Amino acids and peptides. XXXVIII. Facile synthesis of laminin-related peptide-poly(ethylene glycol) hybrids by the solid phase method

Poly(ethylene glycol) (PEG) has been studied as a drug-carrier for proteins, but not for small peptides. Laminin, a cell adhesive protein, has Tyr-Ile-Gly-Ser-Arg (YIGSR) sequence and peptides containing this sequence inhibit experimental metastasis. We have studied PEG hybrids of YIGSR and other small laminin-related peptides. In a previous paper, we reported preparation of YIGSR-PEG hybrids by combination of the solid phase method and the solution method, but the synthetic procedure was problematic. Here we report a facile synthesis of PEG hybrids of YIGSR (PEG-YIGSR, YIGSR-PEG, PEG-YIGSR-PEG) by the solid phase method.     

Preparation of polythiophene/WO_3 organic-inorganic hybrids and their gas sensing properties for NO_2 detection at low temperature

Polythiophene/WO3(PTP/WO3)organic-inorganic hybrids were synthesized by an in situ chemical oxidative polymerization method,and char- acterized by X-ray diffraction(XRD),transmission electron microscopy(TEM)and thermo-gravimetric analysis(TGA).The Polythiophene/ WO3 hybrids have higher thermal stability than pure polythiophene,which is beneficial to potential application as chemical sensors.Gas sensing measurements demonstrate that the gas sensor based on the Polythiophene/WO3 hybrids has high response and good selectivity for de- tecting NO2 of ppm level at low temperature.Both the operating temperature and PTP contents have an influence on the response of PTP/WO3 hybrids to NO2.The 10 wt%PTP/WO3 hybrid showed the highest response at low operating temperature of 70-C.It is expected that the PTP/WO3 hybrids can be potentially used as gas sensor material for detecting the low concentration of NO2 at low temperature.     

Cobalt-mediated approach for the synthesis of terpene-based hybrids

[structure: see text] Dicobalt-beta-pinene hybrids of types I and II have been prepared using a Nicholas reaction between propargyl derivatives, obtained from commercial (1R)-(-)-myrtenal, and different aromatic nucleophiles. The method is suitable for the preparation of densely functionalized bio-organometallic natural product-based hybrids, as demonstrated by the preparation of a beta-pinene-neoclerodane hybrid.     

High efficiency synthesis of octavinylsilsesquioxanes and its high performance hybrids based on bismaleimide‐triazine resin

An improved method is developed to synthesize octavinylsilsesquioxanes (VPOSS) with shorter time and higher yield, and then VPOSS is used to prepare new hybrids based on bismaleimide‐triazine (BD/CE) resin, coded as VPOSS/BD/CE. The effect of the content of VPOSS on the key properties including curing behavior, thermal, mechanical, and dielectric properties as well as water resistance of VPOSS/BD/CE hybrids were systematically discussed. Compared with BD/CE resin, hybrids show similar curing behavior but different chemical structures and thus macro‐performance. These key properties of hybrids are dependent on the content of VPOSS, all hybrids show significantly improved dielectric properties, water resistance, and dimensional stability; moreover, the hybrids with suitable content of VPOSS have bigger impact strengths. Specifically, with the addition of 7 wt% VPOSS to BD/CE resin, the dielectric constant decreases from 3.7 to 3.2, the dielectric loss decreases 55%, and the coefficient of thermal expansion reduces 23%; moreover, the glass transition temperature and initial decomposition temperature increase about 15°C. The attractive integrated properties suggest that VPOSS/BD/CE hybrids have great potential to be used as structural and functional materials for many cutting‐edge fields. Copyright © 2011 John Wiley & Sons, Ltd.     

