碱土铝酸盐长余辉发光材料的有机包覆及其表征

碱土铝酸盐长余辉发光材料的有机包覆及其表征;发光粉;包覆;甲基丙烯酸甲酯;硅烷偶联剂     

功能性硅烷在纳米氧化硅表面的自组装

在分散体系中,两种功能性硅烷,甲基丙烯酰氧丙基三甲基硅烷(MPTES)和氨丙基三甲基硅烷(APTES)在纳米氧化硅表面形成自组装单分子层,用XPS 和FTIR对所得自组装单分子层进行了表征.元素分析结果表明,所得功能性纳米氧化硅中的功能基含量分别为1.03 mmol/g甲基丙烯酰氧基/丙烯酰氧丙基纳米氧化硅(MPSN)和3.34 mmol/g氨基/氨丙基纳米氧化硅(APSN).LSS 分析结果表明,未修饰纳米氧化硅、 MPSN和APSN在甲苯分散体系中的平均流体力学直径大约分别为240、 45和560 nm.     

Swelling Behavior of pH-Sensitive Copolymers Containing 2-Acrylamido-2-Methyl Propane Sulfonic Acid and Acrylic Acid Crosslinked with Vinyl Trimethoxy Silane Crosslinker

Copolymers of 2-acrylamido-2-methyl propane sulfonic acid and acrylic acid were crosslinked in the presence of different mol% of either vinyl trimethoxy silane (VTMS) as the crosslinking agent under acidic conditions or N,N-methylenebisacrylamide (MBA) as crosslinker using solution radical polymerization. The resultant xerogels were characterized by extracting the soluble fractions and measuring the equilibrium water content. Soluble fractions of the crosslinked networks were reduced by varying the MBA and VTMS concentrations. The surface morphology of the crosslinked polymers was observed by scanning electron microscope. The influence of pH on the swelling behavior of gels was investigated. The swelling behaviors of the resulting gels show pH sensitivity.     

Achiral bent-core azo compounds: observation of photoinduced effects in an antiferroelectric tilted smectic mesophase

We report the synthesis and physical properties of four novel bent-core compounds, containing an azo linkage and alkyl terminal chains. It is found that, except for the lowest homologue, all the materials are liquid crystalline, exhibiting columnar or tilted polar smectic phases. In one of the compounds a reversible photoinduced variation of the spontaneous polarization of the antiferroelectric state was observed.     

Surface Modification of Poly(urea-formaldehyde) Microcapsules and the Effect on the Epoxy Composites Performance

The surfaces of poly(urea-formaldehyde) (PUF) were modified by γ -glycidoxypropyltrimethoxy silane (KH560) in order to improve the interfacial bonding between self-healing PUF microcapsules and epoxy matrix. The modification mechanism between PUF microcapsules and KH560 was studied. X-ray photoelectron spectra (XPS) analyses showed that the silane coupling agent molecular binds strongly to the surfaces of PUF microcapsules. Chemical bond (Si–O–C) and hydrogen bond were formed at interface by the reaction between Si–OH and the hydroxyl group of PUF microcapsules surface. The tensile and impact resistance tests revealed that strength and toughness of the composites was improved significantly. Furthermore, scanning electronic microscopy (SEM) photographs of the fractured surface confirmed that the silane coupling agent plays an important role in improving the interfacial performance between microcapsules and resin matrix.     

Modification and Characterization of Chitosan Films Using 3-trimethoxyl Silyl Propylmethacrylate

The biodegradable flexible chitosan film was prepared by solution casting. The physico-mechanical properties, polymer loading (PL), gel content and water uptake of the chitosan film were studied. The tensile strength (TS) and % elongation at break (Eb) of the uncured chitosan film were 7.0 (MPa) and 8%, respectively. Four formulations were developed using 3-trimethoxyl silyl propylmethacrylate (TSPMA) (varied from 10–80% by weight) in methanol along with photoinitator (Darocur-1664). The raw chitosan films were then soaked in the prepared formulations and cured under UV radiation at different intensities to improve the physico-mechanical properties of the films. TS for the photocured chitosan film was 28.0 (MPa) which was 4 times higher compared to the uncured chitosan film. This TS was obtained for the formulation containing 30% silane (TSPMA) at 24th UV pass for 4 min soaking time. The maximum PL of 45.1% was obtained for the same formulation at 24th UV pass for 4 min soaking time. The water uptake and gel content of the photocured chitosan films were also studied. The scanning electron micrographs of the photocured chitosan film showed smooth surface, compact and homogeneous structure.     

