添加离子强度对LBL聚电解质多层膜组装的影响

应用层层自组装技术(LBL)构筑聚电解质多层膜的过程中,组装溶液的离子强度对组装过程有特殊影响。采用紫外分光光度计与椭偏仪同时监测聚电解质沉积时间,聚阳离子(PDDA)浓度,特别是添加氯化钠(NaCl)对聚电解质成膜的影响。聚电解质分别沉积在石英基底和硅基底上,聚电解质膜厚度与聚电解质层数呈现良好的线性关系;随着聚电解质沉积时间的增加,聚电解质膜厚度逐渐增加,沉积时间为10min时聚电解质膜厚度最大;聚电解质膜的厚度随着PDDA浓度的增加呈现增长趋势;聚电解质溶液中加入NaCl,组装层数不大于10层时,聚电解质膜厚度随着NaCl浓度的增加而呈现线性增长。     

B-藻红蛋白多层复合薄膜的静电组装及其光谱特性

B-藻红蛋白是一种理想的生物光电材料.利用静电组装技术制备了聚二甲基二烯丙基氯化铵(PDDA)与B-藻红蛋白组装的多层复合薄膜.对薄膜的可见吸收光谱和荧光光谱进行了分析,结果表明:与B-藻红蛋白在溶液中的光谱特征相比,B-藻红蛋白在薄膜上的最大吸收峰由545 nm红移至553 nm,并在573 nm处产生了延迟荧光现象,且薄膜的最大吸光度和光致发射强度均与组装层数呈线性递增关系.随着薄膜组装层数的增加,倒置荧光显微镜能很好地观察到B-藻红蛋白在薄膜上出现明显的聚集体.     

PET基磁性膜材料的制备与性能表征

用共沉淀法制备出具有磁性的Fe3O4纳米粒子水溶液。红外光谱和XRD表明,纳米粒子是Fe3O4且其粒径在15 nm左右。通过磁滞回线得到纳米粒子比饱和磁化强度σr=56.58 emu/g。对PET薄膜进行预处理和阴离子化后,在PET表面交替吸附聚电解质聚二甲基二烯丙基氯化铵(PDDA)和纳米粒子水溶液,由于PDDA的存在,Fe3O4纳米粒子能均匀地被吸附在PET表面,形成PET基磁性膜材料,且吸附的强度较强。该材料的矫顽力为41.11 Oe,剩余磁化强度为0.66 emu,与Fe3O4纳米粒子一样,具有超顺磁性。     

CdTe量子点/PDDA多层膜的制备及对甲醛的检测

成功制备了L-半胱氨酸-CdTe/PDDA聚电解质多层膜(QDMF)气体传感器,并以此进行了有害气体甲醛的检测。以Te粉,NaBH4和CdCl2为原料制备前驱体,与修饰剂L-半胱氨酸混合,在氮气氛围下加热回流不同的时间得到所需量子点。通过带负点的量子点与带正电的PDDA之间的静电吸引进行层层自组装(LBL)得到聚电解质多层膜。并通过荧光光谱分析仪,紫外分光光度计等对量子点及多层膜进行表征,进一步证实本论文中制备的气体传感器性能稳定,并能灵敏的检测甲醛气体。     

膜厚对直流反应磁控溅射沉积NiO薄膜的结构与电致变色性能的影响

采用直流反应磁控溅射法在FTO玻璃基片上沉积了不同厚度的氧化镍(NiO)薄膜.用X射线衍射仪(XRD)、场发射扫描电子显微镜(SEM)、X射线光电子能谱仪(XPS)、台阶仪、紫外可见分光光度计、电化学工作站,研究了NiO薄膜厚度对其微观结构、形貌,以及电致变色性能的影响.结果表明,随着溅射时间增加,NiO薄膜厚度增加,试样的初始态可见光谱透过率逐渐降低,(200)晶面的XRD衍射峰强度逐渐增加;以1 M KOH溶液作为电解质,随着NiO薄膜厚度增加,薄膜电荷储存量逐渐增大.NiO薄膜厚度为920 nm的试样着色效率最高,达到了23.46 cm2/C;80 nm厚度的薄膜试样光学调制幅度最大,波长550 nm处为40.85％.薄膜越厚,着、褪色时间越长;所有试样着色时间均大于褪色时间,80 nm厚度的薄膜试样的着色、褪色时间最快,分别为4.47 s和2.28 s.     

