silsesquioxane

The rheological properties of entangled polymers loaded with very small, strongly attractive polyhedral oligomeric silsesquioxane (POSS) fillers differ from that of nanocomposites with larger fillers by (1) the shorter breadth of the entanglement plateau and (2) the relatively unchanged terminal viscosity with increasing POSS loading. Although such anomalous rheological properties can rewrite the property-processing map of materials (e.g., high glass transition temperature and low viscosity), their mechanism remains unclear...

Realistically, green manufacturing of transparent superhydrophobic surfaces (SHSs) and high liquid impalement resistance for outdoor engineering are very necessary but pretty challenging. To address this, an almost all-waterborne system composed of synthesized partially open-cage fluorinated polyhedral oligomeric silsesquioxane bearing a pair of -OH (poc-FPOSS-2OH), silica sol, and resin precursor is engineered. The transparent SHSs facilely formed by this system are featured with the exclusive presence of wrapped silica nanoparticle (SiNP) dendritic networks at solid-gas interfaces...

Starch is one of the most frequently preferred natural polymers in hydrogel synthesis. Herein, we combined two strategies of associating brittle and ductile networks in a structure and incorporating inorganic particles into the polymeric gel to design mechanically enhanced nanocomposite double network (DN) starch gels. For the first time in the literature, nanocomposite starch gels (s-NC) were designed by cross-linking starch chains with 8-armed glycidyl-polyhedral oligomeric silsesquioxane (g-POSS) units. Fourier Transform Infrared Spectroscopy and Energy Dispersive X-Ray Spectroscopy analyses have proven that g-POSS is included in the gel structure and is homogeneously distributed throughout the network...

A series of fibrous meshes based on liquid crystalline polyurethane/POSS composites were prepared. Two types of polyhedral oligomeric silsesquioxanes (POSSs) of different structures were chosen to show their influence on electrospun fibers: aromatic-substituted Trisilanolphenyl POSS (TSP-POSS) and isobutyl-substituted Trisilanolisobutyl POSS (TSI-POSS) in amounts of 2 and 6 wt%. The process parameters were selected so that the obtained materials showed the highest possible fiber integrity. Moreover, 20 wt% solutions of LCPU/POSS composites in hexafluoroisopropanol (HFIP) were found to give the best processability...

Silsesquioxane dendrimers offer versatile structural potential, prompting our innovative synthesis of G1 and G2 polyol dendritic systems with diverse silsesquioxane cores, ranging from mono-T8 to difunctional and tetrafunctional double-decker silsesquioxanes. Through a strategic combination of hydrosilylation and O -silylation reactions, we have formed an extensive compound library. A major focus was directed toward investigating the reaction conditions of G1.5 dendrimers, as well as evaluating the stability and reactivity of the novel -O-Me2 Si-H group...

While smaller polyhedral oligomeric silsesquioxanes TnRn (POSS) are readily accessible or even commercially available, unambiguously authenticated larger systems (n > 12) have barely been reported. Synthesis and isolation procedures are lengthy, and yields are often very low. Herein, we present the surprisingly straightforward and high-yielding access to the phenyl-substituted derivative of a so far only postulated second D3h-symmetric T14 isomer and with that the largest crystallographically characterized POSS cage with organic substituents...

The silsesquioxane ligand ( i Bu)7 Si7 O9 (OH)3 ( iBu POSSH3 ) is revealed as an attractive system for the assembly of robust polynuclear complexes of uranium(III) and allowed the isolation of the first example of a trinuclear U(III) complex ([U3 ( iBu POSS)3 ]) that exhibits magnetic communication and promotes dinitrogen reduction in the presence of reducing agent.

The glass transition in polyurethanes is a complicated phenomenon governed by a multitude of factors, including the microphase separation, which in turn depends strongly on the molar mass of the hard and soft segments, as well as the presence of additives. In this work, we study the effects of the segments' length on the microphase separation and consequently on the calorimetric and dynamic glass transition of a polyurethane with aliphatic, "flexible" hard segments. It is found that the dependence of the calorimetric glass transition follows the same principles as those in systems with aromatic hard segments...

Organic-silica hybrid monolithic materials have attracted considerable attention as potential stationary phases in separation science. These materials combine the advantages of organic polymer and silica-based monoliths, including easy preparation, lower back pressure, high permeability, excellent mechanical strength, thermal stability, and tunable surface chemistry with high surface area and selectivity. The outstanding chromatographic efficiency as stationary phase of hybrid monolithic capillary columns for capillary liquid chromatography and capillary electrochromatography has been reported in many papers...

Novel hybrid silsesquioxane-based liquid crystalline derivatives with varied lengths of spacers and tails have been synthesized by hydrosilylation reactions of octakis(dimethylsiloxy)silsesquioxane and side-on mesogens via a platinum catalyst. The thermal behavior of three types of silsesquioxane-based liquid crystals (LCs), differentiated by the molecular structure of mesogens, was investigated by differential scanning calorimetry (DSC) and polarising optical microscopy (POM). Temperature-dependent small and wide-angle X-ray scattering was used to verify liquid crystalline phases, revealing that the silsesquioxane-based derivatives formed hexagonal columnar and nematic mesophases, and the effect of the molecular structure of the mesogens and the spacer length on the formation of LC phases is discussed...

Biomass is one of the powerful alternatives to petroleum-based packaging materials. Herein, carboxymethyl hemicellulose (CMH) based films (CPF) were prepared using a convenient strategy. The chains of CMH provided the necessary supporting matrix, and the aminopropyl polyhedral oligomeric silsesquioxane (POSS-NH2 ) regulated the thermal and barrier properties of the CPF. The secondary amide groups and hydrogen bond were appeared in chemical structure, and SEM-EDS results indicated the preferable dispersion and compatibility of POSS-NH2 in CPFs...

