PVP改性氧化硅溶胶的微结构和流变性

以正硅酸乙酯为前驱体,聚乙烯吡咯烷酮（PVP）为聚合物改性添加剂,在碱性条件下制备氧化硅溶胶,通过小角X射线散射测量了改性溶胶的微结构参数,辅以动态光散射观测溶胶颗粒生长,研究了聚合物量、碱催化剂量和水量对溶胶颗粒度、分形特征以及流变性的影响规律.由于PVP链中强极性的分子内酰胺基团和氧化硅颗粒表面的羟基形成氢键,致使溶胶颗粒被聚合物链包裹,严重阻碍了溶胶颗粒的生长,使凝胶时间延长,流变性发生变化,同时对溶胶颗粒的微结构产生影响.     

疏水性对溶胶-凝胶SiO2薄膜抗真空污染及抗激光损伤能力的影响

以正硅酸乙酯作为前驱体,利用碱催化方式制备了SiO2溶胶,通过在溶胶中添加含疏水基团(-CH3)的六甲基二硅氮烷(HMDS)对溶胶进行改性,使用添加不同物质的量比HMDS改性后的溶胶用提拉法在K9基片上镀膜,获得了具有疏水性能的SiO2薄膜。采用自制接触角测量仪、紫外-可见-近红外分光光度计研究了薄膜的水接触角和透过率。测试了薄膜的激光损伤阈值,并观察了激光辐照后薄膜的损伤形貌。通过真空污染实验对薄膜的抗污染能力及抗激光损伤能力进行了研究。实验结果表明:经疏水改性的溶胶所镀制的薄膜激光损伤阈值由未改性样品的24.3 J·cm-2增加到37 J·cm-2(1 064 nm,10 ns),且抗真空污染能力大大加强:在真空环境下保存168 h后,未改性样品的峰值透过率下降了2%,而疏水改性后的样品峰值透过率仅下降了0.25%,并保持了较高的激光损伤阈值(30.8 J·cm-2)。     

微结构与表面修饰对二氧化硅多孔薄膜疏水性能的影响

通过引入聚乙二醇(PEG)改性传统二氧化硅(SiO2)溶胶,得到了粒径分布较宽且粒径可控的溶胶。比较了六甲基二硅氮烷(HMDS)溶胶内修饰和薄膜表面修饰以及溶胶粒径对SiO2薄膜疏水性能的影响。采用动态光散射粒度仪定量测试了二氧化硅溶胶老化过程中粒度的变化,用原子力显微镜、接触角测试仪、红外光谱仪、紫外-可见-近红外分光光度计分别对薄膜的表面形貌、表观静态接触角、薄膜成分及透光率等进行了测量。结果表明:PEG的添加可有效增大溶胶粒度从而增大薄膜的粗糙度,提高薄膜的疏水性。表面修饰效果受修饰方式和SiO2粒径影响,粒径较小时有利于溶胶内修饰,粒径较大时有利于对薄膜修饰。经过表面修饰剂(HMDS)的气氛处理得到了接触角为152°的超疏水薄膜,而且相比溶胶内修饰可以减小薄膜透光率的损失。     

疏水性对溶胶-凝胶SiO2薄膜抗真空污染及抗激光损伤能力的影响

以正硅酸乙酯作为前驱体, 利用碱催化方式制备了SiO₂溶胶, 通过在溶胶中添加含疏水基团(-CH₃)的六甲基二硅氮烷(HMDS)对溶胶进行改性, 使用添加不同物质的量比HMDS改性后的溶胶用提拉法在K9基片上镀膜, 获得了具有疏水性能的SiO₂薄膜。采用自制接触角测量仪、紫外-可见-近红外分光光度计研究了薄膜的水接触角和透过率。测试了薄膜的激光损伤阈值, 并观察了激光辐照后薄膜的损伤形貌。通过真空污染实验对薄膜的抗污染能力及抗激光损伤能力进行了研究。实验结果表明:经疏水改性的溶胶所镀制的薄膜激光损伤阈值由未改性样品的24.3 J·cm^-2增加到37 J·cm^-2(1 064 nm, 10 ns), 且抗真空污染能力大大加强:在真空环境下保存168 h后, 未改性样品的峰值透过率下降了2%, 而疏水改性后的样品峰值透过率仅下降了0.25%, 并保持了较高的激光损伤阈值(30.8 J·cm^-2)。     

二氧化钛/聚乙烯吡咯烷酮纳米复合薄膜的制备与表征

采用溶胶-凝胶法(so1 gel)制备了TiO2/聚乙烯吡咯烷酮(PVP)有机 无机纳米复合薄膜.采用扫描电子显微镜、接触角测定仪、红外光谱仪、紫外 可见吸收光谱仪和静 动摩擦系数测定仪对所制备的TiO2/PVP纳米复合薄膜进行了结构表征和性能研究.结果表明:所制备的TiO2/PVP纳米复合薄膜表面平整光滑、无裂纹、具有一定的疏水性、良好的透明性、防紫外线性能和减摩抗磨性能.     