光伏双层减反射膜的制备和性能研究

使用彩虹双层镀膜液在光伏玻璃基板上,利用辊涂工艺成功制备了由不同厚度和折光率二氧化硅层构成的双层减反射薄膜。通过对不同制备参数下得到的双层SiO₂减反射薄膜的微观结构、光学性质和组装的组件光伏性能进行对比研究,结果表明：在制备的底层和表层SiO₂膜厚分别为75 nm和127 nm时,减反射镀膜玻璃样品在波长380～1100 nm范围的平均透过率为94.33%(AM 1.5平均),封装的光伏组件也表现出了更高的外量子效率和组件功率。     

聚噻吩薄膜改性质子交换膜燃料电池用超薄炭纸

为提高质子交换膜燃料电池用超薄炭纸的力学性能,采用电化学聚合法在高通量超薄炭纸(0.339 g·cm~(-3),0.13 mm)内部原位聚合聚噻吩薄膜,制备聚噻吩薄膜改性超薄炭纸(PTCP)。通过红外光谱仪(FT-IR)和扫描电镜(SEM-EDS)分析表征了PTCP的结构和形貌特征,并对其物理性能和其作为气体扩散层的质子交换膜燃料电池的电池性能进行测试。结果显示,所制备的聚噻吩薄膜包覆在炭纤维、基体炭-炭纤维节点上,在炭纸内部形成厚度均匀的薄膜网络,且厚度随聚合电流增大仅从119 nm增厚至574 nm,使PTCP保留了高通量超薄炭纸的孔隙结构;这种包覆型薄膜网络结构能有效提高炭纸的力学性能。PTCP相比同密度普通超薄炭纸(CP1)具有更好的力学性能和透气性,聚噻吩薄膜厚度约为422 nm时,PTCP拉伸强度(39.63MPa)比CP1高出45%,透气率(2 959 m L·mm·cm~(-2)·h~(-1)·mm Aq)比CP1高出13.2%,PTCP所制备的质子交换膜燃料电池最高功率密度(728 m W·cm~(-2))较CP1高出25.3%。     

大自旋极化率半金属Fe_3O_4薄膜制备及其磁性能

采用磁控溅射法先在Si(100)基片上沉积适当厚度的Fe薄膜作为底层,通过对Fe底层厚度及氧气流量的控制,使底层Fe形成化学计量的无缓冲层的Fe3O4多晶薄膜。通过X射线衍射和磁强计分析了样品的结构和磁性能。结果表明:当初始氧气流量为1.5mL/s时,在15nm的Fe薄膜底层上可成功制备高晶粒织构的化学计量的Fe3O4薄膜。将Fe3O4薄膜应用到巨磁电阻(giant magnetoresistance,GMR)多层膜中,由于多层膜材料间电阻率的失配,利用Fe3O4半金属薄膜并不能获得预见的大GMR效应。     

氮化铝薄膜的光学性质

采用直流磁控溅射法在石英衬底上制备了氮化铝(AlN)薄膜.用X射线衍射仪分析了薄膜结构.利用椭圆偏振仪和紫外/可见/近红外分光光度计对AIN薄膜进行了相关光学性能的研究,获得到了薄膜的折射率随波长的色散关系曲线.在波长为250～1 000 nm,薄膜的折射率为1.87～2.20.结合透射光谱图,分析了AIN薄膜的光学性质.结果表明:利用磁控溅射方法可以获得(100)择优取向AIN薄膜;AIN薄膜在200～300 nm远紫外光范围内具有强烈的吸收,在300～1000 nm波长范围内具有良好的透过率.透射光谱图计算得到的薄膜厚度(427nm)与椭圆偏振拟合得到的薄膜厚度(425nm)一致.     

