Polymer brushes on hydrogen-terminated silicon substrates via stable Si—C bond

A universal and straightforward method for the preparation of polymer brushes via the formation of Si-C bond on silicon substrates through the UV-induced photopolymerization is demonstrated.     

Surface modification of thin polystyrene films

 The sulfonation of polystyrene (PS) films with 50 and 96% sulfuric acid as a function of time is presented. In contrast to previous literature reports, we showed that the treatment of PS films even with dilute sulfuric acid yields sulfonated surfaces after reaction times of 30 s–1 h. The hydrophilicity of the modified PS increased considerably in comparison to the unreacted PS films. X-ray photoelectron spectroscopy yielded evidence for the sulfonation of PS at the surface. Unreacted spin-coated PS films were very smooth, while modified PS showed some clumps dispersed on a flat surface, as analyzed by atomic force microscopy. The surface morphology was identified as a phase-separated system composed of domains of unreacted PS and a matrix of sulfonated PS by fluorescence microscopy using the positively charged dye rhodamine B. The adsorption of the polycation diallyldimethylammonium chloride on the sulfonated PS surface could be detected. The thickness of the adsorbed polycation was 2.2 nm. Received: 3 November 1998 Accepted in revised form: 23 February 1999     

Grafting of organosilane derived from 3-glycidoxypropyltrimethoxysilane and thiourea onto magnesium phyllosilicate by sol–gel process and investigation of metal adsorption properties

A layered inorganic–organic magnesium silicate (Mg-GTPS-TU) has been successfully synthesized by using sol–gel based precursor under mild temperature conditions and a new silylaing agent (GTPS-TU) derived from 3-glycidoxypropyltrimethoxysilane (GTPS) and thiourea (TU) as the silicon source. The hybrid material was characterized through elemental analysis, infrared spectroscopy, X-ray diffractometry, thermogravimetry, and carbon and silicon solid-state nuclear magnetic resonance spectroscopy. The result confirmed the attachment of organic functionality to the inorganic silicon network. The inter-lamellar distance for the hybrid material was found to be 18.8 Å. Metal adsorption characteristics follows Cr(III) >Mn(II)>Zn(II) with more affinity towards Cr(III) in dilute aqueous solution. Evaluation of thermodynamic parameters ΔH and ΔS for Cr(III) were found to be 25.44 J mol⁻¹ and 79.9 J mol⁻¹ K⁻¹, respectively, indicating adsorption process to be endothermic in nature. The negative value of ΔG indicated the feasibility and spontaneity of ongoing adsorption process at relatively higher temperature. The presence of multiple coordination sites in the attached organic functionality expresses the potentiality of the hybrid material containing new silylating agent for heavy cation removal from eco-system.     

Electrosynthesis and characterization of poly(3-methylthiophene) on different substrates

 We report on the study of the electropolymerization of 3-methylthiophene onto Pt, p-Si and indium-tin oxide deposited on polyester using quartz crystal microgravimetry, electrochemical and spectroelectrochemical measurements. We observe that potential variation during the galvanostatic electrodeposition is correlated with the nucleation process. The mass variation of poly(3-methylthiophene) is linear with the amount of the electrochemical charge whereas the absorbance variation curve shows two distinct slopes. The latter result has been explained in terms of conjugation length variation during polymer growth. Scanning electron microscopy analysis allowed the detection of morphological changes from a dense and compact structure to an open morphology when the poly(3-methylthiophene) film thickness increases. The roughness of the films did not change considerably with the substrate, as observed by atomic force microscopy. Absorption and photocurrent spectra at different film thicknesses show a shift of the peaks to lower wavelengths when the thickness increased, thus confirming the decrease of mean conjugation length in thicker films. Received: 1 September 1998 / Accepted: 11 November 1998     

