Sol-gel derived hard optical coatings via organic/inorganic composites

Hard optical coatings via TiO₂/organically modified silane composites have been prepared by the sol-gel technique using γ-Glycidoxypropyltrimethoxysilane (GLYMO, used as organically modified silane source) and tetrapropylorthotitanate (TPOT, used as TiO₂ source) as precursors. Scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy have been used to investigate the morphology and structural properties of the coatings. The hardness and Young's modulus of the coatings have been characterized by a Nanoindenter and found to depend on the heat-treatment temperature and titanium content. Hardness as high as 10 Gpa was achieved at a heat-treatment temperature of 1000 °C. It was proposed that the high hardness of the coating is related to the carbon and titanium content in the coating.     

Hybrid organic/inorganic composites based on silica and weak synthetic polyelectrolytes

The preparation and characterization of new organic/inorganic composites by the consecutive adsorption of weak polyelectrolytes on silica particles were studied in the article. Two polycations containing primary amine groups in the side chains, poly(vinylamine) or poly[N(β-aminoethylene) acrylamide], and poly(acrylic acid) as polyanion were used for the hybrid materials construction. The stability of the organic/inorganic composites has been increased by a heat-induced reaction at 150 °C. The organic/silica hybrids properties were monitored by potentiometric titration, laser light scattering, infrared spectroscopy, and thermogravimetric analysis. The adsorption of methylene blue by the composite materials has been tested. The dye adsorption capacity was strongly influenced by the dye concentration, the nature of the last adsorbed layer, the polyions concentration, and the composite thermal treatment.     

Hydrogel/bioactive glass composites for bone regeneration applications: Synthesis and characterisation

Due to the deficiencies of current commercially available biological bone grafts, alternative bone graft substitutes have come to the forefront of tissue engineering in recent times. The main challenge for scientists in manufacturing bone graft substitutes is to obtain a scaffold that has sufficient mechanical strength and bioactive properties to promote formation of new tissue. The ability to synthesise hydrogel based composite scaffolds using photopolymerisation has been demonstrated in this study. The prepared hydrogel based composites were characterised using techniques including Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy-dispersive X-ray spectrometry (EDX), rheological studies and compression testing. In addition, gel fraction, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), porosity and swelling studies of the composites were carried out. It was found that these novel hydrogel bioglass composite formulations did not display the inherent brittleness that is typically associated with bioactive glass based bone graft materials and exhibited enhanced biomechanical properties compared to the polyethylene glycol hydrogel scaffolds along. Together, the combination of enhanced mechanical properties and the deposition of apatite on the surface of these hydrogel based composites make them an ideal candidate as bone graft substitutes in cancellous bone defects or low load bearing applications.     

稀土乙酸8-羟基喹啉三元配合物/羟基磷灰石的纳米有机/无机主客体组装复合抗菌生物材料

采用湿法原位合成了Tb、Y、Gd 3种稀土乙酸8-羟基喹啉三元配合物与羟基磷灰石的纳米有机/无机主客体组装复合材料。通过扫描电子显微镜、X射线粉末衍射、红外光谱对样品进行结构分析测定;采用最低抑菌浓度(MIC)和最低杀菌浓度(MBC)实验来检测其抗菌能力。结果表明,  3种复合材料纳米晶平均粒径为50～60 nm,皆对金黄葡萄球菌和大肠杆菌具有较高的抗菌作用,并对金黄葡萄球菌的抑制作用强于大肠杆菌。经过对3种复合材料抗菌作用的比较得出抗菌能力的次序为：  Tb-HQ/HAP < Y-HQ/HAP < Gd-HQ/HAP。     

Synthesis, neutralization and blocking procedures of organic/inorganic hybrid scaffolds for bone tissue engineering applications

