一种交联聚合物薄膜的表面引发聚合制备及其摩擦磨损性能

采用活性可控的表面引发原子转移自由基聚合方法,在硅片表面制备了聚3-(三甲氧基硅)丙基甲基丙烯酸酯聚合物刷,其中产物侧链的三甲氧基硅基团提供相邻分子间相互交联的位点而形成聚合物薄膜;采用衰减全反射红外光谱仪和原子力显微镜分析了薄膜的化学结构和微观形貌,利用椭圆偏光测厚仪和接触角测量仪测定了其厚度和水接触角,并利用微观和宏观摩擦磨损测试装置评价了薄膜的摩擦磨损性能.结果表明,所制备的薄膜具有聚合物的结构特征以及良好的减摩抗磨特性,且其抗磨能力随着厚度增加而增强.     

光波导共振技术结合比色法检测葡萄糖溶液的浓度

利用比色法结合双面金属包覆波导构建了一种高灵敏度的光波导振荡场传感器. 将葡萄糖溶液与氧化酶试剂混合, 使葡萄糖溶液显色并注入波导结构, 采用波长为650 nm的激光入射于波导表面, 经角度扫描产生衰减全反射(ATR)吸收峰, 通过ATR吸收峰的极小值来检测葡萄糖溶液的浓度变化. 实验结果表明, 该技术对葡萄糖溶液浓度的分辨率达到111 nmol/mL, 其灵敏度高于分光光度计.     

TiO_2纳米多孔薄膜漏模光波导共振传感器研究小分子的光谱灵敏度

在玻璃基片上溅射约50nm厚的金膜,在掺有P123聚合物的TiO2胶体溶液中浸渍提拉基片,经高温热处理后获得厚度约为210nm的TiO2纳米多孔薄膜。以此双层膜为漏模光波导芯片,并结合卤钨灯光源、CCD光谱仪、棱镜耦合器以及流动测试槽构建了基于Kretschmann结构的光谱测量式漏模光波导共振传感器。以非吸附型蔗糖水溶液为折射率液体,测试了传感器的折射率灵敏度。结果表明,在给定溶液折射率范围(1.3330～1.3557)内,漏模光波导共振波长随着折射率的升高而线形增大。以离子型表面活性剂和溴百里酚蓝为小分子吸附质,考察了传感器对小分子吸附的响应特性。结果表明,与只有一层金膜的SPR传感器相比,多孔薄膜漏模传感器对小分子吸附质的灵敏度大幅提高,这由于小分子在TiO2多孔薄膜导波层内的大量吸附。     

ATR-FTIR光谱技术在聚合物膜研究中的应用

红外光谱是聚合物研究中常用的一种表征手段，而衰减全反射红外光谱（ATR-FTIR）更是由于在研究聚合物薄膜方面具有显著的优势而被广泛使用。逐层组装（layer-by-layer Assembly）技术是一种常用的组装聚合物超薄膜的方法，ATR-FTIR光谱技术的引入可以在获取膜组装过程中相应信息的同时有效地避免表征过程中对样品的损害。另一方面，ATR-FTIR方法与二维相关光谱技术（two-dimensional correlation spectroscopy, 2D correlation spectroscopy）相结合也是研究小分子（主要是水分子）在聚合物薄膜中的渗透行为的有效手段。本文对ATR-FTIR的基本原理和显著特点作了介绍，并以实例阐述该方法在逐层组装技术和水分子在薄膜内渗透行为研究两方面的应用。     

利用双光子聚合技术制备的聚合物型光栅光波导和耦合光栅

自从1970年报道第一个波导光栅之后,人们又很快发现了它在集成光学上的应用潜力．目前,对廉价、可靠和高效的集成光学器件的需求使研究者们开始注意聚合物材料．因此有关各种聚合物型的波导光栅的制备和光学性能的研究备受注意。现在,紫外光漂白、激光切除和光致二色型等一系列方法已经被用于聚合物波导光栅的制备,同时,聚合物波导光栅的光控光开关、光子禁带效应和谐振光栅等各种光学性质也有广泛的研究．迄今,聚合物波导光栅的制备方法基本上属于物理方法,并没有在材料内部引发本质性的化学改变,因此所制备的器件的长期稳定性难以保证．如利用紫外光漂白和光致二色性法制备的波导光栅,前者是靠材料的饱和光吸收引发的折射率变化,后者则是靠聚合物内的染料分子的光致定向作用产生的周期性结构。     

聚合物与纳米晶的杂化及性能优化

聚合物-纳米晶杂化材料因结合了有机和无机材料的优点而逐渐地受到了人们普遍的关注,聚合物为纳米晶的形成与生长提供了优良的环境,纳米晶的引入同样也增加和强化了聚合物的功能特性.如聚硫代氨基甲酸酯与TiO2杂化的高折射率薄膜,该薄膜不仅保持了原有的性能,而且有较高的折射率.此外,还有许多不同纳米粒子与不同聚合物的杂化体系.如...     