Homogeneous anionic PPE hybrids with silica gel

Anionic poly(p‐phenylene‐ethynylene) (PPE) incorporated polymer hybrids were synthesized from the PPE and tetramethoxysilane together with the organic polymers such as poly(vinylpyrrolidone) via a sol–gel method. Up to 10 wt % of the anionic PPE could be dispersed homogeneously in the resulting polymer hybrid matrix. The obtained polymer hybrids exhibited controllable photoluminescence properties by the modification of the internal environment of organic–inorganic polymer hybrids by changing the organic/inorganic ratios. The photoluminescence of the anionic PPE surrounded by the polymer hybrid matrix was reinforced against the thermal irradiation. Moreover, the photoluminescence of the obtained organic–inorganic polymer hybrids was also tuned by utilizing ionic interactions between the anionic PPE and the inorganic matrix. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3749–3755, 2008     

Polyurethane–nanosilica hybrid nanocomposites synthesized by frontal polymerization

Polyurethane–nanosilica hybrids were synthesized with frontal polymerization. Structurally well‐dispersed and stable hybrids were obtained via a two‐step functionalization process: First, the silica was encapsulated with 3‐aminopropyltriethoxysilane (APTS). Second, poly(propylene oxide) glycol, toluene 2,4‐diisocyanate, 1,4‐butanediol, and a catalyst (stannous caprylate) were dissolved in dimethylbenzene and mixed together at room temperature along with the modified nanosilica. A constant‐velocity propagating front was initiated via the heating of the end of the tubular reactor. For the complete encapsulation of the silica with APTS, different weight ratios of APTS to silica were investigated. The polyurethane hybrids were characterized with Fourier transform infrared, differential scanning calorimetry, and transmission electron microscopy. The polyurethane hybrids produced by frontal polymerization had the same properties as those produced by batch polymerization with stirring, but the frontal polymerization method required significantly less time and lower energy input than the batch polymerization method. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1670–1680, 2005     

Preparation and characterization of silver-modified poly(vinyl alcohol)/polyethyleneimine hybrids as a chemical and biological protective material

Nanohybrid membranes based on the silver (Ag) and a poly(vinyl alcohol)/polyethyleneimine (PVA/PEI) blend were prepared by an in-situ reduction method, in which the silver nitrate, PVA and PEI acted as precursor, linker and polyamine reductant, respectively. The objective of the study was to develop and evaluate permeable membranes (PVA/PEI) impregnated with Ag nanoparticulates that can protect against simulants of chemical and biological warfare agents. The physical properties of the PVA/PEI-Ag hybrids were examined using SEM, TEM, TGA, and UV-vis spectroscopy, the results indicated that the Ag was incorporated in the PVA/PEI matrix after impregnation. The Ag content and surface morphology of the PVA/PEI-Ag hybrids depended on the initial concentration of AgNO₃. The chemical barrier properties against 2-chloroethyl-ethyl sulfide (CEES) were investigated based on static-diffusion method with gas chromatograph (GC). The antibacterial effects of the PVA/PEI-Ag hybrids were assessed by the zone of inhibition, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and plate-counting methods. The results of this study showed that PVA/PEI-Ag hybrids that act against simulants of chemical and biological weapons while retaining their ability to transmit moisture vapor could be obtained.     

Controllable synthesis of functionalized CdS nanocrystals and CdS/PMMA nanocomposite hybrids

We reported controllable synthesis of CdS nanocrystal-polymer transparent hybrids by using polymethylmethacrylate (PMMA) as a polymer matrix. In a typical run, the appropriate amounts of cadmium chloride (CdCl₂) and sodium sulfide (Na₂S) in the presence of 2-mercaptoethanol (ME) as the organic ligand are well dispersed in H₂O/DMF solution without any aggregation. From a combination of transmission electron microscopy (TEM) and a computing method of Brus’s model according UV-vis absorption spectra, the particle size of as-prepared hydroxyl-coated CdS nanocrystal was determined to be about 5 nm. Then, with the surface treatment with methacryloxypropyltrimethoxysilane (MPS), CdS-PMMA hybrids were obtained via free radical polymerization in situ. FT-IR characterization indicates the formation of robust bonding between CdS nanocrystals and the organic ligand and the formation of double-bond functional CdS nanocrystals. The TGA measurement displays CdS-PMMA hybrids possess better thermal stability compared with pure PMMA polymer. The fluorescence measurement shows that CdS nanocrystals and CdS-PMMA hybrids exhibit good optical properties. Also, the luminescent photographs taken under ultraviolet light prove the luminescence properties.     

