Sonochemical preparation of photochromic nanocomposite thin film based on polyoxometalates well dispersed in polyacrylamide

Novel photochromic nanocomposite thin film containing phosphotungstic acid entrapped in polyacrylamide was prepared using ultrasound technique. TEM image revealed that the polyoxometalates nanoparticles with narrow size distribution were finely dispersed in polymer matrix. IR spectra showed that the Keggin geometry of polyoxometalates was still preserved inside the composite film and strong Coulombic interaction was built between heteropolyoxometalates and polyacrylamide via hydrogen bond. It was found that the thermal stability of the hybrid film was lower than that of pure polymer but the film was stable enough for photochromic application from the TG-DTA curves. The transparent film changed from colorless to blue under UV irradiation and showed reversible photochromism. The bleaching process occurred when the film was in contact with air or O₂ in the dark. The photoreduced process was in accordance with radical mechanism.     

Preparation and surface properties of the polysiloxane material modified with fluorocarbon side chains

The novel polysiloxane material modified with fluorocarbon side chains was synthesized. FTIR, FNMR were used to characterize the copolymer structure. The emulsion of the modified polysiloxane was prepared. The reflectance spectrum of the dyed polyester fabric treated with the polymer was also discussed. The effect of the modified polysiloxane on the color fastness of the dyed polyester fabric was investigated. The results show that the novel polysiloxane material modified with fluorocarbon side chains had excellent surface activity. It did not affect the shade of color and the fastnesses of the dyed fabrics and could improve the handle of fabrics. The treated fabric with the modified polysiloxane showed excellent repellency to water.     

Transparent h-BN/polyacrylamide nanocomposite hydrogels with enhanced mechanical properties

In this study, a facile way has been proposed to prepare transparent, tough and flexible polyacrylamide (PAM) hydrogels which is composed of a dually crosslinked single network by chemical crosslinking of N,N'-methylenebisacrylamide (BIS) and physical crosslinking of hydrophilic hexagonal boron nitride (hBN) nanosheets. The resulting h-BN/PAM nanocomposite hydrogels are highly transparent, and exhibit significantly enhanced mechanical properties compared to the dark (GO)/PAM nanocomposite hydrogels or chemical crosslinking PAM hydrogels. Thus it opens up new opportunities for developing nextgeneration transparent, tough and flexible hydrogels that hold great promise in such important applications as light responsive soft robot and liquid microlenses.     

金纳米粒子的表面等离子体共振吸收光度法研究和分析应用

在阴离子表面活性剂十二烷基苯磺酸钠存在下的水溶液中，基于金纳米粒子产生的表面等离子体共振吸收的原理，提出了一个分光光度方法。结果表明在524nm处的共振吸收强度与金质量浓度在2．4-120μg/mL范围内服从比尔定律。其线性回归方程为：c＝55．58A 0．78，相关系数为0．9998。方法适用于载金炭中的金分析。     

New insight into surface properties of LB film of an amphiphilic terpolymer

Amphiphilic terpolymer(TPR) exhibits good film-forming behavior on pure water observed by means ofπ-A isotherms.To gain insight into physical properties of TPR,the films have been deposited on silicon substrates at different surface pressure by Langmuir-Blodgett(LB) technique.It was found that the increase in peak intensities of stretching mode was due to orderly packing of the films.The contact angles increased with increasing surface pressure,indicating an increase in hydrophobicity due to dense packing of chains of TPR.The cyclic voltammetric measurements indicated that TPR showed good current shielding effect for electron-transfer.In a word,LB films of TPR can produce a variety of structures with varied topography,enabling us to control not only the functionality of the surface,but also the interfacial transport characteristics.     

Role of ionic species and valency on the viscoelastic properties of partially hydrolyzed polyacrylamide solutions

The effects of ionic species and valency on the viscoelastic properties of partially hydrolyzed polyacrylamide solutions were examined. Two viscoelastic parameters were considered, i.e., average relaxation time, _M ⁰ and steady state compliance, Je⁰. Both these parameters are independent of ionic species of monovalent salts. However, _M ⁰ decreases with increasing salt concentrations. Divalent salts reduce the values of _M ⁰ by as much as 10 times. On the other hand, Je⁰ is independent of salt concentrations and valency. The effects of monovalent salt on three different polyacrylamide samples of varying degree of hydrolysis and MW were also examined.     

