Water-repellent acylated and silylated wood samples and their surface analytical characterization

The interest for chemical modification of wood with the aim of preserving it from physical and biochemical deterioration is rapidly increasing. Among the possibilities, acetylation has a great potential for improving the dimension instability of wood against moisture and the durability of wooden objects. Recently, a new acetylating agent, isopropenyl acetate has attracted attention giving an improved acetylating method. By increasing the size of the acyl group, a positive effect on the wood hydrophobicity can be reached. The anhydrides, however, are less reactive. Another applicable surface modification is the silylation of wood that renders the wood surface hydrophobic.

In this paper, we report about the acylation and silylation of different wood samples. A new manufacturing process is tested in which low-value Eucalyptus wood is mixed acylated. The reagent mixture contains at least two kinds of acyl group. One of them is acetyl group; the other(s) can be user-defined. We also report about a silylation method, in which catalyst facilitates the chemisorption process. The extent of modification of the treated wood samples was evaluated by means of weight percent gain, ATR-FTIR, and pyrolysis-gas chromatography–mass spectrometry (Py-GC/MS). Methylene blue adsorption of selected samples was also studied. The result of analytical measurements was in agreement with that of wettability studies.     

导电高分子材料浸润性的研究进展

综述了具有不同浸润性的导电高分子材料在制备和性质研究方面的工作进展.根据功能化阶段的不同,从聚合过程、氧化还原过程、后处理过程以及氟化处理过程等四个方面对导电高分子材料浸润性功能化的研究方法进行了比较详尽的综述.在此基础上,简单对比了国内、外的发展情况,并展望了该研究方向的研究前景.     

CTAB在硅胶表面吸附引起的润湿性变化和模拟驱油

用椭圆偏振法测定溴代十六烷基三甲胺（CTAB）水溶液在光滑的二氧化硅膜片上的吸附，其结果符合两阶段模型，即在不同浓度下发生单分子层和近似双分子层的吸附，并与其表面润湿性变化的数据吻合.用改进的Washburn方程测量改性硅胶粉末的润湿性, 研究了CTAB水溶液在硅胶粉末表面上吸附引起的润湿性变化.并由此探讨了CTAB水溶液在硅胶粉末表面的润湿性,表面活性剂的临界胶束浓度（CMC）与表面含油粉末脱油率的关系，对在非超低界面张力条件下通过改变固/液界面润湿性提高原油采收率作了实验探讨.     

Reversible Wettability of Tungsten Trioxide Films with Novel Dandelion‐like Structures

Tungsten trioxide (WO₃) films with novel dandelion‐like structures were prepared by spin‐coating a sol of WO₃ with CTAB (cetyltrimethyl ammonium bromides) on quartz substrates. The resultant WO₃ films were characterized by X‐ray diffraction (XRD), FT‐IR spectroscopy, scanning electron microscopy (SEM), and X‐ray photoelectron spectroscopy (XPS). The wettabilities of the WO₃ films were evaluated by contact angle (CA) measurements. It was found that the WO₃ film exhibited superhydrophilicity under UV light irradiation, whereas after storage in the dark for a certain time, it turned to be superhydrophobic.     

Nanoparticles assembly-induced special wettability for bio-inspired materials

Through billions of years of evolution, nature has optimized the programmed assembly of the nano- and micro-scale structures of biological materials. Nanoparticle assembly provides an avenue for mimicking these multiscale functional structures. Bio-inspired surfaces with special wettability have attracted much attention for both fundamental research and practical applications. In this review, we focus on recent progress in nanoparticle assembly-induced special wettability, including superhydrophilic surfaces, superhydrophobic surfaces, superamphiphobic surfaces, stimuli-responsive surfaces, and self-healing surfaces. A brief summary and an outlook of the future of this research field are also provided.     

Investigating wettability alteration due to asphaltene precipitation: Imprints in surface multifractal characteristics

In the present study, multifractality and its formalism were employed to investigate the surface characteristics of an asphaltene deposited heterogeneous solid surface. Wettability alteration of the solid surface was found to affect the multifractal characteristics of an asphaltene deposited heterogeneous surface. Multifractal spectra f(α) show that the more oil wet the surface, the wider the spectrum, and the higher the f_max. The notable distinction between the multifractal spectra associated with different surface wettabilities can be used as a new aspect of wettability alteration.     

Effect of various treatment and glazing (coating) techniques on the roughness and wettability of ceramic dental restorative surfaces

Surface treatment procedures such as grinding and polishing are needed to provide the ceramic dental restorative materials with proper fitting and occlusion. The treated surfaces are customarily glazed to improve the strength and smoothness. Though smoothness and wetting of the dental surfaces are important to minimize bacterial plaque retention, influence of the surface treatment and glazing procedures on the final surface roughness and its correlation to wettability are overlooked.

In this work, effect of various treatment (diamond fraising, stoning, sanding and aluminum oxide and rubber polishing) and glazing (auto and overglazing) techniques on the final roughness and the resulting wettability of dental ceramic surfaces were investigated using scanning electron microscopy (SEM) observations and atomic force microscopy (AFM) scans, 75 scans per sample. The surfaces were characterized and assigned an average roughness measure, R_a. The wettability of the same surfaces was evaluated using micro-contact angle measurements (25 micro-bubbles placed on a grid on each surface) to correlate the final surface roughness and wettability.