Covalently Linked,Transparent Silica–Poly(imide) Hybrids

Silica–poly(imide) hybrid materials have been developed which rely on interactions between the organic and inorganic phases to improve homogeneity. Using this method, transparent hybrids have been formed over all compositions studied. The hybrids show improved hardness and modulus with increasing silica content. Links between the two phases result in very finely divided microstructures. Hybrids such as these might be very important as barrier layers or scratch-resistant coatings. © 1997 John Wiley & Sons, Ltd.     

Synthesis of mesoporous silica and its modification of bismaleimide/cyanate ester resin with improved thermal and dielectric properties

A novel method is proposed to synthesize new mesoporous silica containing amine groups (MPSA), and it was further employed to modify bismaleimide‐dialllyl bisphenol (BD)/cyanate ester (CE) resin to form novel MPSA/BD/CE hybrids; in addition, the typical properties of MPSA/BD/CE were systematically investigated. Results show that these hybrids have very low dielectric constant and loss as well as good thermal properties. Compared with BD/CE resin, all hybrids have not only decreased dielectric constant and loss but also similar dependence of dielectric properties on frequency over the whole frequency from 10 to 10⁶ Hz. Specifically, with the addition of MPSA to BD/CE resin, the dielectric constant reduces from 3.5 to 3.0, and the dielectric loss is only 85% of that of BD/CE resin. Note that all hybrids show better thermal resistance (reflected by higher glass transition temperature, decreased maximum degradation rate, and higher char yield at 800°C) than BD/CE resin. All these differences in macro‐properties are attributed to the different structure between MPSA/BD/CE hybrids and BD/CE resin. Copyright © 2011 John Wiley & Sons, Ltd.     

Effects of inorganic components on the structure and thermo-oxidative degradation of PMMA modified metal alkoxide–EAA complex

Poly(methyl methacrylate) (PMMA) modified titanium and zirconium n-butoxide–ethyl acetoacetate (EAA) complex [M5-Ti(OBuⁿ)₂(EAA)₂ and M5-Zr(OBuⁿ)₂(EAA)₂] were obtained from trialkoxysilane-functional PMMA and EAA modified titanium and zirconium alkoxide via the sol–gel method. Infrared (IR), ¹³C nuclear magnetic resonance (NMR) spectroscopy, and thermogravimetric analysis (TGA) were used to analyze the structures and properties of the hybrids with various proportions of metal oxide species. The effect of the complex of metal oxides and EAA ligands on structure and thermo-oxidative degradation of the M5-Ti(OBuⁿ)₂(EAA)₂ and M5-Zr(OBuⁿ)₂(EAA)₂ hybrids were investigated in this study. The ¹H spin–diffusion path length of the hybrids was in a nanometer scale as estimated from the spin–lattice relaxation time in a rotating frame (T_1ρ^H). The apparent activation energies (E_a), evaluated by van Krevelen’s method, for random scission of PMMA segments in hybrids decreased with increasing metal oxide content.     

Copper(II)-mediated layer-by-layer assembly of viologenthiol-functionalized carbon nanotube hybrid multilayers: preparation, characterization, morphology, and electrochemical properties