反应磁控溅射氧化钨电致变色薄膜厚度对结构、性能的影响

采用脉冲直流反应磁控溅射镀膜方法在FTO透明导电玻璃上制备厚度分别为50nm、100nm、150nm、200nm、250nm和300nm的氧化钨薄膜;采用XRD( X射线衍射) 和AFM（原子力显微镜）分析薄膜着色前后晶体结构和表面形貌的变化;采用电化学工作站和可见-近红外分光光度计对薄膜的循环伏安特性和光学性能进行测试。研究获得：不同厚度氧化钨薄膜均为结晶态,具有单斜晶系结构;随着薄膜厚度增加,薄膜结晶程度逐渐增加;薄膜着色/褪色循环中,不同厚度氧化钨薄膜均发生单斜晶系WO2.92与立方晶系WO3的可逆转变,产生晶格应变,并且随厚度增加,薄膜晶格应变先减小后增大,薄膜厚度为250nm时变色前后晶格应变最小,厚度进一步增加至300nm薄膜着色产生应变明显增大。在相同驱动电压下,随薄膜厚度增加,光学调制幅度（550nm）、着色效率先增大后减小,厚度为250nm时获得最大调制幅度76.01%,和着色效率21.04cm2/C;当厚度进一步增加至300nm时,薄膜褪色态透过率降低到49.30%后无法继续褪色,着色效率也开始下降。使用XPS进一步分析了薄膜着、褪色状态下W元素的化学态,发现300nm薄膜褪色后一部分W5+无法转变成W6+,导致薄膜仍为蓝色。     

Studies on Langmuir-Blodgett multilayer formation from preformed poly(N-alkylacrylamides)

The spreading behaviour of preformed poly(N-alkylacrylamides) having hexyl (PHA), octyl (POA), decyl (PDA), dodecyl (PDDA), tetradecyl (PTDA), hexadecyl (PHDA), and octadecyl (PODA) substituents on a water surface, and the properties of the Langmuir-Blodgett (LB) films deposited from these polymer monolayers were investigated. The surface pressure (F)-area (A) isotherms of the polymer monolayers were changed by the chain length of the substituents and the subphase temperature. The optimum conditions for the formation of a stable condensed monolayer from the polymer series of similar molecular weight (c. 4 × 10³) were found when the alkyl substituent was the dodecyl group (i.e. PDDA) and the subphase temperature was 19°C. The condensed monolayers of PDA, PDDA, and PTDA could be transferred successively on to solid supports such as quartz slides, giving the Y-type uniform polymer LB films. The successive uniform depositions of PDDA monolayer up to 320 layers were confirmed by a relationship between the absorbance at around 200 nm due to carbonyl group and the number of layers deposited. The thickness of PDDA monolayer in the LB film was 1.72nm which agrees with the length of the dodecylamide substituent. F-A isotherms, FTIR, and X-ray diffraction measurements support that the polymer main chains are laid horizontally on the water surface and the alkyl substituents are oriented perpendicular to the chain in the condensed monolayer (see Scheme 1).     

