A novel method to fabricate water-soluble hydrophobic agent and super-hydrophobic film on pretreated metals

This paper demonstrated a convenient method to prepare water-soluble hydrophobic agent and create super-hydrophobic film on the basic material of phosphating film and electroless Ni-P composite coating on carbon steels. Water contact angles and rolling angles of super-hydrophobic films were 155-168° and 2-3° on phosphating films, respectively, 145-155° and 15-20° on electroless Ni-P composite coatings, respectively. This water-soluble hydrophobic agent was white latex and had lots of micro-particles suspending in it. The thickness of the single-layer super-hydrophobic film with good corrosion resistance and stability was about 2-3 μm. The microstructure of super-hydrophobic film was discussed using XRD, EDS, optical and electronic microscope as analytical methods. This kind of super-hydrophobic film had a great many micro-particles dispersing in the surface, which contained F and Si and greatly increased the roughness of the surface.     

RF-PACVD of water repellent and protective HMDSO coatings on bell metal surfaces: Correlation between discharge parameters and film properties

Hexamethyldisiloxane (HMDSO) films have been deposited on bell metal using radiofrequency plasma assisted chemical vapor deposition (RF-PACVD) technique. The protective performances of the HMDSO films and their water repellency have been investigated as a function of DC self-bias voltage on the substrates during deposition. Plasma potential measurements during film deposition process are carried out by self-compensated emissive probe. Optical emission spectroscopy (OES) analyses of the plasma during deposition reveal no significant change in the plasma composition within the DC self-bias voltage range of −40 V to −160 V that is used. Raman and X-ray photoelectron spectroscopy (XPS) studies are carried out for film chemistry analysis and indicate that the impinging ion energy on the substrates influences the physio-chemical properties of the HMDSO films. At critical ion energy of 113 qV (corresponding to DC self-bias voltage of −100 V), the deposited HMDSO film exhibits least defective Si-O-Si chemical structure and highest inorganic character and this contributes to its best corrosion resistance behavior. The hardness and elastic modulus of the films are found to be bias dependent and are 1.27 GPa and 5.36 GPa for films deposited at −100 V. The critical load for delamination is also bias dependent and is 11 mN for this film. The water repellency of the HMDSO films is observed to be dependent on the variation in surface roughness. The results of the investigations suggest that HMDSO films deposited by RF-PACVD can be used as protective coatings on bell metal surfaces.     

Hydrophobization of cotton fabric by Gliding Arc plasma discharge

The surface modification in order to obtain hydrophobic cotton fabrics was carried out using air/HMDSO Gliding Arc plasma discharge. The dependence of the surface wettability on used process parameters, such as air flow, sample distance and treatment time were investigated. The wettability of cotton fabrics was evaluated by the drop test method by measuring the time of droplet absorption and water contact angle (WCA). The changes in the surface morphology were examined by optical microscopy and scanning electron microscopy (SEM). The treated hydrophobic fabrics were subjected to the analysis of chemical composition of the applied coatings using the ATR-FTIR spectroscopy. Hydrophobic cotton fabrics were obtained, especially with a high resistance to static wetting. In addition, the treated cotton fabrics were tested using a spray test measurement and were subjected to multiple washing.     

Modification of polyethylene powder with an organic precursor in a spiral conveyor by hollow cathode glow discharge

Hexamethyldisiloxane (HMDSO) films were deposited on polyethylene (PE, (C₂H₄)_n) powder by hollow cathode glow discharge. The reactive species in different HMDSO/Ar plasmas were studied by optical emission spectroscopy (OES). Increasing the HMDSO fraction in the gas mixture additional compounds like CH_x, OH, SiC and SiO can be identified. After deposition the formed silicon and carbon containing groups (C–O, C=O, SiC and SiO) on the PE powder surface have been analyzed by X-ray photoemission spectroscopy (XPS). Changes in wettability depending on the HMDSO fraction were investigated by contact angle measurements (CAM). The free surface energy of the PE powder decreases with increasing HMDSO fraction in the process gas and encapsulation of the powder particles occurs. An aging effect of the plasma treated PE surface was observed depending on the process gas composition. The higher the HMDSO fraction the less is the aging effect of the plasma treated PE surface.     