The metal-mediated self-assembly of coordination polymers, building blocks, and metal-organic frameworks has been widely used to construct multifunctional novel materials on the molecular level. Here, we developed this technique to build up multilayers of functionalized carbon nanotubes on the basis of both intermolecular electrostatic and coordinative interactions. Positively charged electroactive viologenthiol (VSH) was first immobilized on multiwalled carbon nanotubes (MWNTs) to form MWNT-VSH hybrids with a relative content of ～9% by weight. Field emission transmission electron microscopy images revealed that the VSH molecules randomly covered the surfaces of MWNTs with a thickness of 1 to 2 nm. Then, the MWNT-VSH hybrids were used as nanoscale multidentate "ligands" (linkers) to construct metal-mediated multilayers with the use of CuAc(2) as the connectors by the layer-by-layer (LBL) method. The assembly process was monitored by absorption and X-ray photoelectron spectroscopy as well as scanning electron and atomic force microscopy after each assembly of Cu(II) ions and MWNT-VSH hybrids. Finally, the electrochemical behaviors of the viologens in the MWNT-VS/Cu LBL multilayers were investigated.     

Solventless silicone hybrids based on polyhedral oligomeric silsesquioxane and hyperbranched polysiloxane for vacuum pressure impregnation process

A novel kind of solventless silicone hybrids (SSiH) containing branched poly(methylphenylvinylsiloxane) (PMPVSi), end‐capped hydrogen‐functionalized hyperbranched polysiloxane (EHFHPSi), and octavinyl‐polyhedral oligomeric silsesquioxane (OVPOS) was developed through a hydrosilylation reaction. Each of the three basic components was synthesized by harmless and recyclable methods. The new hybrids are considerably suitable for vacuum pressure impregnation process, and can serve as an excellent class C insulating material. The effect of differing stoichiometries of OVPOS and EHFHPSi on the performance of cured hybrids is discussed. Results show that SSiH hybrids possess excellent dielectric and thermal properties as well as low viscosity. The reduction in the dielectric constant and the improvement of thermal property of SSiH hybrids can be explained by the unique structure and morphology of hybrids resulting from the presence of OVPOS and EHFHPSi. The novel silicone hybrids exhibit great potential to be used for many cutting‐edge industries, especially the microelectronic and insulation fields. Copyright © 2010 John Wiley & Sons, Ltd.     

Preparation of Bioactive PDMS-Modified CaO–SiO2–TiO2 Hybrids by the Sol-Gel Method

Much attention has been focused on the development of a new type of bioactive material with mechanical properties analogous to those of natural bone. The present authors previously showed that some polydimethylsiloxane (PDMS)-modified CaO–SiO₂–TiO₂ hybrids prepared by sol-gel method show apatite-forming ability in a simulated body fluid (SBF), which is indicative of bioactivity. In the present study, effects of composition of PDMS-modified CaO–SiO₂–TiO₂ hybrids on their bioactivity and mechanical properties were investigated. The bioactivity of the hybrids increased with decreasing PDMS content and increasing TiO₂ content. Their strain at failure increased with increasing PDMS content and decreasing TiO₂ content. Some samples showed high bioactivity, as well as analogous mechanical properties to those of human cancellous bones. This type of hybrids might be useful as a bone-repairing material.     

层状类钙钛矿结构有机-无机杂合物(RNH3)2CuCl4的制备及表征

以氯化铜(CuCl2)为研究对象,通过变换有机元制备了3种结构相似的层状类钙钛矿结构的有机-无机杂合物.用扫描电子显微镜(SEM)、X射线衍射分析(XRD)和FT-IR分别对这3种杂合物的无机元、有机元和晶体结构以及各组分问的相互作用进行分析.实验结果表明,当有机元为链状烷基胺时,层状结构非常明显,而当有机元为带刚性苯...     

Solution-phase synthesis of branched DNA hybrids based on dimer phosphoramidites and phenolic or nucleosidic cores

Branched oligonucleotides with "CG zippers" as DNA arms assemble into materials from micromolar solutions. Their synthesis has been complicated by low yields in solid-phase syntheses. Here we present a solution-phase synthesis based on phosphoramidites of dimers and phenolic cores that produces six-arm or four-arm hybrids in up to 61% yield. On the level of hybrids, only the final product has to be purified by precipitation or chromatography. A total of five different hybrids were prepared via the solution-phase route, including new hybrid (TCG)(4)TTPA with a tetrakis(triazolylphenyl)adamantane core and trimer DNA arms. The new method is more readily scaled up than solid-phase syntheses, uses no more than 4 equiv of phosphoramidite per phenolic alcohol, and provides routine access to novel materials that assemble via predictable base-pairing interactions.     

