Biocompatible composites of fibrous nanohydroxyapatite embedded in a polydimethylsiloxane

Silicone elastomers have the potential to be a valuable biomaterial due to their mechanical and chemical properties, easy processing, and high gas permeability. Some inherent properties of the pure silicone implant such as high hydrophobicity and low load bearing capacity can be problematic for biomedical applications. The issues were addressed by fabricating hydroxyapatite nanofiber/polydimethylsiloxane nanocomposites. The morphology of nanocomposite structures was visualized by high resolution transmission electron microscopy and field emission scanning electron microscopy. Improved mechanical strength and compliance of the prepared nanocomposite structures were obtained by frequency sweep and creep measurements. Surface hydrophilicity of polydimethylsiloxane was enhanced by hydroxyapatite nanofiber incorporation into the polymer matrix. The cytotoxicity and biocompatibility of the structures were analyzed using breast epithelial cells (MDA MB 231 cell line). These studies showed that the nanocomposite scaffold did not leach any cytotoxic material and showed better cell adhesion and cell proliferation compared to the unfilled elastomer.     

Thermal and rheological properties of biodegradable poly[(butylene succinate)-co-adipate] nanocomposites

The thermal and rheological properties of clay-containing poly[(butylene succinate)-co-adipate] (PBSA) nanocomposites are reported. The nanocomposites of PBSA with various weight percentages of organically modified montmorillonite (OMMT) loadings have been prepared by melt-mixing in a batch-mixer. The melting and crystallization behaviours of PBSA and its nanocomposites have been studied using differential scanning calorimeter (DSC). The melt-state rheological properties of pure PBSA and its nanocomposites containing different amounts of OMMT have been studied in detail. The reason for this is that the rheological responses of any nanofilled polymeric materials are strongly related by their dispersed structure and the interfacial characteristic. Results show that the structural strength of all samples remains constant in the examined time interval at an experimental temperature. The dominant viscous behaviour of pure PBSA is getting suppressed up to a certain OMMT loading (4 wt%). Nanocomposite containing 5 wt% OMMT is showing almost "at the gel point" behaviour, suggesting that the material is behaving near the borderline between liquid and solid; while nanocomposite containing 6 wt% OMMT is showing the gel character. The dispersed structure of the clay particles in the PBSA matrix was studied by scanning transmission electron microscopy (STEM). Results show that the stacked and intercalated silicate layers are nicely dispersed in the case of all nanocomposites. However, with a systematic increase in OMMT loading, the dispersed clay structure of the nanocomposites changes from a highly delaminated to a flocculated and then to a stacked-intercalated structure. In the case of all nanocomposites, melt-state rheological properties are in good agreement with the STEM observations.     

Assessment of rheological and mechanical properties of nanostructured materials based on thermoplastic olefin blend and organoclay

This work aims to assess rheological and mechanical properties of thermoplastic olefin (TPO) nanocomposites reinforced by organo-modified montmorillonite (OMMT). In this regard, TPO/OMMT nanocomposites were produced via melt compounding and characterized in terms of OMMT content and processing parameters. The main objective of the work is to determine the optimum OMMT content and processing parameters. Both dynamic oscillatory and steady shear measurements revealed that a very good degree of OMMT dispersion occurs in the case of nanocomposite containing 3 wt.% OMMT which was also verified by X-ray diffractometry and transmission electron microscopy. Mechanical properties were studied through tensile and impact tests. It was found that as the OMMT content increases, tensile modulus and tensile strength are increased but impact strength is reduced. The optimum properties were observed at 3 wt.% OMMT which is in conformity with the rheological analysis results. As the main processing variables in melt compounding, the effect of mixing time and rotor speed on mechanical properties of TPO nanocomposites were studied and correlated to their rheological properties. It was concluded that using an intermediate mixing time and rotor speed would be more appropriate to achieve desirable mechanical properties.     