Easy fabrication of large-size superhydrophobic surfaces by atmospheric pressure plasma polymerization with non-polar aromatic hydrocarbon in an in-line process

We report on the formation of superhydrophobic surfaces on glass by plasma polymerization with non-polar aromatic hydrocarbon, at atmospheric pressure, in an in-line process. The glass was simply treated by radio frequency (RF) plasma with a mixture of toluene and hexamethyldisiloxane (HMDSO). The hydrophobicity of the sample surfaces increase with increasing plasma treatments; contact angles of 150° for water droplets are achieved. It is attributed mainly to its high content of non-polar hydrophobic phenyl groups and its rough surface.     

The friction property of super-hydrophobic cotton textiles

Two kinds of super-hydrophobic cotton textiles were prepared via dip-coating cotton textiles with nano-silica suspensions, and the cotton textiles exhibits high contact angle more than 160° and low sliding angle lower than 4°. A friction method was used to evaluate the durability of the as-prepared super-hydrophobic cotton textiles, the results shows that one of the as-prepared super-hydrophobic cottons exhibits better stability property against friction, and its contact angle remained higher than 150° and sliding angle remained lower than 15° after 1000 times friction. SEM analysis shows the reduction of hydrophobic property was resulted from the damage of surface structure during friction cycle.     

AFM and contact angle investigation of growth and structure of pp-HMDSO thin films

HMDSO was plasma polymerized on silicon wafer and polyethylene (PE) substrates. The chemical structure of the pp-HMDSO was analyzed with Fourier-transform infrared (FT-IR) spectroscopy. The morphological structure of the thin films deposited on the different substrates was investigated by means of atomic force microscopy (AFM), indicating different coverage mechanisms. In order to investigate the growth process of the pp-HMDSO, films of different thickness were also deposited, varying the plasma deposition time from 10 s to 1800 s. Thickness and structure of such deposits was detected with AFM. Finally, hydrophobic characteristics of the different samples were evaluated by means of contact angle measurements and correlated with the morphological characteristics.     

Study of glucose oxidase–l-α-lecithin Langmuir film formation on air–water interface

The present paper describes the formation of glucose oxidase (GOx)–l-α-lecithin Langmuir film on air–water interface by spreading GOx solution directly onto subphase covered with layer of lecithin. The optimum experiment conditions were obtained according to the experimental results. Two phase transition processes were observed under surface pressure ranges of 8.0–11.0 mN/m and 15.0–30.0 mN/m, which represented the movement of GOx molecules under the lecithin layer and the reorientation of GOx molecules in the lecithin layer and/or expulsion of GOx molecules from the lecithin layer, respectively. The forces of GOx molecules that interacted with the lecithin layer were hydrogen bonding and hydrophobic force. An atomic force microscopy image of GOx–lecithin film deposited on Au (1 1 1) surface in optimal conditions gives evidence of well-ordered GOx molecules in the lecithin layer. As a target of this research, this work provides a new way to prepare biomimetic film and design glucose biosensors in future.     

Super-hydrophobic nickel films with micro-nano hierarchical structure prepared by electrodeposition

Super-hydrophobic nickel films were prepared by a simple and low cost electrodepositing method. The surface morphologies of the films characterized by scanning electronic microscope exhibit hierarchical structure with micro-nanocones array, which can be responsible for their super-hydrophobic characteristic (water contact angle over 150°) without chemical modification. The wettability of the film can be varied from super-hydrophobic (water contact angle 154°) to relatively hydrophilic (water contact angle 87°) by controlling the size of the micro-nanocones. The mechanism of the hydrophobic characteristic of nickel films with this unique structure was illustrated by several models. Such micro-nanostructure and its special wettability are expected to be applied in the practical industry.     

