Morphological effect on spectral property of poly(9,9-dihexylfluorene-alt-2,5-dihexyloxybenzene) films

In this study the optical property and film morphology of a conjugated polymer, poly(9,9-dihexylfluorene-alt-2,5-dihexyloxybenzene) (PF6OC6), are investigated. It is found that the intensity of the 0-1 emission relative to the 0-0 emission in the PL spectra and the full width at the half-maximum (fwhm) of PL spectra of the PF6OC6 films decrease firstly and then increase with increasing the annealing temperature. The polymer films also exhibit different morphological features after annealing at different temperatures. The optical and morphological results suggest that the vibronic structure of PF6OC6 is closely related to the film morphology, and its formation is enhanced in the amorphous (or less ordered) films and inhibited in the ordered films.     

Fabrication and Properties of Conducting Polypyrrole/SWNT‐PABS Composite Films and Nanotubes

We report the electropolymerization and characterization of polypyrrole films doped with poly(m‐aminobenzene sulfonic acid (PABS) functionalized single‐walled nanotubes (SWNT) (PPy/SWNT‐PABS). The negatively charged water‐soluble SWNT‐PABS served as anionic dopant during the electropolymerization to synthesize PPy/SWNT‐PABS composite films. The synthetic, morphological and electrical properties of PPy/SWNT‐PABS films and chloride doped polypyrrole (PPy/Cl) films were compared. Characterization was performed by cyclic voltammetry, atomic force microscopy (AFM), scanning electron microscopy (SEM) and Raman spectroscopy. SEM and AFM images revealed that the incorporation of SWNT‐PABS significantly altered the morphology of the PPy. Cyclic voltammetry showed improved electrochemical properties of PPy/SWNT‐PABS films as compared to PPy/Cl films. Raman Spectroscopy confirmed the presence of SWNT‐PABS within composite films. Field effect transistor (FET) and electrical characterization studies show that the incorporation of the SWNT‐PABS increased the electronic performance of PPy/SWNT‐PABS films when compared to PPy/Cl films. Finally, we fabricated PPy/SWNT‐PABS nanotubes which may lead to potential applications to sensors and other electronic devices.     

Influence of plasticizers and crosslinking on the properties of biodegradable films made from sodium caseinate

Plasticized protein films were prepared by the casting method from water solution of sodium caseinate and plasticizers with the aim to obtain environmentally friendly materials for packaging applications. Mechanical properties (tensile strength, elongation and Young’s modulus) of caseinate based films were determined versus ratio of protein to plasticizer, plasticizer type and relative humidity conditions. Among the different polyol-type plasticizers tested, glycerol (Gly) and triethanolamine (TEA) were the most efficient for the improvement of mechanical properties (high strains for low stresses). Further, chemical crosslinking between formaldehyde (HCHO) and free amino groups (ε-NH₂) of sodium caseinate was performed to increase water resistance of TEA plasticized films. Optimal mechanical properties, i.e. elastic modulus of 105 MPa, tensile strength of 8-9 MPa for elongation at break about 110-125% were obtained for HCHO/ε-NH₂ ratios higher than 1.35. Protein specific water solubility was determined from a 280 nm absorbance. For convenient crosslinker (HCHO) content sodium caseinate solubility can be lowered to less than 5 wt% after 24 h immersion in water.     

Measurement of the Rates of Diffusion of Halomethanes into Polymer Films Using ATR-FTIR Spectroscopy

Polymer-modified attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and FEWS (fibre-optic evanescent wave) spectroscopy have been very successful to date for sensitive detection of organic pollutants in water utilising the mid-infrared (MIR) region of the electromagnetic spectrum (4000-400 cm^?1). This sensing approach involves the use of different polymer films for preconcentration with optimisation of the sensor related to the rate of diffusion of solvent molecules into these polymer films. Compounds such as chloroform, bromoform, bromodichloromethane and dibromochloromethane which are collectively referred to as trihalomethanes (THMs) were analysed in this work. A gaseous phase experimental design was used and from experimental data the rate of diffusion of each of the halomethanes was quantified based on a Fickian type diffusion model. Individual diffusion coefficient values were found to be in the range 3.38 E-10 ± 0.01 E-10 to 4.72 E-08 ± 0.42 E-08 cm² s^?1. Multicomponent effects were observed for mixtures of compounds diffusing into polyisobutylene and ethylene-propylene copolymer.     