Surface characterization of polyimide films

 Various kinds of poly(amide acid)s were prepared by the reaction of four kinds of acid dianhydride and three kinds of diamine in N,N-dimethylacetamide (DMAc). Polyimide films were prepared by casting the poly(amide acid) solution on soda glass substrates, followed by thermal imidization at various temperatures. Contact angles of polyimide films for the sides in contact both with air and with glass substrate (air side and glass side, respectively) were measured to evaluate the dispersive component (γ^D _S) and the nondispersive component (γ^P _S) of surface free energy (γ_S) of polyimide films. It was shown that, for the air side, γ^P _S value decreased greatly and γ^D _S values increased slightly with the development of imidization. Values of γ^P _S for the glass side were much higher than those for the air side. Poly(amide acid) solution was also cast on quartz glass and silicone rubber, and was thermally imidized. The γ^P _S for the quartz glass side was almost the same as that for the soda glass side. But the γ^P _S for the silicone rubber side was as low as the γ^P _S for the air side. Attenuated total reflection infrared spectroscopy of polyimide films showed that the degree of imidization for the glass side surface was not as high as that for the air side surface, and that the amount of polar groups for the glass side surface was higher than that for the air side surface. Among the various kinds of polyimides, there is a slight but clear difference in the values of γ_S and its components, which can be rationalized from the difference in the chemical structure. It was also found that thermal degradation and oxidation can be easily detected from the change of surface free energy and its components for the polyimide films after being treated at high temperatures in both air and vacuo. Received: 22 January 1998 Accepted: 10 March 1998     

Surface characterization of atomic oxygen beam-exposed polyimide films using contact angle measurements

Polyimide surfaces exposed to simulated low Earth orbit space environment, i.e., under hyperthermal atomic oxygen bombardment, were characterized by using atomic force microscopy, X-ray photoelectron spectroscopy, and contact angle measurements. The surface analytical results showed that the roughness and the O/C ratio at the atomic oxygen-exposed polyimide surface increased with increasing atomic oxygen fluence. The advancing and receding contact angles decreased with increasing O/C ratios at the polyimide surfaces. The Lifshitz-van der Waals component, the acid and base parameters of the surface free energy of polyimide films were calculated from the contact angles. The base parameter increased with increasing O/C ratio, whereas the acid parameter and the Lifshitz-van der Waals component did not show a remarkable change. These analytical results agree with the in situ XPS data showing the formation of surface functional groups due to atomic oxygen exposure. It was demonstrated in this study that the polyimide surface in a low Earth orbit space environment may become hydrophilic due to the bombardment by atomic oxygen. Received: 4 December 1999 Accepted: 31 August 2000     

Studies on the Surface Interaction Between MoO_3 and ZSM-11 Zeolite

A series of Mo-containing ZSM-11 zeolite catalysts has been prepared by calcining mixtures of MoO3 and ZSM-11 zeolite, and studied by using X-ray diffraction and infrared spectroscopy. It has been found that MoO3 can be well dispersed on ZSM-11 zeolite as a surface molybdenum species, and mostly within the zeolite cavities. With increasing the amount of dispersed MoO3, the zeolite framework is destroyed, and the crystallinity of the zeolite decreases. It seems that this perturbation is due to the strong interaction between dispersed MoO3 and zeolite framework.     

玻璃纤维表面的乙烯基单体接枝聚合

用玻璃纤维表面处理剂ＭＡＣ处理玻璃纤维后，再进行臭氧处理，使玻璃纤维的表面产生活性中心，引发苯乙烯、甲基丙烯酸甲酯、及丙烯酸等乙烯基单体在玻璃纤维表面上接枝聚合。接枝纤维的密度减小，对水的浸润性下降，红外光谱及扫描电镜观察证明玻璃纤维表面上接枝聚合物的存在。     

纳米晶钛酸铅表面态对介电性能的影响

将醋酸铅、钛酸四丁酯和硬脂酸在熔融状态下混合均匀后置于冷水浴中，使其凝固成凝胶，经不同温度焙烧，制成纳米晶PbTiO3.用X射线衍射光谱、红外光谱对产物进行表征.采用X射线光电子能谱和表面光电压谱对纳米晶PbTiO3表面状态分析,发现材料表面的不完整性主要是由氧空位造成.暴露在粒子表面的主要是金属离子.随着晶粒尺寸的减小，材料表面氧空位缺陷浓度增加，表面光伏效应增强，谱带变宽.纳米晶PbTiO3材料的表面状态对其极化性质有着重要的影响，使其静态介电常数远大于常规材料的静态介电常数.     

