纳米碳酸钙粒子在硅酮密封胶中的增强作用

纳米复合材料以其优异的性能已引起人们的广泛兴趣 [1～ 4 ] .硅酮胶广泛应用于建筑玻璃件的粘接 .粘接的强度取决于胶的化学组分、配方、增强剂的种类和用量等 .碳酸钙纳米粒子以其独有的特性被用作硅酮胶的增强剂 ,极大提高了胶的拉伸强度、模量和硬度 .深入研究纳米碳酸钙粒子的增强机理与基体的界面作用 ,对于进一步提高硅酮胶的性能 ,从分子和界面的角度设计硅酮胶的结构具有重要的理论和实际意义 [5,6 ] .本文选用不同粒径的 3种活性纳米碳酸钙 ,研究粒径大小和用量对硅酮胶力学性能和分子运动的影响 ,探索纳米碳酸钙粒子的增强作用机…     

金核银壳纳米粒子薄膜的制备及SERS活性研究

采用柠檬酸化学还原法制备金溶胶, 通过自组装技术在石英片表面制备金纳米粒子薄膜, 在银增强剂混合溶液中反应获得金核银壳纳米粒子薄膜. 用紫外-可见吸收光谱仪和原子力显微镜(AFM)研究了不同条件下制备的金核银壳纳米粒子薄膜的光谱特性和表面形貌, 并以结晶紫为探针分子测量了金核银壳纳米粒子薄膜的表面增强拉曼光谱(SERS). 结果表明, 金纳米粒子薄膜的分布、银增强剂反应时间的长短对金核银壳纳米粒子薄膜的形成均有重要影响. 制备过程中, 可以通过控制反应条件获得一定粒径的、具有良好表面增强拉曼散射活性的金核银壳纳米粒子薄膜.     

多功能纳米材料在肿瘤放疗增敏中的应用

放射治疗是利用放射线治疗肿瘤的一种局部治疗方法,目前已成为临床上最常用、最有效的恶性肿瘤治疗手段之一。但放射治疗仍存在辐射剂量高、对健康组织副作用大,特别是肿瘤细胞放射抵抗性强等缺点。随着纳米医学的发展,多功能纳米放疗增敏剂为增强肿瘤细胞放射敏感性、提高放疗效果提供了新机遇。本文结合纳米材料在放疗增敏中的优势和潜能,概括了纳米放疗增敏剂的主要类型和目前已进入临床实验的一些实例,简述了多功能纳米放疗增敏剂在肿瘤放射治疗中的应用,并归纳了纳米材料增敏放疗的主要途径和影响因素。最后总结和展望了多功能纳米放疗增敏剂面临的挑战和发展前景。     

纳米二氧化钛增强聚丙烯酰胺/聚乙烯亚胺凝胶的制备及其性能

聚乙烯亚胺（PEI）是一种环境友好型交联剂，但与聚丙烯酰胺(PAM)形成的凝胶体系强度较弱，而纳米二氧化钛是一种非常有效的结构增强剂。制备了纳米二氧化钛增强的PAM/PEI凝胶，其结构经XRD和TG表征。结果表明：纳米二氧化钛对PAM/PEI凝胶有良好的增强作用。在90 ℃下，可使凝胶的成胶时间从7 h缩短至3 h，凝胶强度由F提高至H。     

pH敏感纳米凝胶的制备及其在siRNA转染中的应用

通过分散聚合的方法,以改性了双键的葡聚糖(Dex-AA)作为交联剂,甲基丙烯酸二甲氨基乙酯(DMAEMA)作为单体,过硫酸铵(APS)和四甲基乙二胺(TEMED)分别作为引发剂和助引发剂,合成了不同交联度的、具有pH敏感内吞增强作用的葡聚糖纳米凝胶(DD-NGs),并测试了其复合siRNA进行转染的能力.实验结果表明,该纳米凝胶表面带有正电荷,具有较好的担载siRNA进入肿瘤细胞并沉默基因的能力,且具有pH响应粒径变化的性质.在pH=7.4的体液环境中,纳米凝胶与基因的复合物粒子较小;在肿瘤酸性(pH=6.8)条件下,纳米凝胶与基因的复合物粒子变大,显著地增强了肿瘤细胞对纳米凝胶与基因复合物的内吞.     