Structural,surface, optical,and antimicrobial characterization of I2/Polymethyl methacrylate and CuS/I2/polymethyl methacrylate thin films

In this study, I₂/PMMA and CuS/I₂/PMMA thin films were produced by Chemical Bath Deposition (CBD) on polymethyl methacrylate (PMMA) substrates, and their physicochemical and antimicrobial properties were analyzed. The film's surface tensions were characterized by KSV instruments, and the surface tensions for plain PMMA, I₂/PMMA, and CuS/I₂/PMMA thin films were 30.27, 28.77, and 31.86 mN/m, respectively. The I₂ and CuS/I₂ structures in the XRD patterns are amorphous. After coating CuS, the long rod-like extension structures are formed; spherical shapes form some agglomeration in some regions to SEM images. Chemical analysis was performed with an EDX spectrometer attached to SEM. The thicknesses and surface roughnesses of I₂/PMMA and CuS/I₂/PMMA thin films were determined to be 50.34 nm, 1126 nm; 62.03 nm and 204.99 nm via AFM, respectively. The optical spectra of the films were recorded in the range of 300–1100 nm with a UV-VIS spectrophotometer. The antibacterial and antifungal properties of I₂ and CuS coating were evaluated against facultative gram-negative E. Coli and C. Albicans. The coated films exhibited excellent antimicrobial performance.     

Film analysis employing subtarget effect using 355 nm Nd-YAG laser-induced plasma at low pressure

The applicability of spectrochemical analysis for liquid and powder samples of minute amount in the form of thin film was investigated using ultraviolet Nd-YAG laser (355 nm) and low-pressure ambient air. A variety of organic samples such as commercial black ink usually used for stamp pad, ginseng extract, human blood, liquid milk and ginseng powder was prepared as film deposited on the surface of an appropriate hard substrate such as copper plate or glass slide. It was demonstrated that in all cases studied, good quality spectra were obtained with very low background and free from undesirable contamination by the substrate elements, featuring ppm or even sub-ppm sensitivity and worthy of application for quantitative analysis of organic samples. The proper preparation of the films was found to be crucial in achieving the high quality spectra. It was further shown that much inferior results were obtained when the atmospheric-pressure (101 kPa) operating condition of laser-induced breakdown spectroscopy or the fundamental wavelength of the Nd-YAG laser was employed due to the excessive or improper laser ablation process.     

Polyethylene surface enhancement by corona and chemical co-treatment

Corona and chemical treatment worked cooperatively for increasing and stabilizing the polyethylene film surface energy. Gentle and varied corona discharge treatment conditions were applied for each polyethylene film to reach 40?dynes/cm. A rather low blending amount of additive could stabilize the film surface energy obviously. Compared with neat PE film, of which the surface energy decreased to 36?dynes/cm at the 12th day, films blended with 1000?ppm A7-OH or PE-PEG_4k-PE showed stable surface energy (36–38?dynes/cm) over 150?days. The influence of industrial applied slipping agent was investigated as well. Morphological and chemical changes were studied by X-ray photoelectron spectroscopy (XPS) and Atomic Force Microscope (AFM). The surface energy was determined by the dyne pens. Mechanism investigation of hydrophilization and hydrophobic recovery processes showed that proper crystallization behavior and enough CO groups on the film surface guarantee satisfactory stability of the surface energy.     

Synthesis and surface properties of a fluorinated polyether

A new polyether consisting of alternate fluorinated/non-fluorinated phenylene units in the backbone has been synthesized via polycondensation of an AB monomer. At room temperature, the polymer film exhibits a low surface energy that is comparable to poly(tetrafluoroethylene) (PTFE). However, as the temperature is raised above a particular level, the surface energy of the polymer films starts to increase. Morphological measurements suggest that a smooth thin polymer film can be formed by solvent casting, but it spontaneously dewets the substrate surface when thermally annealed.     