Preparation of novel,liquid, solvent‐free,polyolefin‐based adhesives

An innovative procedure for functionalization of polyolefins was developed. It was found that synthesized polyolefins end‐capped with trimethoxysilane (silylated polyolefins) are new polyolefin‐based adhesives. To prepare the mentioned materials,1‐octene as a higher α‐olefin was cooligomerized with two linear, nonconjugated dienes (ie, 1,5‐hexadiene and 1,7‐octadiene) by using metallocene catalyst system, Cp₂HfCl₂/MAO, at room temperature. Then, amine‐terminated trimethoxysilane (3‐aminopropyltrimethoxysilane) was reacted with unsaturated bonds of synthesized cooligomers in the presence of palladium(II) acetate. Embedding of the dienes on 1‐octene oligomeric chains was explored by Fourier transform infrared (FTIR), ¹H, and ¹³C‐NMR spectroscopy. On the basis of the results, 1,5‐hexadiene showed both 1‐butene branch and five‐member ring. On the other hand, 1,7‐octadiene was incorporated by 1,2‐addition, forming both 1‐hexene branch and seven‐member ring in the cooligomer backbone. Mole percentage of C?C and cyclic moieties reached to a value of 28.54, 18.59% mol in 1‐octene/1,5‐hexadiene, and 38.04, 6.71% mol in 1‐octene/1,7‐octadiene cooligomers, respectively. Reaction of synthesized cooligomers with 3‐aminopropyltrimethoxysilane was confirmed by FTIR spectroscopy, which yielded targeted adhesives. To study the adhesion properties, resulting adhesives were applied to different substrates. Obtained results demonstrated that tensile shear strength of synthesized adhesives to polar substrates was 2.21% to 2.84% more than nonpolar substrates. Among studied systems, the best performance was achieved by1‐octene/1,7‐octadiene–based adhesive and Al substrate with tensile shear strength of 1.45 N/mm².     

Iridium‐Catalyzed Regioselective Silylation of Aromatic and Benzylic CH Bonds Directed by a Secondary Amine

Reported herein is an iridium‐catalyzed, regioselective silylation of the aromatic C? H bonds of benzylamines and the benzylic C? H bonds of 2,N‐dialkylanilines. In this process, (hydrido)silyl amines, generated in situ by dehydrogenative coupling of benzylamine or aniline with diethylsilane, undergo selective silylation at the C? H bond γ to the amino group. The products of this silylation are suitable for subsequent oxidation, halogenation, and cross‐coupling reactions to deliver benzylamine and arylamine derivatives.     

Analytical methods for airborne arsine,silane and dichlorosilane by adsorption sampling and AA spectrophotometry

Analytical methods for arsine, silane and dichlorosilane by adsorption sampling and elemental analysis with graphite furnace AA were studied to establish convenient methods for atmospheric contamination surveys. This study included the following five items: (1) primary selection of adsorbents applicable to adsorption sampling; (2) examination of the adsorption capacities of the adsorbents for the gases; (3) improvement of the adsorbents by chemical modification; (4) desorption of the gases adsorbed on the adsorbents with solvents; and (5) quantitative analysis of arsenic and silicon in the solutions. Experimental results showed that active carbon made from synthetic thermosetting resin beads contained no aresenic and little silicon as impurities. This active carbon by itself was proved to adsorb arsine and dichlorosilane, but not silane. Impregnation with sodium hydroxide of the active carbon improved the adsorption capacity for all three gases. Refined silica gel, free from arsenic contamination, did not adsorb arsine by itself but potassium permanganate impregnation produced an adsorption capacity for arsine. The adsorbed arsine on the active carbon was desorbed into a hot dilute nitric acid solution with high efficiency (over 90%), but arsine adsorbed on sodium hydroxide impregnated active carbon or on potassium permanganate impregnated silica gel was dissolved into various solutions only at lower efficiencies. Silane adsorbed on sodium hydroxide-impregnated active carbon was desorbed with hot water with an efficiency higher than 90%. Dichlorosilane adsorbed on the active carbon with or without sodium hydroxide impregnation was desorbed with a nitric acid solution with efficiency of 85%. The lower determination limit for arsine able to discriminate from background interference of arsenie was 0.005 ppm, and those for silane and dichlorosilane were each 0.05 ppm for 3-dm³ air samples.