Highly conformal growth of microstructured polypyrrole films by electrosynthesis on micromachined silicon substrates

A novel technology for fabricating microstructured polypyrrole (PPy) films is presented based on PPy electrosynthesis on micromachined silicon substrates. PPy light-activated electropolymerization is performed on n-type microstructured silicon featuring lattices of square-like pores with pitch of 8 μm, size (s) of 5 μm, and depth (d) from 5 μm up to 50 μm. Scanning electron microscopy (SEM) highlights as light-activation allows a highly conformal polymer growth yielding a three-dimensional PPy structure perfectly replicating the silicon microstructure to be achieved up to high aspect-ratio (HR = d/s). Arrays of highly ordered PPy hollow microtubes with depth up to 50 μm and thickness up to 1 μm are obtained. Chemical analysis of microstructured PPy films is performed by X-ray photoelectron spectroscopy (XPS) and their electrochemical activity is verified by cyclic voltammetry (CV).     

硅的表面结构与电化学

从原子水平到微米尺寸,准确控制硅表面结构的精密加工,诸如无序的表面粗糙或者精细的图案,乃是电子元件性能及其可靠性的保证.硅在液中的湿清洗以及硅表面侵刻的电化学反应对硅表面结构的形成具有重要作用.近数十年来,有关阐明和控制硅/溶液界面上复杂的电化学反应及其与表面结构形成的关系已有大量的研究,相关研究成果已在新近编著成书.本文综合有关方面研究资料评述现代硅溶解及其形成的表面结构.     

Optimization of the electrokinetic sample introduction in capillary electrophoresis for the ultra trace determination of anions on silicon wafer surfaces

Summary A capillary electrophoretic method for the ultra trace determination of anions on silicon wafer surfaces is presented. In several sets of experiments designed according to the methodology of Taguchi, electrokinetic sample introduction with transient isotachophoretic preconcentration was simultaneously optimized for peak height, peak area, peak asymmetry, efficiency, peak resolution, and reproducibility of migration time and peak area. The blank reading of the method showed no cross contamination. Thus, a detection limit of 10 nmol L⁻¹ and a linear range from 50 to 500 nmol L⁻¹ were obtained and verified by two independent instruments. Furthermore, the method was applied to the determination of anions on wafers from a regular production line wetting the whole wafer surface with ultrapure water. The capillary electrophoretic results agree with those obtained by ion chromatography. Presented at the 21^st ISC held in Stuttgart, Germany, 15^th–20^th September, 1996.     

3D打印生物医用材料研究进展

3D打印(亦称增材制造)技术因其独特的材料成型优势,在组织工程、航空航天、汽车制造、以及电子工业等众多领域显示出巨大的应用潜力。然而,在实际生物医学应用中,3D打印生物器件和组织器官除了要求具有复杂的结构和优异的生物学性能外,其打印结构的表面性质也需满足某些特定的要求,如3D打印组织骨架和器官必须具有生物相容性、抗菌性及细胞粘附性等。因此,将3D打印与传统表面修饰技术相结合,在不改变材料三维结构的基础上调控其表面生物化学性质,从而赋予3D打印生物骨架器官多功能化,可实现更为广泛的应用。本文以3D打印生物骨架及器官的表面修饰为主要内容对就近年来3D打印生物医用材料的最新研究进展进行了综述。     

Role of the interaction between forming nanocrystals and glass surface on the structure and properties of ZnO-based films

The interaction between glass surface and forming nanocrystals plays the important role in the formation of thin ZnO coatings crystal structure. The comparative study of the crystal structure of thin ZnO-based films and powders having similar chemical compositions was performed with the use of SEM, XRD analysis, optical, and luminescent spectroscopy. The influence of different coatings parameters (chemical composition, thickness) on the spectroscopic and morphological properties of thin films and powders reveals the structural features of the interaction between forming ZnO nanocrystals and glass surface. ZnO–SnO₂ coatings and powders were prepared by liquid polymer-salt technique. This method provides the close contact between the coatings’ precursors with a surface of the glass during both the nucleation and the initial growth stage of forming oxide crystals. The interaction of nanocrystals and substrate surface is responsible for the texture formation in the ZnO films and determines some features of their optical properties.     

