Preparation and Characterization of Amino-Functionalized Zeolite/SiO2 Materials for Trypsin–Chymotrypsin Co-immobilization

Catalysis Letters - Inorganic supports have attracted increased attention in enzyme immobilization since they not only improve enzyme stability but also reduce the final cost of enzymatic...     

Preparation,Characterization, and Properties of Novel Polyimide–SiO2 Hybrid Composites Based on Bipyridine for Low Dielectric Applications

Novel low dielectric polyimide–SiO₂ hybrid materials containing bipyridine were prepared with three-step sol–gel process from poly(amic acid)s. (3-Aminopropyl)triethoxysilane as coupling agent was used to increase the intrachain chemical bonding between the polyimide and SiO₂ groups. The thermal, dielectric, and physical properties of the hybrid materials were investigated and correlated with the porous structure. The glass transition temperatures of all the hybrids were found to be higher than polyimides. The effect of SiO₂ groups on the porous structure and dielectric properties was investigated. The dielectric constant of the hybrid materials was observed a decrease from 3.30 to 2.15 with increased SiO₂ amount.     

Heat-Insulating Properties of High-Alumina Materials Filament-Reinforced with Glass Fiber of the Al2O3–SiO2 and Al2O3–SiO2–ZrO2 Systems

Refractories and Industrial Ceramics - Refractory heat-insulating materials produced in Russia are characterized. The thermal stability of high-alumina heat-insulating materials filament-reinforced...     

Sol-Gel Preparation and Properties of Thin-Film Biomaterials for the SiO2–P2O5–CaO–ZnO System

Glass and Ceramics - Thin films for the SiO2–P2O5–CaO–ZnO system were synthesized by the sol-gel method. The compositions and technology for producing thin-film materials on a...     

Study on the Preparation and Characterization of Biodegradable Polylactide/SiO2–TiO2 Hybrids

In this study, the silicic acid produced from sodium metasilicate hydrate and titanium tetraisopropylate were chosen as the ceramic precursors for the modification of biodegradable polylactide (PLA) through an in situ sol-gel process and the melt blending method. In addition, acrylic acid grafted polylactide (PLA-g-AA) was studied as an alternative to PLA. Hybrids were characterized by Fourier transform infrared spectroscopy, ²⁹ Kumar , P. ; Badrinarayanan , M.S. ; Sastry , M. Nanocrystalline TiO₂ studied by optical, FTIR and X-ray photoelectron spectroscopy: correlation to presence of surface states . Thin Solid Films 2000 , 358 , 122 – 130 .[Crossref], [Web of Science ®] , [Google Scholar]Si solid-state nuclear magnetic resonance (NMR), thermogravimetry analysis (TGA), scanning electron microscope (SEM), and Instron mechanical tester. The result was that properties of the PLA-g-AA/SiO₂–TiO₂ hybrid were superior to those of the PLA/SiO₂–TiO₂ hybrid. This was because the carboxylic acid groups of acrylic acid acted as coordination sites for the silica-titania phase to allow the formation of stronger chemical bonds. The ²⁹ Kumar , P. ; Badrinarayanan , M.S. ; Sastry , M. Nanocrystalline TiO₂ studied by optical, FTIR and X-ray photoelectron spectroscopy: correlation to presence of surface states . Thin Solid Films 2000 , 358 , 122 – 130 .[Crossref], [Web of Science ®] , [Google Scholar]Si solid-state NMR showed that Si atoms coordinated around SiO₄ units were predominantly Q₃ and Q₄. The 10 wt.% SiO₂–TiO₂ content gave the maximum values of tensile strength and glass transition temperature in PLA/SiO₂–TiO₂ and PLA-g-AA/SiO₂–TiO₂ both because excess SiO₂–TiO₂ particles caused separation between the organic and inorganic phases.     