Sulfur-Containing Vinyl Monomers. XV. Kinetic Study of Radical Polymerization of Vinyl Mercaptobenzothiazole and Its Copolymerization

A kinetic study of radical polymerization of vinyl mercaptobenzothiazole (VMBT) with α,α′-azobisisobutyonitrile (AIBN) at 60°C was carried out. The rate of polymerization (R_p) was found to be expressed by the rate equation: R_p = k[AIBN]^0.5 [VMBT]^1.0, indicating that the polymerization of this monomer proceeds via an ordinary radical mechanism. The apparent activation energy for overall polymerization was calculated to be 20.9 kcal/mole. Moreover, this monomer was copolymerized with methyl methacrylate, acrylonitrile, vinyl acetate, phenyl vinyl sulfide, maleic anhydride, and fumaronitrile at 60°C. From the results obtained, the copolymerization parameters were determined and discussed.     

热处理对WO3纳米薄膜结构及其气致变色性能的影响

以钨粉和过氧化氢溶液为原料, 采用溶胶凝胶法制备了WO3溶胶, 并结合提拉镀膜法, 分别在普通玻璃载玻片和抛光硅片上制备了掺钯气致变色WO3纳米结构薄膜; 并分别在50, 150, 250, 350和450 ℃的空气氛围中对薄膜进行了热处理. 采用IR、双椭圆偏振光谱仪、AFM和XRD分析了薄膜的性质和微观结构, 观察了薄膜的表面形貌, 根据所得数据讨论了不同热处理温度对薄膜的结构和气致变色性能的影响.     

超疏水多孔阵列碳纳米管薄膜

碳纳米管由于具有特异的力学[1] 、光学[2 ] 、电学[3,4 ] 和磁学性质[5] ,使其在锂离子电池[6 ] 和平板展示器[7] 等方面呈现出广泛的应用前景 .Ebbesen等[8] 对无序碳纳米管材料的浸润性进行了详细研究 ,发现其很容易被水润湿 .然而 ,阵列碳纳米管膜的浸润性研究尚未见报道 .固体表面的浸润性主要由表面化学组分和几何结构两方面控制 .通常 ,加大表面粗糙度可以增强其浸润性 [9～ 16 ] .近来 ,超疏水表面 (即与水的接触角大于 1 5 0°的表面 )的研究显示了广泛的应用背景[13～ 16 ] .这种表面通常可由增加表面粗糙度和降低表面能来制备[1…     

间苯二酚-甲醛凝胶自发成膜技术研究

 以间苯二酚和甲醛为原料，对水相溶胶-凝胶聚合自发成膜技术获得间苯二酚-甲醛(RF)凝胶薄膜进行了研究。主要研究了溶胶-凝胶过程中冰醋酸（HAC）含量和反应温度对凝胶过程的影响，分析了RF有机凝胶自发成膜的形成机理。IR和SEM分析表明，所得到的凝胶膜具有典型的RF有机气凝胶结构，薄膜厚度大约为50 μm，膜由直径10 μm左右的粒子组成，没有观察到明显的孔洞结构。分析认为，在间苯二酚和甲醛占总溶液的质量分数为67％左右及控制pH值在一定的酸性范围，RF凝胶自发成膜过程和机理可以用RF凝胶的收缩机理加以解释，RF自发膜的表面形貌及形成机理与均匀泡沫的连续相分离机理类似。     

Growth of InN films and nanorods by H-MOVPE

InN films and nanorods were grown by hydride metalorganic vapor phase epitaxy (H-MOVPE) and the effects of growth temperature, and NH₃/TMIn and HCl/TMIn ratios on morphological dependences were studied. The growth habit of InN varied from thin film to microrod to nanorod to no deposition as the growth conditions were changed about transition from growth to etching conditions. The growth and etch regimes were also predicted by chemical equilibrium calculations of In–C–H–Cl–N-inert system. The optical properties of InN nanorods and columnar structured films were measured by room temperature PL and a maximum intensity was observed at 1.08 eV for both structures.     

Natural-based plasticizers and biopolymer films: A review

In recent years, much attention has been focused on research to replace petroleum-based commodity plastics, in a cost-effective manner, with biodegradable materials offering competitive mechanical properties. Biopolymers have been considered as the most promising materials for this purpose. However, they generally present poor mechanical properties regarding processability and end-use application, since the fragility and brittleness exhibited during thermoformation can limit their potential for application. In order to overcome this problem, plasticizers are added to provide the necessary workability to biopolymers. This class of products became more visible when biodegradable additives and plasticizers also became the focus of material scientists. The use of natural and/or biodegradable plasticizers, with low toxicity and good compatibility with several plastics, resins, rubber and elastomers in substitution of conventional plasticizers, such as phthalates and other synthetic conventional plasticizers attracted the market along with the increasing worldwide trend towards use of biopolymers. Here we discuss the main results and developments in natural plasticizer/synthetic and biopolymer-based films during the last decades.