Two-dimensional (2D) materials such as MXenes have shown great potential for energy storage applications due to their high surface area and high conductivity. However, their practical implementation is limited by their tendency to restack, similar to other 2D materials, leading to a decreased long-term performance. Here, we present a novel approach to addressing this issue by combining MXene (Ti3 C2 T x ) nanosheets with branched ionic nanoparticles from polyhedral oligomeric silsesquioxanes (POSS) using an amphiphilicity-driven assembly for the formation of composite monolayers of nanoparticle-decorated MXene nanosheets at the air-water interface...

The bicyclic silicon(I) ring compound Si4{N(SiMe3)Mes}42 was used as starting material in reactions with chalcogens and chalcogen transfer agents at low temperatures. This results in the selective formation of new cage compounds. With Me3NO a silicon oxide with adamantane-type cage 3 was isolated that represents the first isolated T4 silsesquioxane. The reactions propylenesulfide and red selenium gave direct access to defect heterocubane-type cages 4 and 5 with three Si-Si bonds wherein the silicon atoms adopt different low oxidation states of +I and +III...

Cellulose/poly (glycerol citrate) reinforced with thiol-rich polyhedral oligomeric silsesquioxane and apple peel (POSS-SH@CAG-CEL/AP) was synthesized using gelation method in the presence of glutaraldehyde as a crosslinker agent and used as an efficient composite hydrogel for elimination of Tl(Ι) from aqueous solutions. This composite hydrogel and synthesized thiol-rich polyhedral oligomeric silsesquioxane were characterized by elemental analysis, FT-IR, NMR, TGA, and FE-SEM techniques. The effects of synthetic and environmental parameters on the adsorption capacity of the composite hydrogel were investigated and it was found that thiol-rich polyhedral oligomeric silsesquioxane has improved the hydrogel properties including the Tl(Ι) uptake and the thermal stability...

Aberration-corrected electron-beam lithography (AC-EBL) using ultra-thin electron transparent membranes has achieved single-digit nanometer resolution in two widely used electron-beam resists: poly (methyl methacrylate) (PMMA) and hydrogen silsesquioxane (HSQ). On the other hand, AC-EBL implementation on thick, electron-opaque substrates is appealing for conventional top-down fabrication of quantum devices with nanometer-scale features. To investigate the performance of AC-EBL on thick substrates, we measured the lithographic point spread function (L-PSF) of a 200 keV aberration-corrected scanning transmission electron microscope (AC-STEM) by defining both positive and negative patterns in PMMA thin films, spin-cast on thick SiO2 /Si substrates...

Crystalline silicon particles sustaining Mie resonances are readily obtained from the thermal processing of hydrogen silsesquioxane (HSQ). Here, the mechanisms involved in silicon particle formation and growth from HSQ are investigated through real-time in situ analysis using an environmental transmission electron microscope and X-ray diffractometer. The nucleation of Si nanodomains is observed starting around 1000 °C. For the first time, a highly mobile intermediate phase is experimentally observed, thus demonstrating a previously unknown growth mechanism...

Methacrylate-based polyhedral oligomeric silsesquioxane (POSS) is one of the new composites used as a dental resin. Both monofunctional methacryl isobutyl POSS (MIPOSS) and multifunctional methacryl POSS (MAPOSS) are reported to be possible resins that possess the desired properties for using them as dental resins. Our group's previous comparative study on these two resins showed that the MAPOSS composite has superior mechanical properties compared with the MIPOSS composite. In this article, molecular dynamic simulations (MD simulations) are performed to study the water sorption in these two composites...

Ladder-like poly(methacryloxypropyl)-silsesquioxanes (LPMASQ) are photocurable Si-based gels characterized by a double-stranded structure that ensures superior thermal stability and mechanical properties than common organic polymers. In this work, these attractive features were exploited to produce, in combination with alumina nanoparticles (NPs), both unmodified and functionalized with methacryloxypropyl-trimethoxysilane (MPTMS), LPMASQ/Al2 O3 composites displaying remarkable thermal conductivity. Additionally, we combined LPMASQ with polybutadiene (PB) to produce hybrid nanocomposites with the addition of functionalized Al2 O3 NPs...

The distinctive cage-like structure of polyhedral oligomeric silsesquioxane (POSS) materials makes them highly effective fillers in composite membranes for separation applications. However, realizing their full potential in the application often requires specific surface functionalization with various groups. However, this requirement remains challenging owing to the limitations of wet-chemistry approaches, which frequently result in the generation of hazardous chemical by-products. In this paper, a "green" stirring plasma strategy is presented for the functionalization of octa-methyl POSS sub-micron particles into designable oxygen-containing functional groups using a low-pressure oxygen plasma from combined continuous wave and pulsed (CW+P) modes...

Circularly polarized luminescence (CPL) is typically achieved with a chiral luminophore. However, using a helical nanosized fused quartz cell consisting of chiral silica, we could control the wavelength and helical sense of the CPL of an achiral luminophore. Chiral silica with a helical nanostructure was prepared by calcining a mixture of polyhedral oligomeric silsesquioxane (POSS)-functionalized isotactic poly(methacrylate) ( it -PMAPOSS) and a small amount of chiral dopant. The chiral silica encapsulated functional molecules, including luminophores, along the helical nanocavity, leading to induced circular dichroism (ICD) and induced circularly polarized luminescence (iCPL)...