PS／OMMT纳米复合材料作为润滑油添加剂的摩擦学性能

用乳液聚合法制备了聚苯乙烯/有机蒙脱土(PS/OMMT)纳米复合材料,并利用 XRD对其结构进行表征.利用四球机考察了纳米复合材料在AN 10油中的摩擦学性能,表明所合成的PS/OMMT纳米杂化材料能提高基础油的抗磨性能及承载能力,降低其摩擦系数;复合材料中OMMT含量对摩擦学性能影响很大.EDX能谱研究结果表明,在低负荷下PS/OMMT纳米复合材料在钢球表面铺展成膜,在高负荷下,聚合物分解,裸露出纳米结构的高度分散蒙脱土片层具有高活性,能在钢球的磨斑表面成膜,改善润滑油高负荷下的摩擦学性能.     

Utilization of natural montmorillonite modified with dimethyl,dehydrogenated tallow quaternary ammonium salt as reinforcement in almond shell flour–polypropylene bio-nanocomposites

The main goal of this work was to evaluate the technical feasibility of almond shell flour (ASF) as wood substitute in the production of wood–plastic composites (WPCs). The effects of organically modified montmorillonite (OMMT), as reinforcing agent, on the mechanical and physical properties were also investigated. In order to improve the poor interfacial interaction between the hydrophilic Lignocellulosic material and hydrophobic polypropylene matrix, maleic anhydride grafted polypropylene (MAPP) was added as a coupling agent to all the composites studied. In the sample preparation, OMMT and ASF contents were used as variable factors. The morphology of the specimens was characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The results of mechanical properties measurements indicated that when 3 wt.% OMMT were added, tensile and flexural properties reached their maximum values. At high level of OMMT loading (5 wt.%), increased population of OMMT lead to agglomeration and stress transfer gets blocked. The addition of OMMT filler decreased the water absorption and thickness swelling of composites. SEM study approved the good interaction of the almond shell flour with the polymer as well as the effectiveness of OMMT in improvement of the interaction. TEM study revealed better dispersion of silicate layers in WPCs loaded with 3 wt.% of OMMT. The improvement of physico-mechanical properties of composites confirmed that OMMT has good reinforcement and the optimum synergistic effect of OMMT and ASF was achieved at the combination of 3 and 50 wt.%, respectively. The findings indicated that almond shell as agro-waste material is a valuable renewable natural resource for composite production and could be utilized as a substitute for wood in composite industries.     

Biocompatibility assessment of SiO2 –TiO2 composite powder on MG63 osteoblast cell lines for orthopaedic applications

The objective of this study is to evaluate the biocompatibility of composite powder consisting of silica and titania (SiO₂ –TiO₂) for biomedical applications. The advancement of nanoscience and nanotechnology encourages researchers to actively participate in reinvention of existing materials with improved physical, chemical and biological properties. Hence, a composite/hybrid material has given birth of new materials with intriguing properties. In the present investigation, SiO₂ –TiO₂ composite powder was synthesised by sol‐gel method and the prepared nanocomposite was characterised for its phase purity, functional groups, surface topography by powder X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR) and scanning electron microscopy. Furthermore, to understand the adverse effects of composite, biocompatibility test was analysed by cell culture method using MG63 osteoblast cell lines as a basic screening method. From the results, it was observed that typical Si–O–Ti peaks in FT‐IR confirms the formation of composite and the crystallinity of the composite powder was analysed by XRD analysis. Further in vitro biocompatibility and acridine orange results have indicated better biocompatibility at different concentrations on osteoblast cell lines. On the basis of these observations, we envision that the prepared silica–titania nanocomposite is an intriguing biomaterial for better biomedical applications.Inspec keywords: bioceramics, nanocomposites, silicon compounds, titanium compounds, nanofabrication, sol‐gel processing, surface topography, X‐ray diffraction, Fourier transform infrared spectra, scanning electron microscopy, X‐ray chemical analysis, cellular biophysics, nanomedicineOther keywords: MG63 osteoblast cell lines, orthopaedic applications, biomedical applications, nanoscience, nanotechnology, nanotoxicology, physical properties, chemical properties, biological properties, biological applications, biomaterial synthesis, composite‐hybrid materials, intriguing properties, sol‐gel method, surface properties, ceramic nanocomposite, phase purity, functional groups, surface topography, powder X‐ray diffraction, Fourier transform infrared spectroscopy, FT‐IR spectroscopy, scanning electron microscopy, energy dispersive X‐ray analysis, biocompatibility test, cell culture method, screening method, crystallinity, XRD, in vitro biocompatibility, acridine orange, silica‐titania nanocomposite powder, SiO₂ ‐TiO₂      