Composite graphitic nanolayers prepared by self-assembly between finely dispersed graphite oxide and a cationic polymer

Chemical flaking of graphite has been performed by reacting natural graphite with a strong oxidizing agent, NaClO₃/HNO₃. The formed hydrophilic, negatively charged graphite oxide (GO) colloids can be dispersed in water which allows the deposition of thin GO/cationic polymer (poly(diallyldimethylammoniumchloride, PDDA) multilayer films on a glass substrate by wet-chemical self-assembly. The feasibility of the charge-regulated layer-by-layer deposition is demonstrated by mutual charge titrations of the film-forming species. Visible-light spectroscopy revealed progressive growth of the film thickness with the number of deposition of steps, while XRD and AFM showed that partially exfoliated, highly anisometric (aspect ratio >50) graphite oxide platelet aggregates were deposited with an average thickness of the stacked graphite oxide platelets of 10 carbon layers (7.4 nm). Reduction of multilayer assemblies of GO and PDDA on glass yielded a non-conductive turbostratic carbon nanofilm. The original, conductive graphite-like structure was restored by reduction with N₂H₄ and annealing at 400 °C which, by gradual ordering of the carbon crystallites, caused a significant decrease in the resistivity.     

Ba(Zr0.3Ti0.7)O3薄膜的结构及性能

用溶胶-凝胶法分别在Pt/Ti/SiO2/Si和LaNiO3/Pt/Ti/SiO2/Si衬底上制备了锆钛酸钡[Ba(Zr0.3Ti0.7)O3,BZT]薄膜.相结构及介电性能研究表明:衬底和薄膜厚度对BZT薄膜性能具有显著影响.制备在LaNiO3/Pt/Ti/SiO2/Si衬底上的BZT薄膜具有(100)面的择优取向,其介电常数及介电损耗则随着薄膜厚度的增加而降低.对制备在Pt/Ti/SiO2/Si衬底上的BZT薄膜,在薄膜厚度低于500nm时,其介电常数随薄膜厚度增加而增加,大于500nm时又有所减小.     

LSMCD法制备纳米(Pb,La)TiO3薄膜

研究了利用液态源雾化化学沉积(LSMCD)法制备纳米(Pb,La)TiO3薄膜的工艺. XRD和SEM分析表明:沉积4次,采用RCA热处理,在Pt/Ti/SiO2/Si基板上成功制备出具有钙钛矿结构的、晶粒粒径约60nm、厚度约180nm的纳米颗粒PLT薄膜.该方法既可以较精确的控制薄膜的化学计量比及掺杂浓度,又可采用控制超声雾化沉积的时间和次数来有效的控制膜厚及晶粒的大小.该工艺的沉积速率约为3nm/min.     

LaNiO3缓冲层厚度对Ca0.4Sr0.6Bi4Ti4O15薄膜结构和电性能的影响

利用溶胶–凝胶法在Si（100）衬底上制备了具有（110）取向的LaNiO3薄膜,然后在LaNiO3/Si（100）上制备了Ca0.4Sr0.6Bi4Ti4O15（Ca0.4Sr0.6BTi）薄膜。研究了LaNiO3缓冲层厚度对Ca0.4Sr0.6BTi薄膜结构和电性能的影响。结果表明,当引入LaNiO3厚度为250 ...     

Aging and carbon dioxide plasticization of thin polyetherimide films

Industrial gas separation membranes have selective dense layers with thicknesses around 100 nm. It has long been assumed that these thin layers have the same properties as thick (bulk) films. However, recent research has shown that thin films with such thickness experience accelerated physical aging relative to bulk films and, thus, their permeation properties can differ significantly from the bulk. Thin films made from Extem^® XH 1015, a new commercial polyetherimide, have been investigated by monitoring their gas permeability. The permeability of the thin films is originally greater than the thick films but eventually decreases well below the permeability of the thick film. The CO₂ plasticization of Extem thin films is explored using a series of exposure protocols that indicate CO₂ plasticization is a function of film thickness, aging time, exposure time, pressure and prior history.     

