Two kinds of composite films: Graphene oxide/carbon nanotube film and graphene oxide/activated carbon film via a self-assemble preparation process

Two kinds of free-standing composite films, including graphene oxide and activated carbon film as well as graphene oxide and carbon nanotube film, were fabricated through a simple suspension mixing and then natural deposition process. The films were characterized by various measurement techniques in detail. The results show that the composite films without any treatment almost still remain the original properties of the corresponding precursors, and exhibit loose structure, which can be easily broken in water; whereas after treated at 200 °C in air, the films become relatively more dense, and even if immersed into concentrated strong alkali or acid for five days, they still keep the film-morphologies, but regretfully, they show obvious brittleness and slight hydrophilicity. As soon as the treated films are performed in high concentrated strong alkali for about one day, their brittleness and wettability can be improved and became good flexibility and complete hydrophilicity.     

The wettability and interfacial characterization between γ-TiAl alloy and ceramic reinforcements

The wettability and interfacial characterization of γ-TiAl alloy on TiC_0.78, TiN_0.87, and VNx substrates were studied using the Sessile Drop method at 1758 K. The equilibrium apparent contact angle of liquid γ-TiAl alloy are 8° on TiC_0.78 substrate, 22° on TiN_0.87, but deficient for VNx substrate because of the gradual appearance of solidification phenomena. The spreading mechanism of γ-TiAl/TiC_0.78 was ascribed to the product control model, which was determined by the new Ti₂AlC formed at the interface. The decreased apparent contact angle of γ-TiAl on TiN_0.87 substrate with the slow rate resulted from the combined effect of Ti adsorption at the interface and the decreased surface tension and viscosity of the liquid. The γ-TiAl/VNx system was a dissolution system. The effect of dissolution on apparent contact angle is reflected in the initial stage and progressed synchronously with the movement of the triple-phase line.     

Surface properties of CTMP fibers modified with xylans

This study investigated the effect of modification with xylan on the surface properties of chemithermomechanical pulp (CTMP) from spruce. The surface modifications were carried out by controlled sorption of birch xylan from solution at high temperature and high pH. Several different analysis techniques were used to study the effects on fiber surface composition and morphology. The ESCA technique showed a reduction in the amount of carbons not bound to oxygen in the C(1s) resolved peak after treatment. Variations in surface topography between untreated samples and samples with xylan were studied with SEM and AFM in the tapping mode. Scanning electron micrographs show micrometersized xylan particle structures spread over the fiber surfaces. AFM images reveal differences in the fine structure of fibers. The modified fibers exhibit a nanometersized, bumplike morphology not seen on the untreated fibers. The wetting properties of single fibers were determined with the Wilhelmy plate technique and the water sorption of CTMP paper sheets was studied using a dynamic contactangle tester. The surface modification of CTMP with xylan significantly decreased the advancing contact angle of single fibers and also improved the water sorption of sheets.     

Thin-layer chromatographic and high-performance thin-layer chromatographic ready-for-use layers with lipophilic modifications

Stable silica gel sorbents with aliphatic or aromatic groups are formed by chemical modifications of the silanol groups with special reactive silanes. Various lipophilic surface modifications on silica gels with varying pore structures are tested with regard to their chemical and physico-chemical characteristics, their wettability and their chromatographic retention data. The main problem in TLC is the preparation of abrasion-resistant layers on glass or on foils which meet the usual high standard of quality and are also suited for quantitative determinations. Thin-layer chromatography on reversed-phase layers can only be performed if the complete wettability of the lipophilic stationary phase in dry form is guaranteed by the mobile phase. Adsorption-chromatographic separations with lipophilic eluents and reversed-phase partition-chromatographic separations with hydrophilic eluents are performed, for example, with dyes, with polycyclic aromatic hydrocarbons and with lipids. The great differences in selectivity caused by the various modifications of the sorbent and the varying eluent composition are remarkable. Ready-for-use layers with lipophilic surface modifications complement the existing range of pre-coated layers and thus widen the application of TLC and HPTLC considerably.     