聚氨酯/聚甲基丙烯酸甲酯/有机蒙脱土纳米复合材料的制务、结构与性能

首次将插层纳米复合技术与互穿聚合物网络（IPN）技术相结合,通过同步插层聚合法制备了聚氨酯/聚甲基丙烯酸甲酯/有机蒙脱土（PU/PMMA/OMMT）纳米复合材料.XRD、SEM、TGA等研究表明,在聚氨酯/有机蒙脱土（PU/OMMT）体系中蒙脱土以40～700 nm的团聚体不均匀地分散在聚氨酯基体中,且部分蒙脱土被插层,其层间距增加了0.95nm,体系为插层型纳米复合材料.PU/PMMA/OMMT体系中蒙脱土以20～80nm的粒子分布于聚合物基体中,且蒙脱土的插层效果显著,是PU/OMMT体系的2.5倍,形成了插层型纳米复合材料.同时,蒙脱土的加入使得聚氨酯和聚甲基丙烯酸甲酯的互穿聚合物网络（PU/PMMA-IPN）体系中PU相与PMMA相间相分离更明显,塑性相畴粒子尺寸显著增加,且各相中两组分相互作用加强,分布更均匀.PU/PMMA/OMMT纳米复合材料的热稳定性高于其他材料.同时对其力学性能进行了研究,发现其力学性能明显优于聚氨酯、基于聚氨酯和PU/PMMA-IPN和PU/OMMT纳米复合材料.     

OMMT对PP/PEO合金形态特征与抗静电性能的影响

采用透射电子显微镜(TEM)、扫描电子显微镜(SEM)和热失重分析(TGA)等手段对聚丙烯(PP)/聚氧化乙烯(PEO)/有机蒙脱土(OMMT)复合材料注塑样条断口不同部位材料的组成及聚集态结构进行了研究。结果表明,OMMT选择性分布在PEO分散相中,PP基体中OMMT很少;OMMT的加入导致注塑样条中PEO分散相从表皮层、过渡层到芯层依次出现层状-椭圆状-圆球状形态,OMMT在三个层中的质量分数分别为3.2%、2.4%、1.9%,而PEO的含量分别为21%、17%、15%,PEO和OMMT含量都逐渐降低;OMMT的加入使复合材料的热分解温度提高了30℃、表面电阻率降低到1.6×109Ω。     

PVAc-nano-OMMT/PP-EVA复合材料的制备与性能

利用乳液聚合法引发醋酸乙烯酯(VAc)在有机蒙脱土(OMMT)中原位插层聚合, 与聚丙烯(PP)-乙烯-醋酸乙烯酯共聚物(EVA)复合体系熔融共挤制备出PVAc-nano-OMMT/PP-EVA复合材料。X射线衍射(XRD)与透射电镜(TEM)测试结果表明, 在强剪切作用下, PVAc-nano-OMMT/PP-EVA形成了剥离型纳米复合材料结构; 热失重(TGA)测试结果显示PVAc-nano-OMMT/PP-EVA的起始分解温度明显高于PP-EVA和nano-OMMT/PP-EVA, PVAc-nano-OMMT的存在使材料的热性能得以改善; 在PVAc-nano-OMMT/PP-EVA共混物中, PVAc-nano-OMMT具有明显的增韧作用; 通过氧指数(LOI)和锥形量热(CONE)测试, PVAc-nano-OMMT/PP-EVA的氧指数为24.1%, 可较大幅度地降低材料燃烧的热释放程度、 有效燃烧热和烟释放过程, 阻燃性能提高。      

Preparation and properties of fluorine-containing colorless polyimide nanocomposite films with organo-modified montmorillonites for potential flexible substrate