纳米纤维素研究及应用进展Ⅱ

纳米纤维素是一种新型的高分子功能材料,具有独特的结构和优良的性能,特别是细菌纤维素,其三维纳米网状结构,生物适应性,良好的机械稳定性,抗菌性等优良性能使它越来越收到重视。本文是"纳米纤维素研究及应用进展Ⅰ"的下篇,本文中介绍了近年来对于纳米纤维素应用和研究的进展。文中主要内容有纳米纤维素在生物、医学、增强剂、造纸工业、净化、传导、与无机物复合、食品工业、磁性复合物等方面的应用。     

手性化合物组合修饰剂对CdSe纳米晶荧光性能的影响及标记大肠杆菌的研究

以手性化合物L-青霉胺、D-青霉胺、L-半胱氨酸为单一修饰剂或组合成双修饰剂,合成不同修饰剂修饰的CdSe纳米晶。对最佳合成条件如配料比,反应pH值,回流温度,回流时间进行了优化,对CdSe纳米晶发光强度及稳定性进行了系统研究。结果发现双修饰剂修饰的纳米晶比单修饰剂修饰的纳米晶荧光强度高,稳定性好;双修饰剂中第二修饰剂的空间位阻小的修饰效果好;不同手性修饰剂之间能以稳定方式结合的修饰效果好。研究了CdSe纳米晶对生物大分子的识别,仅发现核酸对CdSe纳米晶有明显的作用,用CdSe纳米晶作为荧光探针对大肠杆菌进行标记。     

纳米压印抗蚀剂研究进展

纳米压印是最有希望的下一代纳米成像技术之一.基于其机械压印原理,纳米压印技术可以实现的图形分辨率超越了在别的传统技术中由光衍射或粒子束散射造成的局限.本文介绍纳米压印技术的基本原理,回顾了近期纳米压印抗蚀剂的研究进展.对影响抗蚀剂性能的主要因素进行讨论,包括玻璃化转化温度/热稳定性、粘度/平均分子量、抗蚀性能等.分别介绍了热压印和紫外压印的常见抗蚀剂材料,这些抗蚀剂的主要部分包括聚甲基丙烯酸甲酯(PM-MA)、有机硅改性的聚(甲基)丙烯酸酯、聚酰胺酯、聚二甲基硅烷、聚乙烯基醚化合物、环氧树脂等,并给出这些抗蚀剂体系的优、缺点.本文还介绍了纳米压印抗蚀剂面临的主要问题,对纳米压印技术的优势和问题作了小结.     

表面增强拉曼光谱法快速检测纺织品中的偶氮染料

建立纺织品中偶氮染料的表面增强拉曼光谱快速筛查方法。以24种芳香胺为研究对象,利用表面增强拉曼光谱技术,结合使用金纳米粒子增强剂,对纺织品中的偶氮染料进行检测。通过对样品纳米金溶胶的用量、缓冲溶液种类和pH值的优化,确定了最佳优化条件:纳米金溶胶的用量为50μL,缓冲溶液为柠檬酸溶液,pH值为6.0。同时对24种芳香胺的特征峰进行采集、分析和分类,确定分为以下几类:苯胺类、联苯类、含硝基类、萘类。该方法操作简单,易于掌握,可以快速筛选出纺织品中的偶氮染料。     

纳米SiO_2/聚丙烯复合材料的反应性增容

利用反应性增容技术制备了纳米二氧化硅/聚丙烯复合材料.首先探讨了将甲基丙烯酸缩水甘油酯-丙烯酸丁酯共聚物接枝到纳米二氧化硅粒子表面进行改性的各种影响因素,然后将接枝改性纳米二氧化硅与聚丙烯以及作为反应性增容剂的氨基化聚丙烯共混.结果表明,改性粒子上的环氧基与氨基化聚丙烯上的氨基之间的化学反应大大增强了复合材料的界面作用,从而在粒子含量很低时明显提高了聚丙烯的拉伸强度、模量和冲击强度.     

Preparation and properties of POSS grafted polypropylene by reactive blending

The octavinyl polyhedral oligomeric silsesquioxane (POSS) grafted polypropylene (PP) was first prepared by reactive blending. The structure and properties of physical blending and reactive blending composites of PP/POSS were investigated by wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA). WAXD analysis shows that the POSS in the reactive blending composites has better compatibility with PP than in the physical blending composites. The β-form crystalline hence disappears even the non-reactive POSS can act as an effective β-nucleating agents. DSC analysis shows the reactive blending composites have higher crystalline temperature while POSS in the physical blending composites have little effect on the crystalline temperature. The modulus of reactive blending composites increases in the presence of POSS, while that of the physical blending composites decreases with increasing POSS content.     

