable amounts of cyclic oligomers, but afforded linear polymers only. Bulk gels were also prepared by curing the polymers. The gel from poly(BTES-E3) exhibited high thermal stability derived from the rigid acetylene spacer with respect to thermogravimetric analysis. On the other hand, the polymer film of BTES-E1 showed the highest pencil hardness index among the polymers, indicating the tight siloxane network of poly(BTES-E1).

Aggregation-induced emission (AIE) characteristic of water-soluble tetraphenylethene (TPE) bearing four sulfonate salts

Aggregation-induced emission (AIE) characteristic of water-soluble tetraphenylethene (WS-TPE) bearing four sulfonate salts was investigated by the addition of an organic solvent into the WS-TPE aqueous solution. Herein, we demonstrated that WS-TPE can act as a water-soluble AIE compound.

Synthesis and Properties of Polysilsesquioxanes Having Ethoxysulfonyl Group as a Side Chain

Polysilsesquioxane having an ethoxysulfonyl group as a side chain was synthesized to prepare a proton-conductive film composed of a main chain of siloxane. At first, sodium 4-(2-methylallyloxy)benzenesulfonate was chlorinated with thionyl chloride. Next, hydrosilylation with trichlorosilane was carried out in the presence of platinum catalyst followed by treatment with ethanol. Finally, the hydrolytic polycondensation was carried out to provide poly(3-(4-ethoxysulfonylphenoxy)-2-methylpropyl)silsesquioxane. This polysilsesquioxane was heated to form a free-standing film that was brittle and brown in color.

Properties and surface morphologies of organic–inorganic hybrid thin films containing titanium phosphonate clusters

AbstractOrganic–inorganic hybrid thin films containing [Ti4(μ3-O)(OiPr)5(μ-OiPr)3(O3PPh)3]·THF (TiOPPh) were prepared via the hybridization of TiOPPh with poly(vinyl phenol) (PVP), poly(styrene-co-allyl alcohol) (PSA), and poly(bisphenol A-co-epichlorohydrin) (PBE) using spin coating. These thin films were characterized in terms of their transmittance, pencil hardness, and surface morphologies. The transmittance values of the PVP hybrid thin films decreased with the addition of TiOPPh because of the formation of Ti–O–Ph bonds. The pencil hardness values of the hybrid thin films were in the order PVP > PBE > PSA hybrids. Using confocal laser scanning microscopy and atomic force microscopy, the pencil hardness values were determined to be strongly dependent on the surface morphology, such as the roughness and presence of pin holes. The model cluster was synthesized by the reaction of TiOPPh with excess ethanol to study the structures of the TiOPPh in hybrids. From the nuclear magnetic resonance spectroscopy and single-crystal X-ray structure analyses, the main core structure of the model cluster was found to retain the core structure of TiOPPh.Organic–inorganic hybrid thin films containing [Ti4(μ3-O)(OiPr)5(μ-OiPr)3(O3PPh)3]·THF (TiOPPh) as element blocks were prepared via hybridization with the hydroxyl-substituted organic polymers (PVP, PSA, or PBE) by spin-coating. The hybrid thin films were characterized by AFM, DSC, and pencil hardness. The pencil hardness values of the PVP hybrid thin films were in the order 20 > 40 > 0 wt% and were dependent on the surface smoothness. When TiOPPh was reacted with excess ethanol, the core was retained. Therefore, the core of TiOPPh will be retained in the hybrid polymers.

Preparation of Ruthenium Dithiolene Complex/Polysiloxane Films and Their Responses to CO Gas

To develop advanced materials using metal complexes, it is better to prepare metal complexes contained in composite or hybrid films. To achieve this purpose, we synthesized ruthenium complexes with dihalogen-substituted benzendithiolate ligands, [(η6-C6Me6)Ru(S2C6H2X2)] (X = F, 3,6-Cl, Br, 4,5-Cl), 1b–1e. We also investigated preparation of 1c or 1e containing polysiloxane composite films and their reactivity to CO gas. All ruthenium complexes 1b–1e reacted with CO gas, and carbonyl ligand adducts 2b–2e were generated. Ruthenium complexes 1b–1e show two strong absorption peaks around 550 and 420 nm. After exposure to CO gas, these absorption peaks were immediately decreased without a peak shift. A similar trend was observed in 1c or 1e containing polysiloxane composite films. These results indicate that 1c and 1e were easily converted into 2c and 2e, both in the solution and the polysiloxane film during CO gas exposure.

Zinc–diethanolamine complex: synthesis, characterization, and formation mechanism of zinc oxide via thermal decomposition

AbstractZn(OAc)2(H2DEA) was synthesized by the reaction of zinc acetate dihydrate (Zn(OAc)2•2H2O) with diethanolamine (H2DEA), and was characterized using single-crystal X-ray structural analysis, nuclear magnetic resonance spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, and elemental analysis. Zn(OAc)2(H2DEA) had a trigonal bipyramidal geometry comprised of one zinc atom, two acetate groups, and one H2DEA as a neutral tridentate ligand to form two five-membered rings. The states of Zn(OAc)2(H2DEA) heated at various temperatures were determined by FT-IR spectroscopy. At 270 °C, the H2DEA ligand dissociated and was removed. The absorption bands assigned to Zn–O stretching vibration of Zn4O core such as the zinc-oxo cluster appeared. When heated at 500 °C, the absorption bands of μ4-oxozincate and the acetate group disappeared completely and hexagonal wurtzite structural ZnO was formed at 550 °C. A possible thermal decomposition pathway from Zn(OAc)2(H2DEA) to ZnO was proposed. The ZnO film was highly transparent and formed by the deposition of ZnO nanoparticles with size ~40 nm. Zn(OAc)2(H2DEA) was synthesized and characterized. The states of Zn(OAc)2(H2DEA) heated at various temperatures were determined by FT-IR spectroscopy, and the formation mechanism of ZnO was estimated.HighlightsZinc–diethanolamine complex was synthesized by the reaction of zinc acetate with diethanolamine.Zinc–diethanolamine complex was isolated and characterized.The formation mechanism of ZnO was estimated by FT-IR spectra.

Preparation and characterization of stable DQ silicone polymer sols

AbstractStable DQ silicone polymer sols composed of di (D)- and tetra (Q)-functional alkoxysilanes were prepared by the following methods: (i) co-hydrolysis–condensation between diethoxy(dimethyl)silane (DEDMS) and tetraethoxysilane (TEOS) (DEDMS–TEOS as random copolymer sols), (ii) co-hydrolysis–condensation between poly(dimethylsiloxane) (PDMS) and TEOS (PDMS–TEOS as random block copolymer sol), and (iii) triethoxysilylation of a PDMS-lithium salt (PDMS–TES). The polymer sols were characterized by GPC, NMR, and FT-IR. The differences in properties between the structures were analyzed from their thermal stabilities and by using the swelling test. Thermal stabilities of these polymer sols were increased with the increase in the chain length of the D domain and with decrease in hydrolyzability. The swelling of films via polymer sols was decreased with the increase in the degree of crosslinking in sols. DQ silicone polymer sols were prepared by three different methods and characterized by NMR, FT-IR, and GPC. The thermal stabilities of these sols were increased with the increase of the chain-length of D unit and hydrolysis resistance. Also, the solvent uptake was increased with the decrease of the degree of crosslinking in solsHighlightsDQ silicone sols with different content and length of D units were prepared by using two methods.Triethoxysiloxyl-terminated PDMS of higher molecular weight was prepared.The structures of these polymer sols were characterized by 29Si NMR spectra.The differences in properties of the structures were evaluated from their thermal stabilities and by using the swelling test.