Surface structure and photoluminescence properties of AZO thin films on polymer substrates

Al‐doped zinc oxide (AZO) thin films were deposited on indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrates by radio frequency (RF) magnetron sputtering method at room temperature. The effects of film thickness on the surface structure and the photoluminescence properties of the films were investigated by atomic force microscopy (AFM), secondary ion mass spectroscopy (SIMS) and room temperature photoluminescence (PL). AFM analysis showed that the surface of all films was extremely flat and uniform at nanoscale. Root mean square (RMS) value of the surface roughness which scanned the surface area of 3 µm by 3 µm and grain size increased with increasing the film thickness. Thus, the surface morphology of the films became rough because of the coarse grains. The depth profile of AZO layers was analyzed by SIMS. It was found that the thickness of the AZO layer is almost same with the desired film thickness. The PL intensity of the dominant peak decreased and shifted slightly towards the shorter wavelengths with increasing the film thickness. According to the relationships between luminescence intensity and crystalline characteristics, it was observed that the intensity of the peak decreased by the increased surface area of the grains. Copyright © 2014 John Wiley & Sons, Ltd.     

水热法制备表面修饰的钛酸锶纳米微粉

以工业原料和常用试剂TiCl4、Sr(NO3)2和KOH为基础原料,通过添加表面活性剂十二烷基苯磺酸(DBS),采用水热法制备出表面包裹有DBS的钛酸锶纳米微粉,并应用红外光谱,X射线衍射谱,透射电子显微镜,热分析等一系列手段对其微结构进行了表征.结果表明:样品为表面包裹有DBS的钛酸锶纳米微粉,其形状较为规则,粒度分布较窄,单分散性较好.粒子的平均粒径为120nm,包裹膜的平均厚度为6nm左右.根据X光谱测量,表面修饰后的钛酸锶纳米微粉均以立方相存在.一般体相钛酸锶微粉为极性粉体.而表面修饰后的钛酸锶纳米微粉能够较为稳定地悬浮于非极性液体如正己烷中,说明SrTiO3粉体的极性表面被DBS包裹后,变为非极性.     

Surface modification of materials: Electrografting of organic films

The modification of surfaces is possible through a number of reagents (silanes, thiols, phosphonic acids, amines, and so on) among which diazonium salts have gained an increasing importance; this short review highlights the new achievements in this field.     

Adsorption of 3-mercaptopropyltrimethoxysilane and 3-aminopropyltrimethoxysilane at platinum electrodes

In this work we studied the self-assembled monolayer (SAM) formation of 3-mercaptopropyltrimethoxysilane [HS(CH₂)₃Si(OCH₃)₃] (MPS) and 3-aminopropyltrimethoxysilane [H₂N(CH₂)₃Si(OCH₃)₃] (APS) on platinum surfaces. We used X-ray photoelectron spectroscopy (XPS), specular reflectance FTIR, and electrochemistry to study the composition and structure of the self-assembly. XPS results of the Pt modified electrodes showed the presence of sulfur and nitrogen binding energy peaks indicating the presence of MPS and APS. The platinum substrates modified with MPS and APS showed IR absorption bands corresponding to the different stretches present in both compounds. Platinum disk electrodes, before and after being submerged in 1 mM solutions of MPS and APS for 24 h, were characterized voltammetrically by using 2.5 mM K₄Fe(CN)₆ in 0.1 M KCl, as the redox active couple. The MPS/Pt system is free of mass transfer effects, which are characteristic of pinhole defects in an MPS monolayer.     

Electrodeposition and characterization of PbSe films on indium tin oxide glass substrates

Electrodeposition of lead selenide (PbSe) thin films on indium tin oxide (ITO) covered glass is described. While disodium salt of ethylenediaminetetraaceticacid was used to complex the lead ions, well crystallized, nearly stoichiometric and mirror-like PbSe films were deposited on ITO glass in potentiostatic mode using aqueous acidic electrolyte containing Pb and Se precursors at different bath temperature. The improvement of crystallinity of the PbSe films deposited at different temperature was studied using X-ray diffraction and Raman scattering. The morphology and composition of the films were characterized by scanning electron microscopy and energy disperse analysis by X-ray, respectively. The optical property of the film was studied by optical measurement techniques.