纳米二氧化硅的表面改性研究

以γ-缩水甘油醚丙基三甲氧基硅烷(GPTMS)对酸催化水解正硅酸乙酯(TEOS)聚合得到的纳米二氧化硅胶粒表面进行接枝改性,用激光粒径仪测定二氧化硅颗粒的粒径,并用透射电子显微镜(TEM)观察了改性前后二氧化硅胶粒的分散状况,采用傅立叶红外(FTIR)光谱法对改性前后的二氧化硅粉体进行了分析,通过热失重分析(TGA)法对GPTMS接枝改性二氧化硅胶粒表面的接枝度进行分析计算,同时对颗粒溶胶的ζ电位进行了测试,结果表明:改性后二氧化硅胶粒分散性大大提高,硅烷偶联剂浓度对接枝度有显著影响,当GPTMS的浓度为1mL/S iO2(g)时,接枝度达到最大,且颗粒表面的物理化学性能发生显著变化。     

基体表面性质对原位聚合沉积导电聚苯胺薄膜性能的影响

以水溶性高分子聚乙烯吡咯烷酮(PVP)为空间稳定剂,在经十八烷基三氯硅烷(OTS)改性的玻璃表面进行原位聚合,沉积得到导电聚苯胺(PANI)薄膜。采用表面界面张力仪、扫描电镜(SEM)、紫外可见光谱(UV-Vis)、红外光谱(FT-IR)、四探针电导率测试仪及光学显微镜对不同基体表面的接触角、PANI膜的形貌、厚度、结构、导电性及其在亲/憎水表面选择性沉积性能进行测定。结果表明:OTS对玻璃表面的改性促进了聚苯胺的沉积且提高了薄膜厚度,薄膜饱和厚度达到200 nm;缩短了溶液中苯胺分散聚合的诱导期,反应速率增大;与未改性玻璃表面沉积的薄膜相比,改性的玻璃表面得到的聚苯胺薄膜更加细密均匀,聚苯胺颗粒尺寸小,堆积紧密;薄膜的电导率达到7.5×10-3S/cm;OTS改性对基体表面的薄膜生长和溶液中的苯胺聚合具有催化作用。     

热辅助存储磁盘硅掺杂非晶碳薄膜氧化的ReaxFF反应力场分子动力学模拟（英文）

热辅助磁存储技术是一种提高磁盘存储面密度到1 Tb·in~(-2)的方法,在数据写入过程中的激光局部加热会使磁盘非晶碳薄膜氧化。本文采用Reax FF反应力场分子动力学方法,建立硅掺杂非晶碳(a-C:Si)薄膜在激光诱导氧化的模型,从原子尺度分析a-C:Si薄膜的结构变化、氧化过程,确定了氧化机理以及激光加热次数对氧化的影响规律。a-C:Si薄膜的氧化发生在加热阶段和初始降温阶段,在加热过程中a-C:Si薄膜的体积扩张和降温过程中原子应变引起碳原子团簇,均使薄膜中sp~2碳含量增加。随着加热次数的增加,表面未饱和原子数量减少和氧原子低扩散率使薄膜氧化速率逐渐降低。此外,非晶薄膜的表面缺陷使分子氧成为氧化剂,表面原子剪切应变使Si―O―O―Si链中O―O键断裂,重构氧化表面,进而促进a-C:Si薄膜的氧化。     

TeO2-SiO2/α-TeO2复合薄膜的电化学-溶胶凝胶制备及非线性光学性能

以异丙醇碲和正硅酸乙酯作为前驱体,配制了稳定的TeO2-SiO2复合溶胶;以之为电解液采用电化学-溶胶凝胶法制备了黑色的凝胶薄膜,将薄膜经热处理后得到灰白色半透明的复合薄膜.分别采用XRD和SEM-EDX研究复合薄膜的晶体结构、表面形貌及其组成,结果表明凝胶薄膜的主要成分为Si,Te,O元素,黑色的凝胶薄膜为TeO2-SiO2/Te,灰白色半透明的复合薄膜为少量Te的SiO2-TeO2/α-TeO2;α-TeO2颗粒和少量Te颗粒均匀分散在TeO2-SiO2凝胶复合薄膜中.采用Z-scan方法测试薄膜的光学性能,结果表明其三阶非线性极化率χ(3)为2.171×10-14(m V-1)2.     