PDMS mixed-matrix membranes with molecular fillers via reactive incorporation and their application for bio-butanol recovery from aqueous solution

Mixed-matrix membrane (MMM) consisting of fillers in polymeric matrix offers a promising approach to develop high-performance membranes, while remain challenges in achieving ideal filler dispersion and interfacial morphology. Herein, we reported on a new kind of MMM with molecular-level dispersion of filler via a proposed reactive incorporation approach. Specifically, polyhedral oligomeric silsesquioxanes (POSS) with vinyl groups was grafted with ethoxy groups to build covalent bond with hydroxyl-terminated polydimethylsiloxane (PDMS) chains to fabricate PDMS MMMs uniformly dispersed with POSS molecules. The molecular dispersion of POSS in PDMS matrix was visualized by SEM, AFM, and TEM characterizations, as well as reflected by XRD analysis. The PDMS chain conformation affected by the reactive incorporation of POSS was investigated by analyzing the thermal and mechanical properties of the POSS/PDMS MMMs using DSC, TGA, and DMA measurements. Contact angle test was used to study the surface affinity and positron annihilation technique was employed to probe the free volumes, which are respectively associated with the sorption and diffusion behavior in the POSS/PDMS MMMs. The results demonstrated that molecular cages and crosslinking effect of POSS led to an increase of large free volumes while a decline of small free volumes. Therefore, the PDMS MMM with reactive incorporation of only 2 wt.% POSS simultaneously enhanced the butanol permeability (by 78%) and butanol/water selectivity (by 124%) for pristine PDMS membrane, transcending the performance limit of state-of-the-arts organophilic membranes. The proposed reactive incorporation approach may provide a platform of developing highly efficient membranes for molecular separation.     

Rheological behavior of polypropylene/octavinyl polyhedral oligomeric silsesquioxane composites

The reactive blending composites of isotactic polypropylene (PP)/octavinyl polyhedral oligomeric silsesquioxane (POSS) were prepared in the presence of dicumyl peroxide. Comparison of the rheological behavior of physical and reactive blending composites was made by oscillatory rheological measurements. It was found that the viscosity of physical blending composites drops at lower POSS content (0.5–1 wt %) and thereafter increases with increasing POSS content; that of reactive blending composites increases with increasing POSS content and displays a solid‐like rheological behavior at low frequency region when POSS content is higher than 1 wt %. The deviation of reactive blending composites from the scaling log G′–log G″ of linear polymer in Han plot, upturning at high viscosity in Cole–Cole plot, and from van Gurp–Palmen plot are related to the gelation behavior reactively. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 526–533, 2008     

Synthesis and properties of low‐dielectric‐constant polyimides with introduced reactive fluorine polyhedral oligomeric silsesquioxanes

A high‐performance, low‐dielectric‐constant polyimide (PI) nanocomposite from poly(amic acid) (PAA) cured with a reactive fluorine polyhedral oligomeric silsesquioxane (POSS) isomer was successfully synthesized. The features of this reactive fluorine POSS isomer [octakis(dimethylsiloxyhexafluoropropylglycidyl ether)silsesquioxane (OFG)] provided two important approaches (containing fluorine or being porous in the polymer matrix) of reducing the dielectric constant of PI. This reactive POSS isomer had an average of four epoxy groups and four fluorine groups on the POSS cage, and the epoxy groups could be cured with PAA to form a network framework of a PI/POSS nanocomposite. The PI/OFG nanocomposite had a high crosslinking density, high porosity (24.3%), high hydrophobicity, and low polarizability. These properties enhanced the thermal (glass‐transition temperature ～ 362 °C) and dielectric (dielectric constant ～2.30) properties of PI more than other POSS derivatives introduced into the PI backbone. A large number of small POSS particles (<10 nm) were embedded inside the PI matrix when the OFG content was low, whereas interconnected POSS aggregation domains were observed when the OFG content was high. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5391–5402, 2006     

用于聚合物纳米复合材料的化学改性POSS

综述了多面齐聚倍半硅氧烷(POSS)与聚合物的相容性、用于使POSS化学改性的有机反应以及改性POSS作为聚合物纳米复合材料的添加型及反应型纳米填料的实例.     