Effect of oligomeric surface modifying agent on electro-optical properties of polymer dispersed liquid crystal

In order to lower the driving voltage of polymer dispersed liquid crystal (PDLC), an oligomeric surface modifying agent (SMA) which is a fluoroalkyl terminated polyurethane (PU) oligomer has been synthesized and added to polyurethane acrylate (PUA) resin. With the addition of SMA, contact angle of the resin surface with an LC drop increased and domain size decreased significantly due to the enrichment of SMA molecules at the surfaces. Operating voltage decreased up to 5 phr SMA and increased beyond this content. Regarding the effect of SMA molecular weight, lower molecular weight drove the shutter at lower operating voltage, indicative of more enrichment of the SMA molecules at the surfaces.     

Effects on surface properties of natural bamboo fibers treated with atmospheric pressure argon plasma

Argon plasma at atmospheric pressure was used to improve the wettability and dyeability of natural bamboo fibers. Optical emission spectroscopy (OES) was employed to characterize the discharge. SEM and scanning probe microscopy (SPM) analyses show that the fiber surface becomes rougher after plasma treatment because of the effects of plasma bombardment and etching. The wettability and dyeability are significantly enhanced after plasma treatment. Longer treatment time, leading to rougher surface, results in better surface wettability and dyeability. These results reveal that atmospheric pressure argon plasma treatment is an effective method to improve the performance of bamboo fibers. Copyright © 2006 John Wiley & Sons, Ltd.     

Spin-coated methacrylic acid copolymer thin films for covalent immobilization of small molecules on surface plasmon resonance substrates

Hydrophilic copolymers of methacrylic acid and ethylene glycol dimethacrylate are simply and rapidly prepared as thin films by spin-coating on gold-coated glass slides with a concurrent photo-crosslinking step. Coating techniques were optimized for use on gold surfaces both separately and as part of surface plasmon resonance (SPR) sensor chips. The population of carboxylic acid functional groups as binding sites in the polymer matrix, as reflected in the corresponding hydrophilicity, could be easily adjusted through changes to the stoichiometric ratio of the monomers, allowing for good control of immobilization capacity. The polymers used adhered to the gold surfaces both with and without use of thiol moieties. Coating thickness was measured by ellipsometry and coatings of 30–40 nm thickness were routinely achieved on gold-coated slides. This dimension is dependent on the spin speed and the viscosity of the polymerization mixture applied. The polymers were further characterized by contact angle measurements and infrared spectroscopy before being applied to immobilization of the steroid cortisol in a BIAcore SPR instrument, where binding to a monoclonal antibody was studied and the surface coatings optimized for maximum specific binding capacity. Optimized surfaces could be regenerated and re-used, and have potential applications as immobilization matrices in plasmonic biosensors with a very rapid coating technique.     

Effect of different electrolytes on the swelling properties of calyx[4]pyrrole-containing polyacrylamide membranes

Calix[4]pyrrole (1) was synthesized and characterized and this macrocycle was incorporated in polyacrylamide gels. The presence of meso-octamethyl-porphyrinogen inside of gel was checked using infrared spectroscopy, differential scanning calorimetry, and swelling studies. The swelling degree of these hydrogels in equilibrium with different electrolytes (NaCl, LiCl, KCl, CaCl₂ and AlCl₃) was measured in a concentration range 0.1-0.5 mol dm⁻³. Although no significant alterations in the swelling degree can be found for the different 1:1 electrolytes, when the cation charge of unsymmetrical electrolytes increases, the gel swells in a significant way. This swelling process is enhanced by the presence of calyx[4]pyrrole. The effect of alkaline hydrolysis of polaycrylamide-based hydrogels was also studied. The hydrolysed hydrogels collapse in the presence of the electrolytes; this behavior is dependent on the hydrolysis degree, electrolyte charge and calyx[4]pyrrole presence and concentration; the latter leads to polyacrylamide with tailor-made properties.     

