嵌段共聚物非共价修饰碳纳米管/环氧纳米复合材料的性能

采用原子转移自由基聚合法(ATRP)合成了嵌段共聚物聚苯乙烯/苯乙烯基芘丁酸酯(PS-b-PAH),并将其对碳纳米管(MWNTs)进行非共价键表面修饰(PS-b-PAH/MWNTs),采用浇注成型法制备了MWNTs/环氧树脂(EP)纳米复合材料。透射电镜表明,嵌段聚合物PS-b-PAH包覆于MWNTs表面,形成有机包覆层的厚度为17.7nm。嵌段聚合物修饰有效地改善了碳纳米管在环氧基体中的分散性并提高了PS-b-PAH/MWNTs/EP纳米复合材料的导电性。当PS-b-PAH/MWNTs质量分数为0.8%时,复合材料的阈渗值pc=0.124%(质量分数),较MWNTs/EP(pc=0.625%)降低了5倍;电导率为10-3S/cm,较MWNTs/EP高了3～4个数量级。     

耐水性有机硅改性自交联丙烯酸酯乳液的合成EI北大核心CSCD

以丙烯酸酯类单体、二缩三丙二醇二丙烯酸酯(TPGDA)、3-(2,3-环氧丙氧)丙基三甲氧基硅烷(KH560)为主要原料,通过半连续种子乳液法制备得到耐水性有机硅改性自交联丙烯酸酯乳液。通过傅里叶变换红外光谱、透射电镜、差示扫描量热分析、热重分析、粒径分析等表征了产物的结构形貌及相关性能;并对聚合条件进行初步探索,研究了不同比例的乳化剂、引发剂对乳液性能的影响;同时讨论了TPGDA及KH560对乳液粒径、稳定性以及乳胶膜的耐水性、吸水率和接触角等性能的影响。结果表明,采用种子乳液法作为聚合方式,当乳化剂质量分数为4%,引发剂质量分数为0.3%,TPGDA质量分数为0.15%,KH560质量分数为0.35%时,制备的硅丙乳液具有优良的稳定性,平均粒径为109.1nm,乳胶膜的水接触角为81.5°,吸水率为8.67%,耐水性高达168h。     

耐水性有机硅改性自交联丙烯酸酯乳液的合成

以丙烯酸酯类单体、二缩三丙二醇二丙烯酸酯(TPGDA)、3-(2,3-环氧丙氧)丙基三甲氧基硅烷(KH560)为主要原料,通过半连续种子乳液法制备得到耐水性有机硅改性自交联丙烯酸酯乳液。通过傅里叶变换红外光谱、透射电镜、差示扫描量热分析、热重分析、粒径分析等表征了产物的结构形貌及相关性能;并对聚合条件进行初步探索,研究了不同比例的乳化剂、引发剂对乳液性能的影响;同时讨论了TPGDA及KH560对乳液粒径、稳定性以及乳胶膜的耐水性、吸水率和接触角等性能的影响。结果表明,采用种子乳液法作为聚合方式,当乳化剂质量分数为4%,引发剂质量分数为0.3%,TPGDA质量分数为0.15%,KH560质量分数为0.35%时,制备的硅丙乳液具有优良的稳定性,平均粒径为109.1nm,乳胶膜的水接触角为81.5°,吸水率为8.67%,耐水性高达168h。     