Applicability of the polyimide films as an SSNTD material

Track registration properties in polyimide films, KAPTON, for heavy ions have been examined by means of FT-IR spectrometry and the chemical etching in sodium hypochlorite solution. The effective track core size for the loss of CO and C–N–C composing imide bonds, and diphenyl ethers of C–O–C have been evaluated under the irradiations by Ne, Fe and Xe ions at energies less than 6 MeV/n. On the other hand, the etching property of the polyimide films has been examined in the sodium hypochlorite solution at temperature of 55 °C. Before the etchings, the films were exposed to H, C, Ne, Fe and Xe ions, at incident energies below 6 MeV/n. The etch pits are found only on the films exposed to Fe and Xe ions, indicating significant difference on the etch pit size between them. This implies that the polyimide film has charge or energy resolution for these relatively heavy ions. The threshold level of the etchable track registration is inferred to be around 2500 keV/μm. The effective track core radius at this stopping power for the loss of diphenyl ether is 1.6 nm, which is equivalent to the length between the adjacent diphenyl ether bonds in the polyimide chains. Breakings at two adjacent diphenyl ethers in radial direction of latent tracks may produce etchable tracks in KAPTON.     

Fabrication and structural characterization of nanocomposites consisting of Ni nanoparticles dispersed in polyimide films

Formation and structure of composite layer consisting of polyimide films containing Ni nanoparticles were investigated. The preparation method relies on KOH treatment on polyimide film to form carboxyl acid groups and adsorption of Ni ions by ion exchange followed by hydrogen reduction. The amount of Ni ions adsorbed in polyimide films were found to be systematically controlled by changing initial KOH concentration, subsequent ion exchange time, pH and temperature. Cross-sectional TEM observation revealed that Ni nanoparticles with 3-5 nm in diameter were homogeneously dispersed in the surface modified polyimide layer after heat treatment above 250 ^°C in H₂ atmosphere. The size and distribution of the Ni nanoparticles were strongly dependent on the heat treatment temperature, indicating that this method allows microstructural tuning of metal/polymer nanocomposites.     

Absorption Spectral Study of Mixed Chiral Amino Acid Porphyrin Langmuir-Blodgett Films

Absorption spectra were performed on Langmuir-Blodgett films of a new chiral amino acid porphyrin (Py) and its mixture with stearic acid (SA). Vertical uniformity of the LB films has been demonstrated by the linear relationship between the absorbance and the layer number of films. J-Aggregates were present when the film was transferred at various surface pressures and at different molar ratios of Py and SA. However, no aggregation was present for the molecules in the adjacent monolayers. the observed optical absorption spectra of mixed films were markedly dependent on the combination of Py. When the molar ratio of Py was increased from 0.05 to 0.75, the absorption peaks of Soret and Q bands bathochromically shifted ca. 5.5 and 2.2 nm. When the deposited pressure was increased from 5 to 35 mN/m, the absorption peaks of Soret and Q bands bathochromically shifted ca. 3.7, 3.2 nm and 3.5, 2.2 nm for pure Py and 1:3 Py-SA mixed LB films, respectively. on a hydrophobic substrate, the LB films showed a red shift of ca. 4.5 nm for Soret band compared with that on the hydrophilic substrate owing to their different environments.     

Characterization of stable hydrophobic carbon coating and its application in removing organic pollutants

Polydimethylsiloxane (PDMS) thin films were deposited on Ni particles with a mean size of ～1 μm using chemical vapor deposition method. The thin films consisting of these PDMS-covered Ni particles showed a water contact angle higher than 160°, corresponding to the superhydrophobicity. These superhydrophobic films were found to be resistant toward acidic and basic media. The PDMS-covered Ni particles showed high affinity toward non-polar organic solvent such as toluene. Together with an external magnetic field, the PDMS-covered Ni can be used for separating water and toluene from a water/toluene heterogeneous mixture.     