Adhesion of Yersinia ruckeri to fish farm materials: influence of cell and material surface properties

Two strains (an environmental strain and a reference one coming from a national culture collection) of Yersinia ruckeri, a fish pathogenic bacterium, are characterised according to the ability to adhere on wood, concrete, polyvinylchloride (PVC) and fibreglass, four materials commonly found in fish farms. The relationships between adherence, bacterial and support hydrophobicities and surface roughness are investigated. The results show that: (i) Y. ruckeri is strongly hydrophilic; (ii) the environmental strain exhibits a higher ability to adhere than the reference one; and (iii) for the two strains a strong correlation is observed between roughness amplitude (RA) of the support material and adhesion ability.     

The surface energy of kaolinite

The surface energy of kaolinite was determined from the water adsorption isotherm, the water/kaolinite contact angle, and the surface tension of water, using a formula obtained by combining the Young equation with the general equation of pair interaction. This formula could be represented by a polynomial function whose roots gave one real value of 252.57±2.75 mJ m^–2 for the surface energy of kaolinite. An important feature of the procedure for obtaining this energy is the use of the Young equation to determine the range in which the value of the surface energy lies.     

Nano-sized Co(II)-8-hydroxyquinolate complex thin film via surface layer-by-layer chemical deposition method: Optimized factors and optical properties

An extensive study was performed and reported for evaluation and optimization of the factors affecting thin film formation of nano-sized Co(II)-8-hydroxyquinolate complex by surface layer-by-layer chemical deposition method. The formation of uniform thin films of nano-crystalline metal complex is heavily dependent on several important factors. Variation in metal and ligand concentrations (1:1–1:3) was found to show insignificant contribution to the molar stoichiometric ratio of the synthesized thin film of nano-sized Co(II)-8-hydroxyquinolate. The number of dipping cycles (2–50) was characterized by strong influence on the thin film thickness. The dependence of the immersion time (2–50 s) was proved to influence the crystal growth and homogeneity of the thin film. The role of pH of metal and ligand solutions was identified by strong contribution in development and formation of deposited Co(II)-8-hydroxyquinolate complex thin film. Finally, the role of solvent on the thin film formation was also studied and evaluated. Metal analysis, SEM, EI-MS, FT-IR and TGA were applied as monitoring techniques of these factors. The optical properties of Co(II)-8-hydroxyquinolate complex were also studied and the complex thin films were characterized by the highest optical transition from π–π* or n, π* states with energy gap in the UV-range at 3.13 eV. The lowest optical transition resulted from d–d transition or metal centered transition with energy 1.5 eV while, the optical transition at 2.35 eV is the contribution of metal ligand or ligand metal transition. In the light of the optical measurement, Co(II)-8-hydroxyquinolate complex can be considered as an organic semiconductor with the potential applications in the design of organic light-emitting diodes (OLEMs).     

Effects of Co-addition of DBS and PEG on Wetting Performance of TiO_2 Film

Nanocrystalline anatase TiO2 films with indium tin oxide(ITO) coated glass as the film substrate were fabricated through spin-coating technique. The TiO2 pastes were prepared with sodium dodecylbenzenesulfonate(DBS) modified TiO2 nanocrystals, synthesized by sol-hydrothermal processes in advance, together with different amounts of polyethylene glycol(PEG) macromolecules. The as-prepared films were mainly characterized by ultraviolet-visible (UV-Vis) spectroscopy, field emission scanning electron microscopy(...     

衬底温度对全氟取代酞菁锌固体薄膜微结构的影响

用UV-Vis光谱、X射线衍射(XRD)和原子力显微镜(AFM)对全氟取代酞菁锌(F₁₆PcZn)在不同温度下的石英衬底上的分子堆砌方式进行了研究,F₁₆PcZn分子沉积按3个阶段进行.首先通过F^-原子与石英衬底的强相互作用形成“card-packing”奠基层,进而形成“amorphousaccumulation”过渡层,最后形成有序的“brick-stacking”结晶层.三种分子堆砌方式对应的吸收光谱谱峰分别出现在640,670和810nm附近.810nm附近吸收峰形状的变化说明衬底温度升高有利于“brick-stacking”堆砌方式的实现,AFM观察的结果证实衬底温度升高使结晶微畴增大.常温下结晶层中分子以单斜点阵平行排列,点阵常数a为1.494nm,在250～300℃下分子发生位型微调,F₁₆PcZn分子采取更致密的堆积方式(a=1.428nm).