可交联聚甲基丙烯酸甲酯的合成、表征及在阵列式波导光栅中的应用

合成了含环氧基团的可交联的甲基丙烯酸甲酯和甲基丙烯酸环氧丙酯的共聚物[Poly(MMA-co-GMA)],通过FTIR,NMR,GPC,DSC和AFM等技术对其进行了表征. 结果表明,所合成的聚合物材料具有较好的成膜性; 通过热固化使引入的环氧基团开环交联,该聚合物的玻璃化转变温度(Tg)比固化前提高了24 K,同时有效地降低了聚合物的双折射率. 用Poly(MMA-co-GMA)作为包层材料,双酚A型环氧化合物作为高折射率材料, 将其引入到包层材料中形成芯层材料的折射率在波长1.55 μm处可调,其范围是1.483~1.588. 采用旋涂、 铝掩膜和氧反应离子刻蚀的方法(RIE)制得了阵列式光波导. 测试结果表明,制作的波导在1.55 μm处实现了光的单模传输,光损小于3.0 dB/cm.      

磷酸铁纳米薄膜复合光波导氨气传感元件的制备

将硝酸铁和甲醇、磷酸溶液按一定比例混合后,通过旋涂法制备了磷酸铁（FePO₄）纳米薄膜,测定了匀胶机转速对膜厚及烘干温度对膜厚和折射率的影响,并发现薄膜的烘干温度超过150 ℃时,薄膜的厚度（130 nm）和折射率(1.7)变化不大。将该薄膜固定在钾离子交换玻璃光波导表面,研制出FePO₄膜/K⁺交换玻璃复合光波导。酸碱指示剂溴百里酚兰（BTB）作为敏感试剂,固定在复合光波导表面,研制了BTB膜-FePO₄膜/K⁺交换玻璃复合光波导氨气传感元件。采用自装的光波导气体传感检测系统对不同浓度的氨气进行了检测。结果表明,该传感元件能够检测0.35 mg/m³浓度的氨气,并具有响应（10 s）及恢复（90 s）速度快、可逆性好、连续使用等特点。     

聚3-羟基丁酸酯薄膜结晶的ATR-FTIR研究

使用匀胶机(spincoater),通过溶液铸膜的方法,在铝箔基板上制备出具有不同厚度的聚3羟基丁酸酯(PHB)薄膜.20℃室温条件下,通过衰减全反射傅立叶红外光谱(ATRFTIR)原位观测了不同厚度薄膜的结晶过程,并通过偏光ATRFTIR对薄膜中PHB分子的取向进行了研究.ATRFTIR原位观测结果显示,PHB在薄膜中的结晶速率以及结晶度均随着薄膜厚度的减小而逐渐降低;同时,偏光ATRFTIR测试结果表明,随膜厚减小,薄膜中结晶部分的PHB分子逐渐倾向于沿垂直于基板表面方向取向,膜越薄,倾向越明显.可以认为,PHB分子与基板间的相互作用以及扩散控制结晶导致了上述现象的产生.     

静电自组装铁电超薄膜及其性能研究

利用静电自组装方法在石英玻璃表面交替沉积聚二烯丙基二甲基氯化铵(PDDA)和聚偏氟乙烯(PVDF)超薄膜,制得PDDA/PVDF铁电复合超薄膜.通过石英晶体微天平实时监测超薄膜的沉积,研究了超薄膜的表面形貌、结构及电性能.结果表明,自组装每层PVDF超薄膜的厚度为7.5 nm;PDDA/PVDF铁电复合超薄膜的表面平整、均匀,其中C1s的光电子能谱与极化处理后充负电荷的PVDF铁电聚合物一致,但F1s由于溶解再组装过程而降低了0.3 eV;静电自组装材料纳米级的薄膜厚度和聚合物的络合作用导致了铁电复合超薄膜的非晶结构和高的表面电阻率.     

Laser reflectometry: Examination of the influence of some assumptions and approximations to calculate the adsorption from the reflectometric signal

The adsorption density of a polymer was calculated from the output of a reflectometric instrument, using the model described by Dijt et al. taking into account a step layer profile of the adsorbed film, in order to weight the influence of several experimental parameters (refractive index and thickness of the substrate, concentration of the polymer solution) and hypothesis (thickness of the adsorbed layer, linear dependence of the output on the surface excess). Calculated data were backed with measurements in an impinging jet cell, using two adsorption systems: the cationic poly(allyl amine, HCl) on SiO₂ and the anionic poly(styrene sulfonate) on a polyamide 6-6 covered silicon substrate. We established the limit of a linear response of the reflectometric signal versus adsorption density, which depends on the refractive index of the substrate and on the concentration of the polymer solution. Calculations showed that an increase in the assumed adsorbed film thickness between 5 and 20 nm caused a decrease of about 13% in the calculated surface excess at the plateau of the isotherm for PSS. At concentrations of the polymer solution above 1 or 2 g L⁻¹, we found experimental circumstances where the reflectometric output was negative or null, although adsorption was taking place. This was an effect of the high refractive index of the solution.     