We prepared transparent polyimide (PI) and organo-modified montmorillonite (OMMT) nanocomposite films from the solution of poly(amic acid) and various amounts (0.5-2 wt%) of OMMT in N,N-dimethylacetamide (DMAc). The Poly(amic acid) was prepared from the reaction of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 2,2'-bis (trifluoromethyl)-4,4'-diamino phenyl (TFDB). Dodecylamine (C12-) and dodecyltriphenylphosphonium chloride (C12PPh-Cl-) were used as organic modifiers in OMMT. The PI/OMMT nanocomposite films were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscope (TEM), UV-Vis transmission spectra, thermomechanical analysis (TMA), and rheometric dynamic analysis (RDA). As the OMMT contents is increased, PI/OMMT nanocomposites generally show better properties compared to pristine PI films, although the transparency of the PI/OMMT nanocomposite films is sacrificed slightly. However, it is concluded that these nanocomposite films are good candidates for potential flexible substrates.     

Effects of organo-modified montmorillonite on the tribology performance of bismaleimide-based nanocomposites

Poly(allyl condensed polynuclear aromatic-bismaleimide) (ACOPNA–BMI) with different loadings of an organo-modified montmorillonite (OMMT) nanocomposites were successfully prepared via in situ suspension polymerization. Exfoliation/intercalation phenomena were detected using transmission electron microscopy (TEM) and X-ray diffraction (XRD). Positive effects of the exfoliated platelets on the wearable and thermal behaviours were achieved by varying the OMMT load. The lowest friction coefficient of ACOPNA–BMI/2.0 wt.% OMMT was 0.46 at a wear rate of 0.508 × 10^− 6 mm³/Nm, which was superior to that of pure ACOPNA–BMI copolymer resin. The thermostabilities of the materials were assessed by thermogravimetric analysis (TGA). The temperature at the maximum rate of thermal decomposition of ACOPNA–BMI/3 wt.% OMMT was 480 °C, which was much higher than that of the pure ACOPNA–BMI copolymer (436 °C). The nanocomposite obtained, which is a suitable wearable material, can be widely used for protecting drilling tools in petroleum engineering applications due to its thermostability and good self-lubrication properties.     

双辊共混法制备EPDM/OMMT纳米复合材料

自制一种有机改性蒙脱土(OMMT),采用双辊共混法与三元乙丙橡胶复合,得到了具有高强度、低硬度等超常力学性能的乙丙橡胶/有机蒙脱土纳米复合材料。透射电镜观察表明,制备出了半剥离型纳米复合材料,力学性能测试显示,在低填充量(15份以下)时,纳米复合材料的各项力学性能远超过同含量下高耐磨碳黑体系的。在填充量为10份时,有机土填充体系的断裂强度为15.85 MPa,是碳黑填充体系(6.57 MPa)的2.4倍,是纯橡胶体系(2.05 MPa)的7倍多;撕裂强度也高于碳黑体系和纯胶体系的;而此时纳米复合材料的邵A硬度仅为58.5,比相同强度下碳黑补强体系的低近10。     

Polylactide based nanostructured biomaterials and their applications

Polylactide (PLA) is one of the most innovative materials being actively investigated for a wide range of industrial applications. The polymer is a linear aliphatic thermoplastic polyester which is biodegradable as well as biocompatible, which makes it highly versatile and attractive to various commodities and medical applications. A large variety of nanoparticles of different nature and size can be blended with PLA, therefore, generating a new class of nanostructured biomaterials or nanocomposites with interesting physical properties and applications. PLA based nanostructured biomaterials are the focus of this review article, throwing light on their preparation techniques, physical properties, and industrial applications. Structural characteristics and morphological features of PLA based nanocomposites have been explained on the basis of X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Depending upon the nature and characteristics of the nanoparticles, the ultimate properties of the resulting nanocomposite materials can be tailored. Biocompatible materials such as carbon nanotubes, cellulose nanowhiskers, hydroxyapitite, etc. could be incorporated into the PLA matrix, which increase the potential of PLA for biomedical applications. Applications of PLA based nanostructured materials in different areas have been summarized.     