The results show that overglazing prevails over surface irregularities from different treatment procedures and provides homegeneously smooth surfaces with mean R_a < 10 nm. It also produces uniformly wetted surfaces with low contact angles around 20°. The autoglazed surfaces are less smooth (mean R_a around 50 nm) and displays sporadic topographic irregularities. They display larger and less uniform contact angles ranging between 35° and 50°. The results suggest that overglazing should be preferred after surface treatment to obtain a smooth and well-wetted dental ceramic surface.     

Wettability of tri-block copolymer coated hydrophobic surfaces Predictions and measurements

Hydrophobic surfaces with adsorbed tri-block copolymers are wetted by oil in spite of the hydrophilic buoy groups of the block copolymer that are present near the surface. The effect of the buoy group length of the adsorbed molecules on the wettability of hydrophobic surfaces is studied by contact angle measurements and by computer modelling.

The computer model predicts an increase in interfacial free energy with increasing buoy group length for equilibrium adsorption of block copolymer from water. Molecules with large buoy groups occupy more lateral space; therefore the “bare” surface gets more exposed and the anchor groups contribute less to the interfacial free energy which thus increases with the buoy group length.

The calculations showed that the variation of the interaction parameter between solvent and buoy group hardly influences the interfacial free energy. In contrast the interaction parameter between solvent and surface influences the interfacial free energy to a large extent because the oil/surface interactions have a lower energetic value as compared to water/surface interactions and therefore the interfacial free energy is lower than in water. The interfacial free energy varies slightly with increasing buoy group length, depending on the value chosen for the solvent/surface interaction parameter.

Advancing and receding contact angles of hexadecane, sunflower oil and hydrolysate (partly hydrolysed sunflower oil) were measured on hydrophobic surfaces. All oil/water contact angles were small, indicating a hydrophobic apolar surface character. It was found that, for oils with a “good” interaction with the surface (hexadecane and sunflower oil), the contact angle has a minimum value at a certain buoy group length. For hydrolysate (less-strong interaction with the surface) the contact angle decreases monotonically with increasing buoy group length. The results for hexadecane, sunflower oil and hydrolysate are in reasonable agreement with the model predictions. The effect of increasing buoy group length is weak; both decreasing and increasing angles are found, depending on the type of oil used.     

Evolution of wood surface free energy after heat treatment

Surface free energies of pine and beech wood were investigated before and after heat treatment using the Lifshitz-van der Waals/acid-base approach from contact angles measured by the Wilhelmy method. The results obtained showed that the decrease of the electron-donating component of the acid-base component was the major parameter affecting the wetting of the modified wood's surface. The Lifshitz-van der Waals component was slightly modified after heat treatment indicating that the atomic and molecular interactions due to permanent or induced dipoles between wood macromolecules were weakly modified. Modification of the surface chemical composition was studied by X-ray photoelectron spectroscopy (XPS) and titration of acidity. XPS indicated an important decrease of the O/C ratio after heat treatment explaining the decrease of the electron-donating component (γ⁻) of the surface free energy. The decarboxylation and degradation of glucuronic acids present in hemicelluloses, demonstrated by titration of carboxylic acid functions of wood, had only limited effect on the electron-accepting component (γ⁺).     

Experimental displacement patterns in a 2 × 2 quadrant block with permeability and wettability heterogeneities—problems for numerical modelling

The effect of heterogeneities on miscible and immiscible flood displacements in 2D bead packs in quadrant form, 2 × 2 block heterogeneity, with either a permeability or a wettability contrast is the subject of this paper. The physical processes occurring during miscible and immiscible flow and displacement within permeability and wettability quadrant bead pack models have been studied experimentally. This geometry occurs in a number of situations relevant to hydrocarbon production: particularly faults where adjacent rocks have large permeability contrasts with rapid changes, in the laboratory with core butting, in reservoir simulation where grid blocks have different permeability and in reservoirs having near-wellbore damage problems. The model quadrants 1–4, had 1 and 4 and 2 and 3 with identical properties, either in permeability or wettability. Reported are complete unit mobility miscible displacements, then the effects of viscosity differences (mobility modifiers) and finally immiscible displacements on displacement patterns for initial linear injection. The experiments demonstrate that nodal flow occurs for both miscible and immiscible flow, but for immiscible flow there are boundary effects due to capillary pressure differences created by water saturation changes or wettability contrasts which can leave patches of isolated fluid within a quadrant. The displacement patterns for the different models and fluids change significantly with the viscosity and wettability changes, particularly for the immiscible displacements. This is due to the changing capillary pressure between the quadrant blocks as the water saturation change. These are difficult to address in numerical modelling but should be accounted for. Other effects include coupling of all physical processes governing the flow through the node and creations of microzones of trapped residual oil. Our displacement patterns can therefore be a valuable verification benchmark tool for numerical modelling and a calibration data source for those wishing to simulate the effects of capillary pressure under differing wettability conditions and for those investigating upscaling modelling procedures. However, the possible loss of physical reality when averaging must always be considered.