疏水性增透聚酯薄膜的制备及应用

以聚苯乙烯为大分子引发剂,丙烯酸聚硅氧烷酯为单体,通过原子转移自由基聚合制备苯乙烯-丙烯酸聚二甲基硅氧烷酯共聚物。将所得聚合物旋涂于聚对苯二甲酸乙二醇酯(PET)薄膜表面,研究共聚物中不同硅氧烷含量对聚酯薄膜性能的影响。通过核磁共振和红外光谱表征了丙烯酸聚硅氧烷酯单体及与苯乙烯共聚产物的结构,结果表明实验成功制备出了苯乙烯共聚物;凝胶渗透色谱结果表明聚合物的相对分子质量与设计相对分子质量相接近,并且相对分子质量分布系数均小于1.4,说明反应具有一定可控性;紫外-可见光分光光度计结果表明聚合物的折射率随着嵌段聚合物中硅氧烷含量的降低而增加;通过场发射扫描电镜(FE-SEM)对改性前后的聚酯薄膜进行观察,结果显示聚酯薄膜表面形成了蜂窝状多孔结构,从而有效改善了薄膜的透光性。总体研究结果表明,随着共聚物中硅氧烷含量的增加,聚酯薄膜的水接触角和透光率均呈先增后减的趋势。当共聚物中硅氧烷含量为19.6%时,PS-PDMS嵌段共聚物折射率为1.38,涂覆在PET表面后薄膜透光率达到92.6%,水接触角为120°。     

TPU/OMMT纳米复合膜的制备及性能研究

采用溶液共混法将有机改性蒙脱土(OMMT)引入热塑性聚氨酯(TPU)中制备了TPU/OMMT纳米复合膜,采用全反射傅里叶变换红外光谱仪、X射线衍射仪、扫描电子显微镜、热重分析仪对TPU/OMMT纳米复合膜的结构、微观形貌及耐热性能进行了表征,研究了OMMT含量对纳米复合膜力学性能、吸水率和紫外透光率的影响。结果表明：当OMMT含量低于5%(质量分数)时,OMMT均匀地分散在TPU中,呈完全剥离状态;OMMT可以有效提高TPU/OMMT纳米复合膜的拉伸强度、韧性和耐热性,降低吸水率且保持良好的透明度。     

有机硅-丙烯酸酯水分散液的合成及表征

以端乙烯基硅氧烷齐聚物(NS)、甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA)为原料,通过乳液共聚合,制备了有机硅-丙烯酸酯二元共聚水分散液。考察了不同单体配比对水分散液及成膜物性能的影响。通过动态光散射仪、透射电子显微镜等对水分散液进行了表征,发现共聚物乳胶粒子粒径较小,均在30nm～60nm范围;水分散液成膜物透明、光滑、力学性能好。当共聚物中有机硅含量达到10%(质量分数,下同)时,成膜物对水的接触角已超过100°,接近纯有机硅的接触角,表明端乙烯基硅氧烷齐聚物的引入赋予了薄膜良好的表面拒水性能。     

纳米TiO2对大豆蛋白/聚乙烯醇 复合薄膜的影响研究

将经过超声波分散的纳米Ti O2加入大豆蛋白/聚乙烯醇混合膜液中在玻璃板上流延成型,以复合薄膜的抗张强度、断裂伸长率、透光率和吸水率为评价指标,研究了纳米Ti O2的粒径、添加质量分数以及分散剂种类对复合薄膜各指标的影响。结果表明:在优化大豆蛋白/聚乙烯醇复合薄膜的性能中,纳米Ti O2的粒径、添加质量分数以及分散剂种类都对其有一定的作用,且当纳米Ti O2的粒径为30 nm、添加质量分数为1.50%、分散剂为PVPK-30时,所得复合薄膜的综合评价分数最高;相较未添加纳米Ti O2的薄膜,复合薄膜的抗张强度由4.6 MPa增加至5.4 MPa,断裂伸长率由56.3%增加至87.4%,透光率由13.7%增加至28.9%,吸水率由48.7%下降至36.3%。     