Green synthesis of nanosilver‐decorated graphene oxide sheets

A green facile method has been successfully used for the synthesis of graphene oxide sheets decorated with silver nanoparticles (rGO/AgNPs), employing graphite oxide as a precursor of graphene oxide (GO), AgNO₃ as a precursor of Ag nanoparticles (AgNPs), and geranium (Pelargonium graveolens) extract as reducing agent. Synthesis was accomplished using the weight ratios 1:1 and 1:3 GO/Ag, respectively. The synthesised nanocomposites were characterised by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X‐ray diffraction, UV‐visible spectroscopy, Raman spectroscopy, energy dispersive X‐ray spectroscopy and thermogravimetric analysis. The results show a more uniform and homogeneous distribution of AgNPs on the surface of the GO sheets with the weight ratio 1:1 in comparison with the ratio 1:3. This eco‐friendly method provides a rGO/AgNPs nanocomposite with promising applications, such as surface enhanced Raman scattering, catalysis, biomedical material and antibacterial agent.Inspec keywords: silver, nanoparticles, graphene, nanocomposites, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X‐ray diffraction, ultraviolet spectra, visible spectra, X‐ray chemical analysis, surface enhanced Raman scattering, catalysis, nanofabricationOther keywords: antibacterial agent, biomedical material, catalysis, surface enhanced Raman scattering, rGO‐AgNP nanocomposite, eco‐friendly method, homogeneous distribution, thermogravimetric analysis, energy dispersive X‐ray spectroscopy, Raman spectroscopy, UV‐visible spectroscopy, X‐ray diffraction, atomic force microscopy, transmission electron microscopy, scanning electron microscopy, nanocomposites, reducing agent, geranium, graphene oxide sheets, graphite oxide, silver nanoparticles, green facile method     

Characterizations of WC–10Co nanocomposite powders and subsequently sinterhip sintered cemented carbide

Ultrafine WC–Co cemented carbides, combining high hardness and high toughness, are expected to find broad applications. In this study, WC–10Co–0.4VC–0.4Cr₃C₂ (wt.%) nanocomposite powders, whose average grain size was about 30 nm, were fabricated by spray pyrolysis-continuous reduction and carbonization technology. The as-prepared nanocomposite powders were characterized and analyzed by chemical methods, scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET analysis and atomic force microscopy (AFM). Furthermore, “sinterhip” was used in the sintering process, by which ultrafine WC–10Co cemented carbides with an average grain size of 240 nm were prepared. The material exhibited high Rockwell A hardness of HRA 92.8, Vickers hardness HV₁ 1918, and transverse rapture strength (TRS) of 3780 MPa. The homogeneously dispersed grain growth inhibitors such as VC, Cr₃C₂ in nanocomposite powder and the special nonmetal–metal nanocomposite structure of WC–10Co nanocomposite powder played very important roles in obtaining ultrafine WC–10Co cemented carbide with the desired properties and microstructure. There was an abundance of triple junctions in the ultrafine WC–10Co cemented carbide; these triple junctions endowed the sintered specimen with high mechanical properties.     

Biodegradable poly(propylene carbonate)/montmorillonite nanocomposites prepared by direct melt intercalation

Intercalation-exfoliated nanocomposites derived from poly(propylene carbonate) (PPC) and organo-modified montmorillonite (OMMT) were prepared by direct melt blending in an internal mixer. The nano-scale dispersion of the OMMT layers within the PPC matrix was verified using wide angle X-ray scattering and transmission electron microscopy technologies. Static mechanical properties were determined by using a tensile tester. The PPC/OMMT nanocomposites with lower OMMT content showed an increase in thermal decomposition temperature when compared with both pure PPC and the composites prepared from un-modified MMT. Dynamic mechanical analysis indicated that nano-scale OMMT dispersed well within PPC matrix and therefore enhanced the storage modulus of the composites.     