疏水性有序介孔氧化硅薄膜的制备

采用溶胶−凝胶技术并结合蒸发诱导自组装工艺, 以三嵌段共聚物EO₂₀PO₇₀EO₂₀ (P123)为模板剂, 使用浸渍提拉法制备了有序介孔氧化硅薄膜, 并使用不同的表面修饰剂对薄膜进行表面处理, 制备了疏水性有序介孔氧化硅薄膜. 利用FT-IR、小角XRD、HRTEM分别表征薄膜的化学物种和孔结构, 探讨了热处理温度和老化时间对薄膜介孔结构的影响, 通过接触角测试研究薄膜的疏水性能, 考察了修饰剂种类、修饰浓度和修饰时间对薄膜疏水性的影响, 结果表明所制备的薄膜为高度有序的介孔氧化硅薄膜, 孔径大小约为8 nm|表面修饰对薄膜的有序性有一定影响, 经三甲基氯硅烷(TMCS)和g-氨丙基三乙氧基硅烷(KH-550)修饰后的薄膜具有很好的疏水性能, 接触角分别为112°和96°|修饰后薄膜的水汽稳定性良好, 仍能保持有序介孔结构, 孔径达7.5 nm, 接触角达93°.     

紫铜表面3-巯丙基三乙氧基硅烷薄膜的制备与耐蚀性能

利用傅里叶变换红外(FTIR)光谱分析了3-巯丙基三乙氧基硅烷分别在酸性和碱性的醇-水溶液中水解后以及在紫铜表面成膜后的结构特征. 利用极化曲线、电化学阻抗谱(EIS)和盐水浸泡实验测试了硅烷膜的耐腐蚀性能. 结果表明: 3-巯丙基三乙氧基硅烷在酸性溶液中能够发生一定程度的水解并生成Si―OH结构, 且当该溶液在自然状态下晾干后, 其水解程度进一步增大. 在碱性溶液中该硅烷只发生少量的水解, 溶液中含有较多SiOCH₂CH₃结构, 且在溶液自然晾干后水解程度也没有明显增大. 由酸性硅烷溶液制得的薄膜中硅烷分子以Si―O―Si 键相互交联的程度比由碱性硅烷溶液制得的薄膜高. 硅烷膜降低了紫铜电极的腐蚀电流密度, 其保护效率分别为90.3%(酸性)和79.2%(碱性). 在3.5% (w) NaCl溶液中浸泡24 h后, 由酸性溶液制得的薄膜表现出更高的阻抗值, 而由碱性溶液制得的薄膜则基本失去了对基底的保护能力.     

Evaluation of Photocatalytic Activity of Transparent Anatase Nanocrystals-Dispersed Silica Films Prepared by the Sol-Gel Process with Hot Water Treatment

Anatase nanocrystals were precipitated mainly at the surface of the silica-titania gel films with hot water treatment, whereas the addition of poly(ethylene glycol) (PEG) in the films led to the dispersion of anatase nanocrystals in the whole of the films after the treatment. Both films with and without PEG showed high photocatalytic activities for acetaldehyde, NO _x and stearic acid in the gas-solid system, and for methylene blue and potassium iodide in the liquid-solid system. The addition of PEG improved the photocatalytic activities of the resultant films due to the smaller anatase crystallites and the porous film structure. The residual silica under-layer of the superficially anatase-precipitated films is expected to act as a protective one for an organic polymer substrate against the photocatalytic degradation.     

三甲基氯硅烷对纳米多孔二氧化硅薄膜的修饰

以正硅酸乙酯为先驱体,采用溶胶-凝胶法,结合旋转涂胶、超临界干燥工艺在硅片上制备了纳米多孔SiO2薄膜.用三甲基氯硅烷(TMCS)对该SiO2薄膜进行了表面修饰,采用FTIR、TG-DTA、AFM和椭偏仪等方法研究了TMCS修饰前后薄膜的结构、形貌、厚度与介电常数等性能.超临界干燥后的SiO2薄膜含有Si－O－Si与Si－OR结构,呈疏水性.在空气中250 ℃以上热处理后SiO2薄膜因含有Si－OH而呈吸水性. TMCS修饰后的SiO2薄膜在温度不高于450 ℃时可保持其疏水性和多孔结构. SiO2薄膜经TMCS修饰后基本粒子和孔隙尺寸增大,孔隙率提高,介电常数可降低至2.5以下.     