有机氟改性超支化水性聚氨酯的合成与性能

以异佛尔酮二异氰酸酯(IPDI)、二羟甲基丙酸(DMPA)和二乙醇胺(DEOA)为原料,合成出了超支化聚氨酯核HBPU-0;以IPDI、聚醚多元醇(N220)、DMPA及甲基丙烯酸羟乙酯(HEMA)等原料合成带有双键的线型聚氨酯,然后将线型聚氨酯接枝到HBPU-0上,再与甲基丙烯酸六氟丁酯(HFMA)反应,制备了有机氟改性的超支化水性聚氨酯。通过红外光谱和核磁共振对聚合物进行表征,并研究了加入HEMA对乳液粒径、乳液的机械稳定性以及胶膜的力学性能、水接触角、吸水率和热性能的影响。测试结果表明,随着有机氟含量的增加,乳液水接触角和粒径增大,胶膜的拉伸强度升高,断裂伸长率下降,吸水率下降。加入有机氟后,胶膜耐热性有所提高,当有机氟含量为10%时,综合性能最佳,此时乳液粒径为145nm,胶膜的水接触角为93.4°,拉伸强度为11.7MPa,断裂伸长率为360%,48h吸水率为6.12%。     

核壳型无皂含氟丙烯酸酯共聚乳液的合成

以甲基丙烯酸全氟辛基乙酯(PFEA)为含氟丙烯酸酯单体,烯丙氧基壬基酚聚氧乙烯(10)醚单磷酸(ANPEO10-P1)为反应型乳化剂,采用预乳化、半连续法聚合方式合成了具有核壳结构的无皂含氟丙烯酸酯共聚乳液。研究了乳化剂用量对聚合反应以及PFEA用量对乳胶膜吸水率和接触角的影响。结果表明,当反应型乳化剂ANPEO10-P1用量为5%(质量分数,下同),PFEA用量为6%时,得到的乳液粒径分布窄,稳定性好,乳液成膜后吸水率低,达到8.8%,对水的接触角达到了109.5°,表现出优异的疏水性能。     

凝胶型LED封装材料基础聚合物的制备及性能

过开环聚合制备了透明的聚(二甲基-甲基苯基-甲基乙烯基)硅氧烷共聚物,考察了聚合条件对产物结构与性能的影响.以该共聚物为基础聚合物,含氢硅油为交联剂,在Karstedt催化剂作用下硅氢加成硫化成型,获得折射率n<'25><,D>>1.5000,透光率大于90%(400 nm～800 nm,10 mm)的凝胶型发光二级管...     

单硬脂酸甘油酯改性蓖麻油基水性聚氨酯的制备与性能研究

目的 使用单硬脂酸甘油酯(GMS)对蓖麻油基水性聚氨酯进行改性,增强其防水、耐热和力学性能。方法 使用丙酮法合成不同GMS含量的蓖麻油基水性聚氨酯乳液,进行乳液粒径测定和稳定性试验;使用浇铸法制作薄膜,并进行铅笔硬度测试、力学性能测试、吸水测试、接触角测试、热重测试、DSC、FTIR测试。分析薄膜表面硬度、力学性能、耐水性能、热稳定性、耐热性能和内部结构。结果 当GMS的−OH的摩尔分数为25%时薄膜综合性能最佳,此时膜的抗拉强度为(9.37±1.28)MPa,弹性模量为(250.55±34.05)MPa,薄膜的吸水率降低到12%,薄膜的水接触角为92°。GMS的加入,增加了薄膜的玻璃态转化温度和铅笔硬度,但热稳定性有所下降。结论 GMS的加入增强了蓖麻油基水性聚氨酯的耐水、耐热和力学性能。     

Optical properties of hafnium oxide thin films and their application in energy-efficient windows

Thin films of hafnium oxide were deposited by electron beam evaporation. The films were characterized using X-ray diffraction, X-ray photoelectron spectroscopy and normal incidence transmittance. The films were amorphous, stoichiometric, and transparent down to a wavelength of 300 nm. The optical properties of the films, including the refractive index, the absorption index and the bandgap, were determined. The refractive index, in the visible, was relatively high (1.89). The direct bandgap was found to be 5.41 eV. Absorption was insignificant for wavelengths above 250 nm. A heat mirror was built based on the hafnium oxide/silver/hafnium oxide/glass system. This heat mirror was found to be transparent in the visible with an average transmittance of 72.4%, and reflective in the near infrared (wavelength = 700–2000 nm) with an average reflectance of 67.0%. Such a heat mirror can be used in applications involving energy-efficient windows.     