溶胶-凝胶法制备聚醚砜-二氧化硅复合材料

以聚醚砜(PES)为基体,通过溶胶-凝胶过程,得到了分散均匀的PES/SiO₂杂化材料,用扫描电镜、透射电镜、傅里叶红外及差示扫描量热法研究不同SiO₂含量的PES/SiO₂杂化材料材料性能.结果表明,当PES/SiO₂杂化材料中SiO₂的质量分数大于10%时可获得有机聚合物链段与无机网络互穿的均匀分散的复合材料.此材料的玻璃化转变温度(Tg)明显提高.     

溶剂热法制备四氧化三铁/聚乙烯亚胺修饰的多壁碳纳米管复合粒子及其吸波性能

采用溶剂热法将磁性Fe_3O_4粒子附着在聚乙烯亚胺(PEI)修饰的多壁碳纳米管(MWNTs)表面,制备了兼具介电损耗和磁损耗的复合吸波微粒Fe_3O_4/MWNTs。利用X射线衍射仪(XRD)、傅里叶红外光谱仪(FTIR)、热重分析仪(TGA)、透射电子显微镜(TEM)及矢量网络分析仪等分析了Fe_3O_4/MWNTs复合粒子的结构、形貌和吸波性能。TEM结果表明,由于PEI的修饰作用,Fe_3O_4/MWNTs复合粒子具有良好的分散性。XRD结果显示,附着的Fe_3O_4粒子具有完整的晶型结构。吸波性能结果表明,PEI修饰的Fe_3O_4/MWNTs复合微粒拥有非常优异的吸波性能,随着厚度的增加,复合微粒的吸收峰向低频处移动。在厚度为3.2 mm,频率为6.16 GHz时,出现了最大反射损耗-42.9 d B,反射损耗大于-10 d B的频段为1.42 GHz(5.40~6.82 GHz)。     

Study on thermal degradation and combustion behaviors of PC/POSS hybrids

Polycarbonate/polyhedral oligomeric silsesquioxane hybrids were prepared based on bisphenol A polycarbonate (PC) and trisilanolphenyl-POSS (TPOSS) by the melt blending method. Investigation of transmission electronic microscopy and Fourier transform infrared spectroscopy confirms that the nanoscale TPOSS particles were well dispersed in the PC matrix and there is no chemical reaction between the TPOSS particles and PC matrix during the melt blending. The thermal degradation behaviors of the PC/TPOSS hybrids were investigated. The presence of TPOSS significantly affects the thermal degradation process of PC. The combustion behaviors of the hybrids were evaluated by cone calorimetry experiments. The addition of TPOSS significantly decreased the value of peak heat release rate of the hybrids. Moreover, the addition of TPOSS at 2 wt% leads to the maximum decrease of the PHRR. And scanning electron microscopy and X-ray photoelectron spectroscopy were used to explore the char residues of the pure PC and the hybrids.     

Hybrid materials for solid-state dye laser applications

The quest for a solid-state tunable dye laser can be satisfied by sol-gel prepared organic-inorganic hybrids. A photostability study of porous silica-Rhodamine 6G hybrids prepared via a sol-gel method is presented. The dye molecules can be incorporated into the silica matrix by forming weak or covalent bonds (hybrids of classes I and II, respectively). New class II samples and traditional class I materials prepared by the pre-doping method were synthesized. Samples were characterized by photoluminescence measurements to compare the emission properties and the photostability of the samples. The decay of the fluorescence signal as the cumulative excitation energy increases is reported and interpreted by hypothesizing that the dye molecules can be hosted in different surroundings within the porous glass matrix. The reported photoluminescence and photobleaching features indicate the class II samples as good candidates for solid-state dye lasers.