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Sulfonated free-standing films were prepared by sulfonation of the free-standing films of 3-mercaptopropyl(trimethoxy)silane (MTMS)/1,2-bis(triethoxysilyl)ethane (BTESE) copolymers. The sulfonyl group content was 1.23 mmol g⁻¹ when the composition of MTMS/BTESE was 1:2, which sulfonyl group content at 150 °C was 1.20 mmol g⁻¹.

Platinum nanoparticles stabilized by linear polyethyleneimine (LPEI) were prepared by the liquid-phase reduction of chloroplatinic(IV) acid with sodium borohydride. The averaged radii of particles were 3.26 and 1.76 nm when the molecular weights of LPEI were 25 000 and 2150, respectively. These nanoparticles were well dispersed in water in the range of pH 1–6. Branched polyethyleneimine also provided nanoparticles that dispersed in water in the range of pH 0–8. Linear poly(ethyleneimine-co-N-methylethyleneimine) gave nanoparticles that dispersed in water in the range of pH −1 to 15.

Novel nickel–molybdenum–platinum ternary alloy nanoparticles (NiMoPtNPs) stabilized by oleylamine were prepared by a hot-soap method. The following ligand-exchange reaction of oleylamine with 50% N-methylated linear poly(ethyleneimine-co-N-methylethyleneimine) (poly(EI-co-NMEI)) provided poly(EI-co-NMEI)-protected NiMoPtNPs. The average radii of poly(EI-co-NMEI)-protected NiMoPtNPs were 1.9–2.5 nm and were decreased as compared with oleylamine-protected NiMoPtNPs. Poly(EI-co-NMEI)-protected NiMoPtNPs were dispersed in methanol, ethanol and water in the range of pH −1 to 14. The energy-dispersive X-ray spectrometric analysis showed that poly(EI-co-NMEI)-protected NiMoPtNPs are a ternary metal alloy.

The transparent and flexible photocatalytic films composed of titanium oxide, organophosphonate-modified polysilsesquioxane, and poly(bisphenol A-co-epichlorohydrin) were prepared. The effects of hydroxy group ratio and organic substituent on phosphorus atoms in these films were evaluated by appearance and photocatalytic ability. Film using anchoring layer with APPS-low was formed large cracks, while films with other anchoring layers were formed no cracks. However, all films were formed small cracks after a 10-day durability test. All films showed photodegradation ability of methylene blue, photoinduced hydrophilicity, and photocatalytic bactericidal effects on Escherichia coli.

In this work, POSS with an acetylacetonato group (POSS-acac) and metal–coordination polymers comprising POSS-acac (CP(Metal)s) were synthesized. The possible structure of CP(Metal)s was estimated from the UV–Vis spectrum and the residual mass after burning off and the surface morphologies of the CP(Metal)s were observed using scanning electron microscopy.

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.

We synthesized poly(bisphenol A-co-ephichlorohydrin)–titanium phosphonate clusters (Ti₄P₃: [Ti₄(μ₃-O)(OiPr)₅(μ-OiPr)₃(O₃PPh)₃]·thf; Ti₄P₄: [Ti(OiPr)(acac)(O₃PPh)]₄; Ti₇P₆: Ti₇(μ₃-O)₂ (OiPr)₆(μ-OiPr)₆(O₃PBnBr)₆). From the result of swelling test using tetrahydrofuran, Ti₇P₆ cluster showed highest cross-linking efficiency.

Bridged polysilsesquioxanes are promising materials for reverse osmosis membranes because they exhibit robust properties. To investigate the effects of the polarity and rigidity of organic components of the polymer on the water permeability of the membrane, two alkoxysilane monomers, 2,5-bis[2-(triethoxysilyl)vinyl]pyridine (BTES-VP) and 1,4-bis[2-(triethoxysilyl)vinyl]benzene (BTES-VB), were synthesized. Both membranes prepared from BTES-VP and BTES-VB rejected 95–97% of aqueous sodium chloride and displayed water permeances of 1.1 × 10⁻¹³ and 8.5 × 10⁻¹⁴ m³/(m²· Pa· s), respectively.

Titanium phosphonate (TiOPPh: [Ti₄(μ₃-O)(OⁱPr)₅(μ-OⁱPr)₃(PhPO₃)₃]·thf) was synthesized. TiOPPh was mixed with poly(methyl methacrylate) (PMMA) or poly(vinyl alcohol) (PVA) to prepare organic–inorganic hybrid polymer films. The film using PMMA was formed by the interaction between organic and inorganic components. The temperatures of 10% weight loss of TiOPPh–PMMA were 30 °C higher than that of PMMA only. The film using PVA was formed by the alcohol exchange reaction between TiOPPh and PVA. The transparency of TiOPPh-PVA in the visible region was higher than that of PVA only.

A polysilsesquioxane-based organic-inorganic hybrid membrane was prepared and applied as a proton-conducting membrane for fuel cells. A membrane of a random copolymer of ethyl 4-(2-methyl-3-triethoxysilylpropoxy)benzenesulfonate and triethoxy(methyl)silane showed proton conductivity of 2.0 × 10⁻⁵ to 1.1 × 10⁻³ S cm⁻¹ at room temperature. A membrane of a block copolymer of poly(3-(4-ethoxysulfonylphenoxy)-2-methylpropyl)silsesquioxane (SPES) and polymethylsilsesquioxane showed proton conductivity of 2.5 × 10⁻³ S cm⁻¹. The mixture of SPES and poly(vinyl alcohol), poly(ethylene oxide), or polyoctahedralpolysilsesquioxane showed proton conductivity of 2.7 × 10⁻³, 1.5x10⁻³ or 2.5 × 10⁻³ S cm⁻¹, respectively. The open-circuit voltage of the SPES membrane was 0.92 V.

Organic–inorganic hybrids containing [Ti₄(μ₃-O)(OiPr)₅(μ-OiPr)₃(O₃PPh)₃]·thf (TiOPPh) as element-blocks were prepared by hybridization with silicone polymers (poly(dimethylsiloxane) (PDMS), poly(methylsilsesquioxane) (PMS) or poly(ethoxysilsesquioxane) (PEOS)), the hydroxyl groups substituted organic polymers (poly(vinyl alcohol) (PVA), poly(4-vinylphenol), poly(styrene-co-allyl alcohol) or poly(bisphenol A-co-epichlorohydrin) (PBE)) or poly(methyl methacrylate) (PMMA). The concentration of TiOPPh was increased to 40 wt% to form free-standing hybrid films with PDMS, PMS, PVA and PBE polymers. The tensile strengths and elongations of PMMA and PVA films were higher improved than only polymers because TiOPPh acted good crosslinkers.

Reverse osmosis (RO) membranes composed of polyamides and cellulose acetates are used as separation layers in pure-water production. However, improving the separation performance and antifouling properties of RO membranes is necessary. This focus review described the composite reverse osmosis membranes with optimal amounts of polyhedral oligomeric silsesquioxanes (POSS), which are cage-shaped, subnanosized molecules exhibiting organic–inorganic hybrid structures, showed improved water flux, NaCl rejection, antichlorine and antifouling properties, and mechanical strength.

Water desalination through a reverse osmosis (RO) membrane is an important technology for producing pure water from seawater. High-performance membrane materials have been extensively developed because these materials are useful as core elements in practical water separation processes. Bridged polysilsesquioxane (PSQ)-derived membranes are promising candidates for robust RO membranes because they exhibit high thermal stability and chlorine resistance compared to conventional aromatic polyamide membranes. This review reports on our recent studies involving the development of RO membranes based on bridged PSQs.