The Preparation of Core–Shell P(St-MMA)–SiO2 Hybrid Nanoparticles and Filling in the Styrene/n-butyl Acrylate Adhesive

In this study, core–shell poly(styrene-methyl methacrylate) (P(St-MMA))–SiO₂ hybrid nanoparticles were prepared successfully by emulsion polymerization. Firstly, nanosilica particles were modified by oleic acid (OA) in order to introduce the polymerization active vinyl groups and hydrophobic groups onto the nanosilica. This was followed by graft copolymerization onto the modified nanosilica particles to obtain P(St-MMA)–SiO₂ hybrid nanoparticles. The hybrid nanoparticles were characterized by: transmission electron microscope (TEM); Fourier transform infrared spectroscopy (FT-IR); dynamic light scattering (DLS); and thermal gravimetric analysis (TGA). The results indicate that the hybrid particles had a regular spherical morphology with a diameter ranging from 50 to 80 nm. A reasonable mechanism for the preparation of the core–shell hybrid nanocomposites was presented. The obtained hybrid nanoparticles were subsequently (incorporated into) filled in the poly(styrene-n-butyl acrylate) (PSBA) latex. The effect of (hybrid nanoparticle concentration) filling content on the physicochemical properties of PSBA latex and the resulting node strength per monofilanment of the fibre glass gridding cloth was investigated. The results indicated that the node strength/monofilanment of the fibre glass gridding cloth coated with the PBSA latex filled with 1.0 wt% hybrid nanoparticles demonstrated greatest improvement among all the investigated PSBA latex. This result is related to the rheological properties of the latex. Moreover, the water-resistance property of PSBA composite film was found to be enhanced when compared with that of unfilled PSBA film.     

Erratum to: Preparation of Mullite–TiC–ZrC-Ceramic Materials by a Plasma-ARC Method and Their Properties

Refractories and Industrial Ceramics -     

Erratum to: Preparation of Mullite–TiC–ZrC-Ceramic Materials by a Plasma-ARC Method and Their Properties

Refractories and Industrial Ceramics -     

Correction to: Preparation and Characterization of Amino‑Functionalized Zeolite/SiO2 Materials for Trypsin–Chymotrypsin Co‑immobilization

Catalysis Letters - A correction to this paper has been published: https://doi.org/10.1007/s10562-021-03665-x     

Physical and Mechanical Properties of Hot-Pressed Materials of the ZrB2–TaC–SiC System

Refractories and Industrial Ceramics - High-density (with a relative density of up to 98.8%) ultra-high-temperature ceramic materials (UHTCs) based on the ZrB2–TaC–SiC system were...     

The Preparation of Metal–Organic-Framework/Boron Phosphate Hybrid Materials for Improved Performances in Proton Exchange Membranes

New types of metal–organic framework based hybrid materials are designed and prepared, which involving the hybridization of various content of boron phosphate (BPO₄) with the precursor of HKUST-1. The structure of obtained HKUST-1/BPO₄ hybrid materials (HB) is fully investigated, and then applied to construct sulfonated poly (ether ether ketone) (SPEEK) based proton exchange membranes (SPEEK/HB). Owing to effective interactions between hybrid materials and SPEEK matrix, the achieved composite membranes reflect a considerable improvement in mechanical and thermal stability, oxidative stability, methanol permeation, and proton conductivity. In particular, the tensile strength of SPEEK/HB-20 composite membrane is 41.3 MPa, which is 1.5 times higher than pristine SPEEK, and the methanol permeability reduced to one-third of SPEEK at the same time. The SPEEK/HB-10 displays the highest proton conductivity of 37.4 mS cm⁻¹ at 80 °C, which is obviously higher than pristine SPEEK. These results reveal that the hybridization of HKUST-1 with BPO₄ provide a promising candidate in the modification of proton exchange membranes (PEMs), and this strategy also possess great application potential in other types of MOFs-based hybrid materials.     

Synthesis and Properties of Mullite–Sialon–ZrB2Materials Produced Using a Spark-Plasma Technique

Refractories and Industrial Ceramics - The sialon-to-ZrB2 ratio during spark-plasma sintering at pressing load 75 MPa and 1200 – 1600°C influenced the phase composition, Si3N4 and Al2O3...     