微/纳米结构的聚苯胺及其浸润性研究

借助沉积聚合辅助的“无模板”法在玻璃基片上制备出水杨酸掺杂的微/纳米结构的聚苯胺.实验发现,微/纳米结构的形貌及其浸润性依赖于掺杂剂与单体的摩尔比和沉积时间.当低分子量的聚苯胺微米球和纳米球共存时,其沉积的表面呈现出高的疏水性(接触角θ=148.0°),这主要来源于微/纳米共存的结构导致高的表面粗糙度,能捕获更多的空气所致.FTIR,紫外-可见光谱和X光射线衍射表征了微/纳米球的分子结构及其结晶性.     

蚊子体表面的微纳米结构与浸润性

通过光学显微镜及自行设计的接触角测试系统研究了成蚊体表面(如翅膀、 复眼)的浸润行为, 发现了不同的体表面由于不同的生物功能而具有不同的超疏水特性. 通过扫描电子显微镜检测成蚊翅膀和复眼表面, 揭示了分布在成蚊体表面上的不同的微观结构形貌, 另外, 微米结构表面上还包含了纳米结构是其体表面微观结构的共同属性. 因此, 微纳米等级结构与浸润性之间存在重要的依赖关系.     

A thermoreversible double gel: characterization of a methylcellulose and kappa-carrageenan mixed system in water by SAXS, DSC and rheology

Sol-gel and gel-sol thermal transition of methylcellulose/water, kappa-carrageenan/water and methylcellulose/kappa-carrageenan/water mixtures was investigated utilizing small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC) and oscillatory rheological experiments in temperature regime from 20 to 80 degrees C. Methylcellulose (E461) and kappa-carrageenan (E407) are well-known additives used for gelation in various nutrition and other products. The formulation and characterization of a mixed thermoreversible methylcellulose/kappa-carrageenan/water gel with very interesting double thermal transition gel-sol-gel upon heating was possible. This specific thermal behavior provides a liquid state of the system between the low-temperature and high-temperature gel-state and at the same time allows for the easy temperature tuning of the system's state. As such this system is suggested to be further tested as potential carrier for various functional colloidal systems.     

Wettability and osteoblast cell response modulation through UV laser processing of nylon 6,6

With an ageing population the demand for cheap, efficient implants is ever increasing. Laser surface treatment offers a unique means of varying biomimetic properties to determine generic parameters to predict cell responses. This paper details how a KrF excimer laser can be employed for both laser-induced patterning and whole area irradiative processing to modulate the wettability characteristics and osteoblast cell response following 24 h and 4 day incubation. Through white light interferometry (WLI) it was found that the surface roughness had considerably increased by up to 1.5 μm for the laser-induced patterned samples and remained somewhat constant at around 0.1 μm for the whole area irradiative processed samples. A sessile drop device determined that the wettability characteristics differed between the surface treatments. For the patterned samples the contact angle, θ, increased by up to 25° which can be attributed to a mixed-state wetting regime. For the whole area irradiative processed samples θ decreased owed to an increase in polar component, γ^P. For all samples θ was a decreasing function of the surface energy. The laser whole area irradiative processed samples gave rise to a distinct correlative trend between the cell response, θ and γ^P. However, no strong relationship was determined for the laser-induced patterned samples due to the mixed-state wetting regime. As a result, owed to the relationships and evidence of cell differentiation one can deduce that laser whole area irradiative processing is an attractive technology for employment within regenerative medicine to meet the demands of an ageing population.     

Estimating critical surface tension from droplet spreading area

Critical surface tension (CST) is a measure of solid surface tension and is mainly determined by measuring the contact angle of a droplet on a target solid surface. The concept of CST makes it possible to determine solid surface tension without any unprovable assumptions such as the Fowkes hypothesis. However, it requires somewhat special devices and skills for measuring the contact angle. In this work, we propose a simple method to determine the CST of a solid by measuring the droplet spreading area. This method is developed by combining the conventional CST with a simple analytical droplet model. The difference in estimated CSTs between our method and the conventional one is within 3.0%. Our method enables a quick and simple evaluation of the solid surface tension without special devices for measuring the contact angle.