Isothermal crystallization kinetics of polypropylene/POSS composites

Polypropylene (PP)/octavinyl polyhedral oligomeric silsesquioxane (POSS) composites were prepared by two different processing methods: reactive blending and physical blending, and the crystallization behavior of PP and PP/POSS composites was studied by means of differential scanning calorimetry and polarized optical microscope. The results showed that the crystallization of PP in PP/POSS composites was strongly influenced by the different processing methods. POSS particles can act as effective nucleating agent, accelerating the crystallization of PP. The crystallization rate increased more dramatically for the reactive blending composite due to the stronger nucleating effect of PP grafted POSS. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1762–1772, 2008     

Novel hybrid systems based on poly(propylene-g-maleic anhydride) and Ti-POSS by direct reactive blending

Novel hybrid systems based on maleic anhydride-grafted polypropylene (PPgMA) and home-made Ti-containing amino polyhedral oligomeric silsesquioxanes (Ti-POSS-NH₂) have been prepared by one-step reactive blending, and their properties have been compared with those of systems based on a non-reactive POSS (POSS). The occurrence of a reaction between PPgMA and the reactive POSS molecules has been assessed by Fourier Transform Infrared Resonance (FTIR) measurements, whereas dispersion of POSS into the polymer was evaluated by Scanning Electron Microscopy (SEM), showing a nanometric dispersion only for the reactive POSS. Thermo-oxidative behaviour was studied by Thermogravimetric Analysis (TGA), showing a delayed volatilization of the PPgMA/Ti-POSS-NH₂ with respect to both PPgMA/POSS and pristine PPgMA, which is attributed to the chemical activity of Ti in Ti-POSS-NH₂. To highlight the mechanism of the hybrid system decomposition, samples which underwent a thermal treatment at 250 °C, i.e. the onset temperature for polymer matrix decomposition in thermo-oxidative conditions, have been studied by FTIR and X-Ray Photoelectron Spectroscopy (XPS) measurements.     

Bridged polyhedral oligomeric silsesquioxane (POSS): A potential member of silsequioxanes

Two novel and well-defined polyhedral oligomeric silsesquioxanes（POSS） with two same Si₈O₁₂ cores and a reactive NH group, namely bridged-POSS（2a and 2b）,have been prepared by the traditional ’corner-capping’ reaction.X-ray diffraction demonstrates that those two POSS have the similar T₈ structure.From the thermo-gravimetric analysis,bridged-POSS shows the belter thermal degradation stability than the contrastive POSS.     

Nanocomposites based on polyamidoimide and octahedral silsesquioxanes

New polymeric nanocomposites were prepared by covalent bonding of nanosized octahedral silsesquioxane particles containing reactive glycidyl group to polyamidoimides containing a carboxy group in the pendant chain. The influence of temperature, molecular weight of the polymer, and reaction time on the covalent bonding of polyhedral oligomeric silsesquioxane (POSS) nanoparticles was revealed. The effect of the POSS nanoparticle incorporation on the structure, dielectric and deformation-strength properties, and heat resistance of the new polymeric nanocomposites was examined.     

Synthesis and characterization of an isocyanate functionalized polyhedral oligosilsesquioxane and the subsequent formation of an organic-inorganic hybrid polyurethane

Organic-inorganic hybrids are an important class of new materials that offer improved thermal and mechanical properties over normal polymers. They may be produced by either the sol-gel route or through the use of inorganic compounds possessing reactive functional groups. Polyhedral oligosilsesquioxanes (POSS) are completely defined molecules of nanoscale dimensions that may be functionalized with reactive groups suitable for the synthesis of new organic-inorganic hybrids. Here we report the synthesis and characterization of a novel POSS possessing eight isocyanate groups via the hydrosilylation of octakis(hydridodimethylsiloxy)octasilsesquioxane (Q8M8H) and m-isopropenyl-alpha,alpha'-dimethylbenzyl isocyanate (m-TMI). The suitability of this new macromer to the synthesis of a organic-hybrids has been explored by forming a new type of highly cross-linked polyurethane elastomer via reaction of the macromer with poly(ethylene glycol) using dibutyltin dilaurate catalyst.