Preparation of refractive index matching polymer film alternative to oil for use in a portable surface-plasmon resonance phenomenon-based chemical sensor method

In order to simplify the procedure for assembling a surface-plasmon resonance (SPR) sensor, a refractive index matching polymer film was prepared as an alternative to the conventionally used matching oil. The refractive index matching polymer film, the refractive index of which was nearly equal to the prism and sensor chip material (a cover glass) of the SPR sensor, was prepared by casting a tetrahydrofuran solution of poly (vinyl chloride) (PVC) containing equal weights of dioctyl phthalate and tricresyl phosphate. The refractive index matching polymer film was found to have a refractive index of 1.516, which is identical to that of the prism and the cover glass used for the present SPR sensor. The utility of the matching polymer film for the SPR sensor was confirmed by the detection of anti-human albumin, based on an antigen-antibody reaction.     

Effect of molecular weight and temperature on physical aging of thin glassy poly(2,6-dimethyl-1,4-phenylene oxide) films

The effects of polymer molecular weight and temperature on the physical aging of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) is examined. Gas permeability and refractive index were monitored during the aging process for PPO film samples at three aging temperatures below the glass transition temperature. Comparisons between the two samples of PPO that differ widely in molecular weight reveal an insignificant difference, which support the notion that above a critical molecular weight range there is little influence on aging rate. Increased temperature, over the limited range of 35–55 °C, results in higher aging rates for films made from both PPO materials. The rate of aging decreases strongly with increasing film thickness over the range examined, ∼0.4–25 μm. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1390–1398, 2007     

Optical anisotropy of polymeric films measured by waveguide propagation mode determination

Extruded thin films of a liquid-crystalline charge-conjugated rigid-rod polymer poly(p-phenylenebenzobisthiazole), PBT, and a semicrystalline thermoplastic polyethylene-terephthalate (Mylar) were fabricated and examined for film thickness, refractive index, and linear attenuation coefficient. Optical waveguide modes were successfully induced on the polymeric films using a prism coupler at λ = 633 and 1300 nm. Highly consistent thickness values were obtained for the polymeric films. In addition, the anisotropic nature of the optical properties was determined using TE and TM propagation modes. A refractive index as high as 2.3 was observed on PBT film. The refractive index data suggested that the PBT and Mylar films were optically anisotropic with refractive indices n? (out-of-plane) invariably smaller than n∥ (in-plane). Large anisotropy was also discovered in the linear attenuation coefficient α, with α_∥/α_? ≈ 50 for the Mylar films. Complementary polarimetric and spectroscopic interference measurements were also applied to investigate the optical anisotropy of the extruded polymeric films. © 1992 John Wiley & Sons, Inc.     

High Photosensitive Sol-Gel Hybrid Materials for Direct Photo-Imprinting of Micro-Optics

Sol-gel derived inorganic-organic hybrid materials (HYBRIMERs) were found to have high photosensitivity arising from large changes in refractive index and volume upon exposure to light. These materials combined different photosensitive mechanisms due to the presence of polymers and silica in the HYBRIMER structure. Photo-induced densification of a germanium-doped HYBRIMER gave an increase in refractive index accompanying a volume contraction. A methacrylate HYBRIMER was decomposed by long UV illumination, giving a low refractive index and resulting in a reduction in film thickness. Also, photo-initiators were locked inside the methacrylate HYBRIMER during illumination, giving a simultaneous increase in the refractive index and film thickness. Direct photo-imprinting using the photosensitive HYBRIMER was demonstrated for simple fabrication of gratings, microlens, and waveguides using a photomask, a phase mask, an interferometer, and laser writing.     

Anode Magnetron Enhanced DC Glow Discharge Processes for Plasma Surface Cleaning and Polymerization

The objective of this study was to examine some fundamental factors involved in the design and construction of the anode magnetron dc glow discharge processes as well as its performance in plasma cleaning and polymerization. Those advantages of anode magnetron include the capability of the magnetron to operate at low pressure, as well as decreasing the thickness of cathode dark space, i.e., the negative glow which contains a higher concentration of ions and active species was more closely to the cathode surface, which makes the plasma surface cleaning and polymerization an effective and uniform processes. The deposition rate at a given discharge power is increased by the presence of anode magnetrons, and is also much higher relative to rf and af. The refractive index of dc plasma film at a given polymer thickness (such as TMS, 70 nm, RI: 2.4) is higher than rf, af, and cascade arc plasma (RI: 1.6–1.7).     