Bioactive glasses (BaG) can bind to human bone tissues and have been used in many biomedical applications for the last 30 years. However they usually are weak and brittle. On the other hand, composites that combine polymers and BaG are of particular interest, since they often show an excellent balance between stiffness and toughness. Bioactive glass-poly(vinyl alcohol) foams to be used in tissue engineering applications were previously developed by our group, using the sol-gel route. Since bioactive glass-polymer composite derived from the sol-gel process cannot be submitted to thermal treatments at high temperatures (above 400 degrees C), they usually have unreacted species that can cause cytotoxicity. This work reports a technique for stabilizing the sol-gel derived bioactive glass/poly(vinyl alcohol) hybrids by using glutaraldehyde (GA), NH(4)OH solutions and a blocking solution containing bovine serum albumin. PVA/BaG/GA hybrids were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM/EDX) analyses. Moreover, MTT (3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide) biocompatibility and cytotoxicity assays were also conducted. The hybrids exhibited pore size varying from 80 to 820 mum. After treatments, no major changes in the pore structure were observed and high levels of cell viability were obtained.     

含硅有机/无机纳米杂化材料

综述了由有机硅氧烷制备有机/无机材料的sol gel方法,介绍了由此得到的杂化材料在光电材料、高性能陶瓷和聚合物以及其它功能性材料等方面的应用,并对新的sol gel原料作了展望。     

Relationship between microstructure and fracture behavior of bioabsorbable HA/PLLA composites

Hydroxyapatite particles of four different shapes, that is, micro, nano, spherical and plate, were used to fabricate hydroxyapatite filled poly(l-lactic acid) (HA/PLLA) composites. Effects of HA particle shape on the fracture behavior of HA/PLLA were investigated by mode I fracture testing, fracture surface measurement and scanning electron microscopy. It was found that the micro-HA/PLLA has the highest critical energy release rate, G_IC, with the largest surface roughness, while G_IC of the nano-HA/PLLA was lowest corresponding to the smallest surface roughness. The micro-HA/PLLA composites exhibited interfacial debonding and local ductile deformation of the PLLA matrix, indicating higher fracture energy and therefore, the highest G_IC. On the other hand, the nano-HA/PLLA composites showed brittle fracture surface due to nano-scale interaction between PLLA fibrils and primary HA particles, corresponding to lower fracture energy and hence the lowest G_IC.     

Pulsed X-ray luminescence of composites consisting of inorganic particles and organic phosphors

A fast luminescence component with a duration of ??2 ns has been observed upon pulsed X-ray excitation of composites composed of microparticles of a heavy constituent (heavy-metal oxides and fluorides) and optically active polymer adhesive. The intensity and temporal parameters of this component depend on neither the structural state of the heavy constituent nor the presence of optically active impurity. A mechanism of the formation of the fast luminescence component of composites upon pulsed X-ray excitation is proposed; according to it, when high-energy X rays interact with the heavy constituent of the composite, electrons and low-energy X-ray photons, which are intensely absorbed by the polymer adhesive and thus cause its luminescence, are generated due to the photoelectric effect and X-ray scattering.     

Soundproofing effect of polypropylene/inorganic particle composites

Two inorganic particle-filled polypropylene (PP) composites including PP/hollow glass bead (HGB) composite and PP/nanometer calcium carbonate (nano-CaCO₃) composite were prepared by means of a twin-screw extruder in the present paper. The transmission loss was measured, to identify the effects of sound frequency and the filler content on the sound insulation properties of these filled systems. The results showed that the sound insulation effect of the PP/nano-CaCO₃ obeyed roughly the law of mass, the transmission loss of the two composites increased nonlinearly with an increase of the filler volume fraction, and the value of the transmission loss for the PP/HGB system was higher than that of the PP/nano-CaCO₃ system under the same level of sound frequency. The transmission loss increased roughly with an increase of sound frequency for the two composites except to individual sound frequency. The mechanisms of the sound insulation of these composites were discussed.     