Synthesis,Characterization, and Hydrolytic Degradation of Polylactide/Poly(ethylene glycol)/Nano-silica Composite Films

Poly(lactic acid) (PLA)/PEG/nano-silica composite degradable films have been prepared by solvent casting method. IR measurements showed that vibration of C–O–C group was confined by silica network. SEM results showed that nano-silica particles were dispersed uniformly in the PLA/PEG matrix. TGA results indicated that the thermal decomposition temperature rose with the increase of nano-silica content. The tensile strength of composite film increased by the addition of nano-silica particles into PLA/PEG matrix. The degradation rate of PLA/PEG/nano-silica composites increased with the acidic medium of degradation. On the other hand, the slower degradation was obtained in the neutral buffer solution. PLA/PEG/nano-silica composites were found to exhibit almost similar degradation behavior as that of PLA/PEG films.     

Preparation, characterization, and surface modification of silver nanoparticles in formamide

The reduction of silver ions in formamide is shown to take place spontaneously at room temperature without addition of any reductant. The growth of Ag particles was found to be dependent on Ag+ ion concentration. In the absence of any stabilizer, deposition of silver film on the glass walls of the container takes place. However, in the presence of poly(N-vinyl-2-pyrrolidone) (PVP) or colloidal silica (SiO2), which are capable of stabilizing silver nanoparticles by complexing and providing support, a clear dispersion was obtained. The formation of the silver nanoparticles under different conditions was investigated through UV-visible absorption spectrophotometry, gas chromatography, and also electron and atomic force microscopic techniques. Atomic force microscopy results for silver films prepared in the absence of any stabilizer showed the formation of polygonal particles with sizes around 100 nm. Transmission electron microscopy results showed that the prepared silver particles in the presence of PVP were around 20 nm. The Ag nanoparticles get oxidized in the presence of chloroform and toluene. Surface modification of silver film was done in the presence of the tetrasodium salt of ethylenediaminetetraaceticacid (Na4EDTA). It was shown that the reactivity of the silver film increased in its presence. The Fermi potential of silver particles in the presence of Na4EDTA seems to lie between -0.33 and -0.446 V vs NHE.     

Successive interaction of pairs of soluble organics with nanosilica in aqueous media

Successive interaction of different pairs of water-soluble polymers (poly(ethylene glycol) (PEG), poly(vinyl pyrrolidone) (PVP), poly(vinyl alcohol) (PVA)), proteins (bovine serum albumin (BSA), ovalbumin, gelatin, and ossein), and smaller organics such as lecithin (1-stearoyl-2-oleoyl phosphatidylcholine, SOPC) and Aethonium (1,2-ethylene-bis(N-dimethyl carbodecyl oxymethyl) ammonium dichloride) with nanosilicas A-300 (S(BET)=232 and 297 m(2) g(-1)) and A-50 (S(BET)=52 m(2)g(-1)) was studied using dynamic light scattering, adsorption, and infrared (FTIR) spectroscopy methods. Time-dependent rearrangement of particle size distributions (PSDs) depicts appearance of both smaller and larger aggregates for silica/PEG(I-first adsorbate)/BSA(II-second adsorbate) and silica/PVP(I)/BSA(II) (i.e., BSA adsorbs onto PEG/silica or PVP/silica) than that for silica/organic compound I. However, in the cases of PVA(I)-BSA(II) and PVA(I)-SOPC(II) a similar effect is not observed because only increased aggregation occurs. The successive equilibrium adsorption of similar pairs shows a diminution of the adsorption of the second compound (gelatin, ovalbumin) with increasing amount of the first adsorbed polymer (PEG or PVP).     