Analyzing refractive index profiles of confined fluids by interferometry part II: Multilayer and asymmetric systems

Methods for determining the substrate properties and the optical thickness of thin films or any variation in the refractive index of a fluid or film near a surface for unknown 5-layer symmetric and 3-layer asymmetric interferometers are presented. Both systems can be fully resolved without any known layer properties and without contact or confining the films. The method was tested using realistic simulated interferometer data, and was found to consistently yield accurate values for all desired properties. The method was experimentally validated through analysis of an asymmetric three layer interferometer system of linear polyethyleneimine (LPEI) adsorbed onto mica substrates of differing thickness and identical refractive index. The results were in excellent agreement with the dry polymer film properties measured using conventional SFA contact measurements. More complicated systems were also evaluated for feasibility, and any additional parameter specifications required for analysis were determined. The utility of this method is broad, as a single experiment in a laboratory setting can independently provide non-contact film properties and the effects of confinement on the film structure, which can be correlated to a simultaneously measured interaction force profile.     

High on-state clarity polymer dispersed liquid crystal films

Abstract

Results are presented which show that the on-state clarity of a UV cured polymer dispersed liquid crystal (PDLC) film depends on the refractive index of the final polymer in the PDLC film, the ordinary refractive index of the liquid crystal, the solubility of the liquid crystal in the prepolymer and the rate at which the film is cured. Liquid crystal mixtures for use in PDLC films are chosen such that the ordinary refractive index of the liquid crystal is equal to the refractive index of the polymer matrix. It has been shown previously that a large quantity of liquid crystal remains dissolved in the polymer matrix, thus increasing the mismatch between the refractive index of the polymer and the ordinary refractive index of the liquid crystal and therefore reducing the on-state clarity. For liquid crystal mixtures which have high solubility in the prepolymer (>60 per cent) the mismatch in the refractive indices can be very large and the on-state clarity of the resulting film can be very poor (T _on<70 per cent). Results are presented which show that it is possible to increase the on-state clarity of such films by increasing the rate at which these films cure. If the liquid crystal is less soluble in the prepolymer (<45 per cent), a PDLC film formed from such a liquid crystal/ prepolymer system often has very good on-state clarity (T _on>75 per cent) be it cured slowly or quickly. Results are also presented which show that in order to achieve a true measure of on-state clarity it is necessary to use a small collection angle (<3°) in the detecting optics. If larger collection angles are used, the photodetector collects light which is scattered out of the specular beam, thus leading to a false measure of on-state clarity.     

Tuning the optical properties of mesoporous TiO2 films by nanoscale engineering

The optical properties of spin-coated titanium dioxide films have been tuned by introducing mesoscale pores into the inorganic matrix. Differently sized pores were templated using Pluronic triblock copolymers as surfactants in the sol-gel precursor solutions and adjusted by varying the process parameters, such as the polymer concentration, annealing temperature, and time. The change in refractive index observed for different mesoporous anatase films annealed at 350, 400, or 450 °C directly correlates with changes in the pore size. Additionally, the index of refraction is influenced by the film thickness and the density of pores within the films. The band gap of these films is blue-shifted, presumably due to stress the introduction of pores exerts on the inorganic matrix. This study focused on elucidating the effect different templating materials (Pluronic F127 and P123) have on the pore size of the final mesoporous titania film and on understanding the relation of varying the polymer concentration (taking P123 as an example) in the sol-gel solution to the pore density and size in the resultant titania film. Titania thin film samples or corresponding titanium dioxide powders were characterized by X-ray diffraction, cross-section transmission electron microscopy, nitrogen adsorption, ellipsometery, UV/vis spectrometry, and other techniques to understand the interplay between mesoporosity and optical properties.     

The stability of high refractive index polymer materials for high-density planar optical circuits

Owing to the structural flexibility, easy processing and fabrication capabilities, polymers are being increasingly attractive for a variety of optical applications. In order to increase the integration density of such optical circuits, higher index contrasts and, thus, polymers with considerably higher refractive index are essentially needed. An organometallic polymer and a conventional epoxy material are combined to form a compatible high index material. When cured at elevated temperatures, the organometallic polymer decomposes to form a highly dispersed metal oxide phase that imparts high index properties to the polymer films. These hybrid high refractive index polymer films must be stable in patterning of optical waveguide structure for photonic manufacturing. In this paper, we report the stability and optical characterization study of a modified organometallic high refractive index polymer film in manufacturing of optical waveguide devices.