Grain-Size Effects in YSZ Thin-Film Electrolytes

The transport properties of oxygen-ion conducting yttria-stabilized zirconia (YSZ)—featuring mean grain sizes from a few nm up to the μm regime—were studied with regard to grain-size effects. Chemically homogeneous, 8.3 mol% YSZ thin films (thickness approximately 400 nm) were processed on single-crystal sapphire substrates by a sol–gel method. The mean grain size d of the thin films was systematically adjusted to 5 nm≤ d ≤782 nm by (i) a rapid thermal annealing step for conversion into the oxide phase and (ii) a consecutive calcination step at 650°C≤ T _cal (24 h) ≤1400°C for grain growth. The quality of the thin films was examined with respect to chemical homogeneity, crystal structure, grain-size, and grain-boundary properties. Total and specific conductivities of the thin films were characterized by means of electrical impedance spectroscopy at 200°≤ T ≤400°C in ambient air, where a complex nonlinear least-squares approximation was applied to determine the bulk conductivity and the grain-boundary conductivity. Despite grain boundaries being free of second phases, oxygen transport was observed to be impeded by the grain boundaries as the specific grain-boundary conductivity was determined to be two orders of magnitude below the bulk conductivity for thin films with d >36 nm. The transport properties of nanoscaled YSZ thin films (5 nm≤ d ≤36 nm) were modeled by application of the brick-layer model indicating the absence of beneficial grain-size effects at the nanoscale.     

Thickness dependence of microstructure,dielectric and leakage properties of BaSn0.15Ti0.85O3 thin films

The BaSn_0.15Ti_0.85O₃ (BTS) thin films are prepared on Pt-Si substrates with thickness ranging from ~ 60?nm to ~ 380?nm by radio frequency magnetron sputtering. The effects of thickness on microstructure, surface morphologies and dielectric properties of thin films are investigated. The thickness dependence of dielectric constant is explained based on the series capacitor model that the BTS thin film is consisted by a BTS bulk layer and an interfacial layer (dead layer) between the BTS and bottom electrode. The thin films with thickness of 260?nm give the largest figure of merit of 76.9@100?kHz, while the tunability and leakage current density are 64.6% and 7.46?×?10^?7 A/cm² at 400?kV/cm, respectively.     

Spectroscopic ellipsometry characterization of TiO2 thin films prepared by the sol–gel method

TiO₂ thin films were prepared on SiO₂/Si(100) substrates by the sol–gel process. XRD results indicate that the major phase of TiO₂ thin films is anatase. The surface morphology and cross-section are observed by FE-SEM. The surface of thin films is dense, free of cracks and flat. The average grain size is about 60–100 nm in diameter. The thickness of single layer TiO₂ thin films is about 60 nm, which increases with the concentration of solution. Ellipsometric angles ψ, Δ are investigated by spectroscopic ellipsometry. The optical constant and the thickness of TiO₂ thin films are fitted according to Cauchy dispersion model. The results reveal that the refractive index and the extinction coefficient of TiO₂ thin films in wavelength above 800 nm are about 2.09–2.20 and 0.026, respectively. The influences of processing conditions on the optical constants and thicknesses of TiO₂ thin films are also discussed.     

A microstructural study of polystyrene—polyether sulphone polymer blends

Polystyrene (PS)-polyether sulphone (PES) polymer blend thin films were prepared for investigation in a scanning transmission electron microscope. The microstructures of PS-PES films (prepared by drawing from solutions at temperatures above ambient) of three different compositions were characterized: (1) 75 wt% PS-25 wt% PES, (2) 50 wt% PS-50 wt% PES, and (3) 25 wt% PS-75 wt% PES. For films prepared at ～ 40°C all three compositions exhibited microstructures consisting of spherical inclusions, ranging from ～0.2μm to ～ 1.2μm in diameter. The microscope used here was equipped with an energy-dispersive X-ray spectrometer, and this was employed to determine the chemical content of the inclusions and the matrix material. From X-ray analysis, it was found that films (1) and (2) consisted entirely of PES-rich inclusions, while film (3) contained both PS-rich and PES-rich inclusions. In addition, these analyses revealed that films (2) and (3) possessed a ‘mixed’ PS-PES matrix phase. At the other temperatures for film preparation some significant differences in morphology were observed, reflecting the different rates of solvent evaporation.