Preparation and endothelialization of decellularised vascular scaffold for tissue-engineered blood vessel

The proliferation of cells on the decellularised tissues fixed by chemical crosslinking agent is retarded for cytotoxicity of crosslinked tissues. To overcome this disadvantage, we prepared the decellularised vascular scaffold through fixing the porcine thoracic arteries with 40mL/L ethylene glycol diglycidyl ether (EGDE), and reduced the cytotoxicity of this scaffold by treating it with lysine and coating it with type I collagen, finally endothelialized it in vitro. The EGDE-fixed porcine thoracic arteries were examined morphologically. The fixation index determination and the biomechanics test were also performed. Human umbilical vein endothelial cells (HUVECs) were seeded on the type I collagen-coated surface of different modified vascular tissues (fixed with glutaraldehyde or EGDE or EGDE + lysine), and the growths of HUVECs on the specimens were demonstrated by means of MTT test. Finally, HUVECs were seeded on the luminal surface of the modified porcine vascular scaffolds which were respectively treated in the same manner described above, and then cultured for 7 days. On the seventh day, the HUVECs on the specimens were examined by means of light microscopy, scanning electron microscopy and transmission electron microscopy (TEM). The antigenicity of the vascular tissues can be diminished by EGDE through getting rid of cell in the vascular tissues or reducing the level of free amino groups in the vascular tissues. In this study, it was also found that the EGDE-fixed porcine vascular tissues appeared similar to the native porcine vascular tissues in color and mechanical properties. After treated by 2% lysine and coated with type I collagen, the EGDE-fixed porcine vascular tissues were characterized by low cytotoxicity and good cytocompatible. The HUVECs can proliferate well on the modified vascular tissues, and easily make it endothelialized. The results showed that the modified porcine vascular scaffolds should be a promising material for fabricating scaffold of tissue-engineered blood vessel.     

原位插层聚合尼龙6/超分散有机蒙脱土剥离型纳米复合材料的结构和性能

采用原位插层聚合法制备了尼龙6/蒙脱土剥离型纳米复合材料,讨论了超分散有机蒙脱土的用量对复合材料性能的影响,用动态力学分析(DMA)、X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)等手段研究了纳米复合材料的结构和性能。结果表明,有机蒙脱土加入量为3%(质量分数,下同)时,复合材料综合性能最佳;有机蒙脱土的加入大大提高了尼龙6的综合性能,并提高了尼龙6的储能模量和玻璃化温度。有机蒙脱土在尼龙6基体中有良好的分散性和相容性,蒙脱土片层被完全剥离,在尼龙6基体中实现了纳米级分散。     

有机硅丙烯酸酯/蒙脱土纳米复合乳液的制备及表征

以十二烷基苯磺酸(DBSA)为插层剂改性蒙脱土(MMT),制得了有机蒙脱土(OMMT)。采用原位插层聚合法,以OMMT、八甲基环四硅氧烷、乙烯基三甲氧基硅烷以及甲基丙烯酸酯甲酯、丙烯酸丁酯和丙烯酸为原料,制备了有机硅丙烯酸酯/蒙脱土纳米复合乳液。考察了OMMT用量对乳胶粒径及乳胶膜性能的影响,并对OMMT及乳胶膜的结构进行了表征。结果表明:当OMMT的用量为2.0%时,乳胶粒子尺寸为纳米级,乳胶膜的耐热性以及各项物理机械性能均得到明显改善。XRD分析表明,MMT变为OMMT后,其层间距从1.23nm增大至1.54nm。FT-IR分析表明,有机硅和丙烯酸酯单体在OMMT层间发生接枝聚合反应。     

Stem cell response to multiwalled carbon nanotube-incorporated regenerated silk fibroin films

Multiwalled carbon nanotubes (MWCNTs) are considered to be the ideal reinforcements for biorelated applications on account of their remarkable structural, mechanical and thermal properties. However, before MWCNTs can be incorporated into new and existing biomedical devices, their toxicity and biocompatibility need to be investigated thoroughly. In this study, regenerated silk fibroin/MWCNT nanocomposite films were prepared using a solvent system with pre-dispersed MWCNTs. Their biocompatibility was examined in vitro using human bone marrow stem cells. Scanning electron microscopy and a WST-1 assay demonstrated that the silk fibroin/MWCN film supported BMSC attachment and growth over 7 days in culture similar to the silk fibroin only film.