Evaluation of the stability of nonfouling ultrathin poly(ethylene glycol) films for silicon-based microdevices

The creation of nonfouling surfaces is one of the major prerequisites for microdevices for biomedical and analytical applications. Poly(ethylene glycol) (PEG), a water soluble, nontoxic, and nonimmunogenic polymer has the unique ability of reducing nonspecific protein adsorption and cell adhesion and, therefore, is generally coupled with a wide variety of surfaces to improve their biocompatibility. The performance of these modified surfaces for long-term biomedical applications largely depends on the stability of these PEG films. To this end, we have investigated the stability of covalently coupled ultrathin PEG films on silicon in aqueous in vivo like conditions for a period of 4 weeks. The PEG-modified silicon substrates were incubated in PBS (37 degrees C, pH 7.4, 5% CO2) for different periods of time and then characterized using the techniques of ellipsometry, contact angle measurement, X-ray photoelectron spectroscopy, and atomic force microscopy. The ability of the PEG-modified surfaces to control protein fouling was examined by protein adsorption studies using fluorescein isothiocyanate labeled bovine serum albumin and ellipsometry. Furthermore, the ability of these films to control fibroblast adhesion was examined. Studies suggest that the PEG-modified surfaces retain their protein and cell repulsive nature even though the PEG film thickness decreases for the period of investigation.     

Oscillatory phenomena at polyvinylpyridine/silica interfaces

Oscillations of the aggregate sizes of SiO₂ particles covered by an adsorbed layer of poly(vinylpyridine) (PVP) at pH 3 with a periodicity of about 15 h were observed using a particle counting technique. The same oscillation was found for the contact angle values of water on the surface of Si wafers (with top silica layer) covered by adsorbed PVP as a function of exposure time in a PVP water solution.     

Effect of water-soluble polymers, polyethylene glycol and poly(vinylpyrrolidone), on the gelation of aqueous micellar solutions of Pluronic copolymer F127

The micellization of F127 (E(98)P(67)E(98)) in dilute aqueous solutions of polyethylene glycol (PEG6000 and PEG35000) and poly(vinylpyrrolidone) (PVP K30 and PVP K90) is studied. The average hydrodynamic radius (r(h,app)) obtained from the dynamic light scattering technique increased with increase in PEG concentration but decreased on addition of PVP, results which are consistent with interaction of the micelles with PEG and the formation of micelles clusters, but no such interaction occurs with PVP. Tube inversion was used to determine the onset of gelation. The critical concentration of F127 for gelation increased on addition of PEG and of PVP K30 but decreased on addition of PVP K90. Small-angle X-ray scattering (SAXS) was used to show that the 30 wt% F127 gel structure (fcc) was independent of polymer type and concentration, as was the d-spacing and so the micelle hard-sphere radius. The maximum elastic modulus (G(max)(')) of 30 wt% F127 decreased from its value for water alone as PEG was added, but was little changed by adding PVP. These results are consistent with the packed-micelles in the 30 wt% F127 gel being effectively isolated from the polymer solution on the microscale while, especially for the PEG, being mixed on the macroscale.     

Effect of γ irradiation on the surface properties of wet polysulfone films containing poly(vinylpyrrolidone)

In Japan, hemodialyzers are usually sterilized by γ irradiation. However, the polymer materials used in the dialysis membrane, such as polysulfone (PSf) and poly(vinylpyrrolidone) (PVP), undergo crosslinking or degradation on exposure to γ radiation. In the present study, we prepared PSf/PVP films (PVP content, 0–50 wt%) and used atomic force microscopy (AFM) to perform nanoscale evaluations of the effect of γ irradiation (25 and 50 kGy) on the surface properties of wet PSf/PVP surfaces. Force‐curve measurements were used to evaluate the hardness of and fibrinogen adsorbability on the wet PSf/PVP surface; fibrinogen adsorbability on the wet PSf/PVP surface was evaluated using AFM probes with fibrinogen immobilized on the tips of the probes. At PVP levels greater than 5 wt%, the wet PSf/PVP film surface was completely covered with hydrated and swollen PVP particles. The surface hardness of the wet PSf/PVP films exposed to 25‐kGy γ irradiation greatly decreased with increasing PVP content, whereas the surface hardness of the wet PSf/PVP films exposed to 50‐kGy γ irradiation did not decrease significantly. At higher PVP levels, the reduction in the fibrinogen adsorbability on a wet PSf/PVP film exposed to 25‐kGy γ irradiation was more significant than that on a wet PSf/PVP film exposed to 50‐kGy γ irradiation. PVP particles on the wet PSf/PVP film surface exposed to 50‐kGy γ irradiation did not show significant hydration and swelling because the polymer materials PVP–PSf and PVP‐PVP in these membranes has undergone excessive crosslinking due to γ irradiation. Copyright © 2010 John Wiley & Sons, Ltd.