Preparation and Properties of Upconversion Luminescent Materials of Y202S：Yb,Ho

利用硫熔法制备了不同浓度的 Yb 和 Ho 掺杂的 Y2O2S：Yb,Ho 上转换发光材料。采用 X 线衍射仪、扫描电镜和荧光光谱仪对粉体的相组成、形貌和上转换发光性能进行表征。结果表明：不同浓度的 Yb 和 Ho 掺杂后没有改变 Y2O2S 的晶体结构;颗粒形貌较为规则,多呈现多面体状,分散性较好,颗粒表面很光滑;在 980nm 激光激发下,Y2O2S：Yb,Ho 呈现出以绿光发射为主的上转换荧光,Yb 的最佳掺杂量为 8% （摩尔分数）,Ho 的最佳掺杂量为 2% （摩尔分数）,Ho3＋和 Yb3＋掺杂浓度可显著影响不同颜色发射峰的强度;对激活离子 Ho3＋来说,同类离子之间发生能量传递和交叉弛豫行为,导致上转换荧光强度发生猝灭;对敏化离子 Yb3＋来说,Yb3＋吸收能量,以热的形式释放出来,产生杂质猝灭。     

Preparation and characterization of equimolar SiO2–Al2O3–TiO2 ternary aerogel beads

Crack-free mesoporous equimolar SiO₂–Al₂O₃–TiO₂ ternary aerogel beads have been synthesized and characterized. Silica sol, alumina sol, and titania sol were synthesized individually to prevent the formation of inhomogeneous structure due to the different hydrolization and polymerization rate of individual precursor. After mixing these three types of acidic sols, SiO₂–Al₂O₃–TiO₂ ternary beads were prepared by the ball dropping method. The ternary aerogel beads were typically mesoporous, showing high surface area (305 m² g^?1), large pore volume (1.32 cm³ g^?1), and high surface acid amount (0.884 mmol NH₃ g^?1). Moreover, the acid sites of the ternary aerogel beads showed higher thermal stability than those of binary aerogel beads. Gradient drying (GD), supercritical drying (SD), ambient drying (AD), extended aging (EA) and hydrophobic modifying drying (HM) have been employed to investigate the effects of drying method on the characteristics of the aerogel beads. The surface areas of the ternary aerogel beads obtained by different drying methods decrease in the sequence EA > HM > GD > SD > AD. The ternary aerogel beads have been characterized by scanning electron microscopy, nitrogen adsorption, X-ray powder diffraction, Fourier-transform infrared spectroscopy (FTIR), solid-state NMR, temperature-programmed desorption measurements, pyridine adsorption FTIR, and differential scanning calorimetry.     

Preparation and Properties of Novel Quaternized Metal–Polymer Matrix Nanocomposites

A new class of PANI/Sn(II)SiO₃/FCNTs nanocomposite was synthesized by mixing polyaniline into the gel of Sn(II)SiO₃ followed by FCNTs (Polyaniline/Sn(II)SiO₃/Functionalized Carbon nanotubes). The physico-chemical characterization was carried out by scanning electron microscope, XRD (X-ray Diffraction), FTIR (Fourier Transform Infrared Spectroscopy), ultraviolet–visible spectroscopy, and simultaneous thermogravimetric analysis studies. The ion-exchange capacity (1.2 meq/g) and distribution studies were also determined to understand the ion-exchange capabilities. The DC electrical conductivity studies revile it in the range of 3–5 × 10^?3 S/cm. On the basis of distribution studies, ion-selective membrane electrode was designed for Hg(II). The analytical utility of this membrane was established by using it as an indicator electrode in electrometric titrations.     

Preparation,characterization, and kinetic evaluation of dendrimer-derived bimetallic Pt–Ru/SiO2 catalysts

A series of silica-supported Pt, Ru, and Pt–Ru catalysts has been synthesized using dendrimer–metal nanocomposite (DMN) precursors prepared by both co- and sequential complexation with metal salts. The catalysts have been characterized by several techniques, including electron microscopy, temperature-programmed titration of adsorbed oxygen, and X-ray diffraction. Liquid-phase selective hydrogenation of 3,4-epoxy-1-butene (EpB) was used as a probe reaction to evaluate their catalytic performance. The bimetallic catalyst prepared by the co-complexation method exhibits a superior catalytic activity compared to the sequential one, and is much more active than a conventional catalyst prepared by incipient wetness. The activity enhancement is attributed to a bifunctional performance of the PtRu alloy sites created, based on a strong correlation between turnover frequencies, and both the alloy compositions and metal surface site distributions. In addition, the co-complexation catalyst is selective toward crotonaldehyde, suggesting that this reaction pathway is favored on the PtRu sites.