A novel approach of homogenous inorganic/organic composites through in situ precipitation in poly-acrylic acid gel

A new in situ precipitation technique was developed to promote high-affinity nucleation and growth of calcium phosphate in the polymer hydrogel. Poly-acrylic acid/ hydroxyapatite (HAP) composites have been prepared using template-driven reaction. Nano-sized hydroxyapatite particles were distributed within organic template homogenously, furthermore, inorganic particles were fine and uniform. A kind of specific product with the characteristic of fractal was also obtained. During the composite process, 3D network of organic matrices played an important role in the superfine interaction of HAP and hydrogel through the compartment-effect of interior of hydrogel. This method provides an efficient approach toward inorganic/organic nanocomposites with high-uniformity decentralization for biomimetic replant applications. This paper discussed the mechanism of compartment-effect, and the concept of in situ precipitation in gel was brought forward. SEM and TEM were employed in the analysis of the morphological characteristic of uniform inorganic/organic composites and inorganic minerals separated from organic template. SEM-associated EDS area analysis and TEM-associated EDS analysis were employed in the analysis of component characteristic of inorganic/organic composite and inorganic particles. X-ray diffraction was employed in the analysis of precipitation phase crystal structure of inorganic component.     

In vivo bone regeneration with injectable chitosan/hydroxyapatite/collagen composites and mesenchymal stem cells

For reconstruction of irregular bone defects, injectable biomaterials are more appropriate than the preformed biomaterials. We herein develop a biomimetic in situ-forming composite consisting of chitosan (CS) and mineralized collagen fibrils (nHAC), which has a complex hierarchical structure similar to natural bone. The CS/nHAC composites with or without mesenchymal stem cells (MSCs) are injected into cancellous bone defects at the distal end of rabbit femurs. Defects are assessed by radiographic, histological diagnosis and Raman microscopy until 12 weeks. The results show that MSCs improve the biocompatibility of CS/nHAC composites and enhance new bone formation in vivo at 12 weeks. It can be concluded that the injectable CS/nHAC composites combined with MSCs may be a novel method for reconstruction of irregular bone defects.     

自组装制备有机/无机层状复合材料

自然界中形成的生物材料在结构和性能上具有优异的配备性。模仿生物矿化的形成机制,利用自组装原理能够仿生合成出性能优良和具有多级结构特点的有机/无机界面层状复合材料。本文在总结近年来最新研究的成果上,简要介绍了自组装和生物矿化的机理,重点阐述了基于无机相层的自组装和以有机大分子为模板自组装制备有机／无机层状复合材料两种合成连径,并对未来的发展趋势做了展望。     

Strengthening masonry vaults with organic and inorganic composites: An experimental approach

Polymer-reinforced fibers are now commonly applied to buildings for structural retrofitting purposes. These materials add greater tensile strength to structures, at the expense of a slight increase in weight. However, they also have other disadvantages such as brittle behavior and lack of water vapor permeability, which are not desired in the conservation of heritage buildings.Alternative composite materials embedded in an inorganic matrix are presented, which solve some of the drawbacks associated with organic matrices. Long steel fibers and basalt textiles are applied to the resistant core of the inorganic matrix to produce a steel-basalt reinforced mortar-based composite. Firstly, a mechanical characterization of the individual components and the resulting material was performed. Secondly, non-strengthened and strengthened real-scale (2.98 m span, 1.46 m high and 0.77 m deep) brick masonry vaults were tested up to failure, in order to demonstrate the mechanical effectiveness of these composite materials. Finally, a comparison between two mortar composite materials (steel-strips/basalt-textiles embedded in a polymer matrix) was performed, with the same real-scale brick-vault failure tests.The experimental campaign demonstrates that the steel/basalt composite mortar is a feasible alternative, which is physically compatible with masonry structures, easy to apply, and effective for the reinforcement of brick vaults.     