High performance of GaN-based flip-chip light-emitting diodes with hole-shape patterned ITO ohmic contact layer and AgIn reflector

The enhancement of light extraction efficiency is observed when the hole-shape patterned ITO ohmic contact layer and AgIn reflector is adopted in GaN-based flip-chip (FC) light emitting diodes (LEDs). ITO layer (140 nm) and AgIn (200 nm) was deposited on the top of p-GaN by in-line DC sputtering and electron beam evaporating system, respectively. The ITO ohmic contact layer showed a low specific contact resistance of 2.66 x 10(-5) Omega cm(-2) and high transmittance of >85% at visible spectral regions. The AgIn reflector exhibited a low specific contact resistance of 1.90 x 10(-5) Omega cm(-2) and high reflectance of approximately 84% at visible spectral regions. Comparing with unpatterned ITO/AgIn layer, the optical output power of GaN-based FC LEDs improves approximately 30% by the adoption of micro size hole-shape patterned ITO ohmic contact layer and AgIn reflector.     

Effect of heat treatment temperature on properties of electrosprayed paperboard

The purpose of this study was to investigate the effect of additional heat treatment on the properties of paperboard electrosprayed with poly(lactic acid) (PLA). For this study, paperboards electrosprayed with PLA at 1%, 2%, and 3% (w/v) were further heat‐treated at 170°C, 180°C, 190°C, and 200°C for 1 minute. Physical properties, such as basis weight, thickness, and colour of electrosprayed paperboards, were investigated. For mechanical properties, folding endurance and bursting strength of treated paperboard was tested. Water resistance property was observed through contact angle, and water absorption was monitored by Cobb test. In addition, water vapour transmission rate tests were also conducted. Surface characteristics were investigated using a scanning electron microscope and roughness tester. After heat treatment, PLA particles on the paperboard surface melted and formed a smoother continuous surface; this contributed to lower water contact angles and significantly lower water absorption. Furthermore, the higher the concentration of PLA, the better the water resistance. Moreover, heat treatment temperature between 180°C and 200°C could significantly improve the water vapour barrier and water resistance properties. Temperature and treatment time could not be further increased, as the electrosprayed paper substrate was damaged and became yellowish. In addition, for the mechanical properties, an increase in the heat treatment temperature improved the bursting strength; however, a reduction in folding endurance was observed, because the melted PLA particles were absorbed deeper into the paper structure and made the whole matrix more brittle.     

具有梯度渐变折射率的超疏水减反膜的制备及其性能

具有梯度折射率的减反膜可以在更宽光谱波段和更大入射光角度实现减反射性能。本研究利用溶胶-凝胶和溶剂热法分别合成实心氧化硅(SiO₂)、空心氧化硅(H-SiO₂)和空心氟化镁(MgF₂)溶胶, 利用浸渍-提拉法在玻璃双面镀制SiO₂/H-SiO₂/MgF₂梯度折射率薄膜。结果表明, 在380~1600 nm波长, 镀膜基片在光垂直入射时透光率高达99.88%, 当光以0°~45°入射时, 平均透光率均高于97.85%, 即使光以75°入射时, 最高透光率仍达95.51%。同时发现, 经十六烷基三甲氧基硅烷(HDTMOS)修饰, 薄膜疏水角达到150.6°, 显示出良好的疏水自清洁效果。     

Oxidation of evaporated porous silicon rugate filters

Rugate filters are thin-film optical interference coatings with sinusoidal variation of the refractive index. Several of these filters were fabricated with glancing angle deposition, which exploits atomic competition during growth to create nanoporous materials with controllable effective refractive index. This method enables the fabrication of devices with almost arbitrary refractive index profiles varying between the ambient, 1.0, and the index of the film material, in this case silicon with an index of 4.0 (at 600 nm). As these filters are inherently porous, oxidation of the silicon can occur throughout the device layer, and here we study the intentional oxidation of silicon filters by high-temperature reaction with gaseous oxygen. We find that a significant portion of the silicon filter oxidizes in approximately 10 min when heated to 600 degrees C-650 degrees C in an oxygen environment; oxidation then continues slowly over several hours. The presence of water vapor has little apparent effect on the oxidation reaction, and attempts to oxidize with ozone at room temperature were unsuccessful. As silicon filters oxidize to become silica, spectral blueshifts and increased short-wavelength transmittance are observed. Measured and calculated transmittance spectra generally agree, although the lack of absorption and dispersion in the theoretical model limits detailed comparison.     