ZnO-nanowires/PANI inorganic/organic heterostructure light-emitting diode

In this paper, we report a flexible inorganic/organic heterostructure light-emitting diode, in which inorganic ZnO nanowires are the optically active components and organic polyaniline (PANI) is the hole-transporting layer. The fabrication of the hybrid LED is as follows, the ordered single-crystalline ZnO nanowires were uniformly distributed on flexible polyethylene terephthalate (PET)-based indium-tin-oxide-coated substrates by our polymer-assisted growth method, and proper materials were chosen as electrode and carrier. In this construction, an array of ZnO nanowires grown on PET substrate is successfully embedded in a polyaniline thin film. The performance of the hybrid device of organic-inorganic hetero-junction of ITO/(ZnO nanowires-PANI) for LED application in the blue and UV ranges are investigated, and tunable electroluminescence has been demonstrated by contacting the upper tips of ZnO nanowires and the PET substrate. The effect of surface capping with polyvinyl alcohol (PANI) on the photocarrier relaxation of the aqueous chemically grown ZnO nanowires has been investigated. The photoluminescence spectrum shows an enhanced ultraviolet emission and reduced defect-related emission in the capped ZnO NWs compared to bare ZnO. The results of our study may offer a fundamental understanding in the field of inorganic/organic heterostructure light-emitting diode, which may be useful for potential applications of hybrid ZnO nanowires with conductive polymers.     

有机/无机共混聚丙烯纤维中无机粉体表面处理效果评价

用钛酸酯偶联剂对TiO2 、ZnO等无机粉体表面处理 ,增加其与聚丙烯基体之间的相容性作用 ,并利用沉降体积这一参数对处理效果进行表征 ,讨论了偶联剂用量对处理效果的影响 ,并通过透射电镜观察、评价了无机填料在有机基体中的分散性。     

Bone regeneration using an injectable calcium phosphate/autologous iliac crest bone composites for segmental ulnar defects in rabbits

Background Treatment of segmental bone loss remains a challenge in skeletal repair. A major therapeutic goal is the development of implantable materials that will promote bone regeneration. Objective We evaluate bone regeneration in grafts containing different concentrations autologous iliac crest bone (ACB) particles, carried in a new injectable calcium phosphate cement (CPC), in ulnar bone defects in rabbits. Methods Large upper-mid-diaphyseal defects (10 mm) were created in the left ulnae of 60 skeletally mature New Zealand white rabbits. ACB concentrations of 0, 25, 50, 75, and 100% (by volume) in CPC were used to fill operated sites. Defect bridging was monitored by serial radiography at 4, 8, and 12 weeks post-operation. Samples were then examined histologically and by manual palpation to determine the extent of new bone formation. Results At 4 weeks, we observed more elaborate structures and extensive absorption in ulnae treated with mixtures containing low concentrations of ACB (such as 0% and 25% volume of ACB/CPC), compared with those treated with mixtures containing high concentrations of ACB (such as 75% and 100% volume of ACB/CPC). At 8 weeks, histomorphometry revealed increased trabecular area and volume in the group treated with high ACB concentrations compared with those treated with low ACB concentrations. At 12 weeks, complete cortical bridging and regeneration of marrow space were detected in groups treated with high concentrations of ACB, and the amount of new bone regeneration was greater in these groups than in those treated with low ACB concentrations. Conclusions Treatment of rabbit ulnar defects with injectable CPC carrying an optimized concentration of ACB particles can lead to cortical bridging and bone marrow regeneration within 12 weeks.     

Water treatment via non-membrane inorganic nanoparticles/cellulose composites

Nanomaterials offer innovations in water purification technology with decreased operational and capital cost, reduced dosage, and improved pollutant selectivity. In particular, inorganic nanoparticles (NPs)/cellulose hybrid nanocomposites have attracted growing interest due to the unique properties of cellulose and high specific surface area of NPs and their pollutant selectivity. The integration with cellulose brings benefits to inorganic NPs for water treatment, including preventing agglomeration, ensuring colloidal stability, and allowing for separation by magnetic nanoparticles after purification. In this review, firstly, conventional water treatment technologies are introduced (Section 1). Following this, an overview of inorganic NPs/cellulose composites for water treatment (Section 2) is presented. Moreover, engineering of such hybrid composites is discussed (Section 3). Furthermore, water purification of inorganic NPs/cellulose through adsorption of pollutants (Section 4) and non-adsorption (catalytic, photocatalytic, and antibacterial) activities (Section 5) are highlighted. Finally, conclusions and outlook are provided (Section 6).     

有机/无机支撑复合膜的制备与应用

从有机膜形成方式、有机膜与无机膜界面相互作用等方面对复合膜的制备技术和应用进行了的综述,并讨论了其潜在的发展和应用.