Wetting behavior of oleophobic polymer coatings synthesized from fluorosurfactant-macromers

Architecturally similar monomers were copolymerized with a water-oil discriminate fluorosurfactant to create hydrophilic-oleophobic coatings. Acrylic acid, hydroxyethyl methacrylate, and methyl methacrylate were used as comonomers with the fluorosurfactant macromer. The homopolymers of the selected comonomers are water-soluble, water-swellable, and water-insoluble, respectively, thus coupling the surfactant monomer in varying concentration within polymers of varying hydrophilicity. Wetting behavior of water and hexadecane were examined as a function of copolymer composition, thus revealing critical structure-property relationships for the surfactant-based system. Acrylic acid copolymers and hydroxyethyl methacrylate copolymers both exhibited a hexadecane contact angle which exceeded the water contact angle. This condition predicted an ability to "self-clean" oil-based foulants. The most oleophobic of the self-cleaning copolymers had an advancing hexadecane contact angle of 73° and an advancing water contact angle of 40°. It was determined that the advancing and receding water and hexadecane contact angle response varies montonically for each copolymer type as the surface concentration of the surfactant is varied. Comparing between copolymer types revealed large differences in wetting response. Methyl methacrylate copolymers with 2.8 mol % surfactant had advancing water contact angle 82° and advancing hexadecane contact angle 26°, which is neither oleophobic nor self-cleaning. In contrast, acrylic acid copolymers with 3.1 mol % surfactant had advancing water contact angle of 44° and advancing hexadecane contact angle of 52°, creating a self-cleaning coating. Thus, the nature of the comonomer exerts a greater influence than the surfactant content on the wetting behavior and self-cleaning ability of the final coating.     

Fabrication of superhydrophilic and antireflective silica coatings on poly(methyl methacrylate) substrates

Silica nanoparticles of ca. 20 nm in size were synthesized, from which hierarchically porous silica coatings were fabricated on poly(methyl methacrylate) (PMMA) substrates via layer-by-layer (LbL) assembly followed by oxygen plasma treatment. These porous silica coatings were highly transparent and superhydrophilic. The maximum transmittance reached as high as 99%, whereas that of the PMMA substrate is only 92%. After oxygen plasma treatment, the time for a water droplet to spread to a contact angle of lower than 5° decreased to as short as 0.5 s. Scanning and transmission electron microscopy were used to observe the morphology and structure of nanoparticles and coating surfaces. Transmission and reflection spectra were recorded on UV–vis spectrophotometer. Surface wettability was studied by a contact angle/interface system. The influence of mesopores on the transmittance and wetting properties of coatings was discussed on the basis of experimental observations.     

高折光紫外光-热双重固化树脂的合成及其性能

合成了同时具有光固化基团(双键)和热固化基团(环氧)的高折光紫外光-热双重固化树脂,用红外光谱、核磁共振氢谱、质谱表征了树脂结构。配制了一系列紫外光-热双重固化体系,用红外光谱表征了固化过程特征吸收峰的变化;测试了紫外光-热双重固化膜的凝胶率、吸水率、体积收缩率、折光率和表面水接触角。结果表明,高折光紫外光-热双重固化树脂固化后凝胶率可以达到96.4%以上,吸水率在0.87%以下,体积收缩率在6.87%以下,水接触角在60°左右,为亲水性表面。在相同稀释剂条件下,与双酚A环氧丙烯酸单酯光-热固化膜相比,其折光率由1.3014提高到1.5723。