LB膜的XPS光谱及其电致发光

采用X射线光电子能谱 (XPS)和UV Vis光谱研究了 2个以 8 氨基喹啉为亲水头基的两亲配体 ;2 长链烷基丙二酸二 (8 氨基喹啉 )酰胺 (H2 A) (H2 A1 2 :长链烷基为十二烷基 ;H2 A1 6 :十六烷基 )在气 /水界面与Cu2 离子的配位作用。配位后H2 A1 2 和H2 A1 6 单分子膜的崩溃压分别由 12 5和 15 6mN·m- 1 增加至 2 8 0和33 8mN·m- 1 。从含Cu2 离子亚相表面组装的LB膜出现了Cu2 离子的特征XPS峰 ,Cu2p为 935和 95 5eV ,XPS表明H2 A与Cu2 的配位比为 1∶1。H2 A的LB膜可以用作电致发光 (EL)器件的空穴传输材料 ,三层EL器件ITO/TPD/LB膜 /Alq3/Al(LB膜分别为 15层H2 A1 2 和 15层H2 A1 6 )的驱动电压分别为 6 5和 7 5V ,最大亮度分别为 6 2 1和 2 0 1cd·m- 2 。     

Preparation and tribological performance of perfluoropolyether derived coatings

A series of perfluoropolyether (PFPE) functional derivatives terminated with different amide groups (FD-As) were synthesized. The chemical structures of the FD-As were determined by FTIR, ¹H and ¹⁹F NMR spectra, and the thermo stability was determined by TG analysis. Thin films of FD-As were fabricated by strongly adsorbing FD-As molecules on the surfaces of metals such as aluminum plates and steel balls. The thin films of FD-As prepared possessed very low surface free energy about 12 mN/m. Tribological performance of these thin films was characterized using a UMT-2 model micro-tribometer and a four-ball tribotester using paraffin liquid as lubricant. Thin films of FD-As at both states of UMT and four-ball tribo analysis can reduce the friction coefficient. And the anti-wear property of the liquid lubricant can also be improved.     

Relaxation time of the topological T1 process in a two-dimensional foam

The elementary topological T1 process in a two-dimensional foam corresponds to the flip of one film with respect to the geometrical constraints, and is a process by which the structure of an out-of-equilibrium foam evolves. We study both experimentally and theoretically the T1 dynamics in a dry two-dimensional foam. The dynamics is controlled by the surface viscoelastic properties of the films (surface shear plus dilatational viscosity, mu_{s}+kappa, and Gibbs elasticity ), and is independent of the shear viscosity of the bulk liquid. Moreover, the dynamics of the T1 process provides a tool for measuring the surface rheological properties: we obtained =32+/-8 mN/m and mu_{s}+kappa=1.3+/-0.7 mPa.m.s for sodium dodecyl sulfate, and =65+/-12 mN/m and mu_{s}+kappa=31+/-12 mPa.m.s for bovine serum albumin, in good agreement with literature values.     

荧光标记十八胺LB膜的光谱研究

正十八胺以氯化丹酰和8-苯胺基-1-萘磺酸衍生化,单独或与硬脂酸混合后拉制成LB膜,并以稳态和时间分辨荧光研究了膜中分子的微环境和微结构等光物理性质.     

Short-time plasma surface modification of HDPE powder in a Plasma Downer Reactor - process, wettability improvement and ageing effects

The effectiveness of improving the wettability of HDPE powders within less than 0.1 s by plasma surface modification in a Plasma Downer Reactor is investigated. A correlation is revealed between the XPS results (O/C-ratio) and the wettability (contact angle, polar surface tension by capillary rise method). The O₂-content in the plasma feed gas has been adjusted for best wettability properties. XPS results indicate the formation of CO and COOH functional groups on the powder surface. The O/C-ratio increased from 0.0 (no oxygen on the non-treated powder) up to 0.15 for the plasma treated HDPE powder surface. With pure O₂-plasma treatment, a water contact angle reduction from >90° (no water penetration into the untreated PE powder) down to 65° was achieved. The total surface free energy increased from 31.2 to 45 mN/m. Ageing of treated powders occurs and proceeds mostly within the first 7 days of storage. Contact angle measurements and O1s/O2s intensity ratio data support that ageing is mainly a diffusion-controlled process. Nevertheless, XPS results show the presence of oxygen functional groups even after 40 days, which explains why the powder is still dispersible in water without any addition of surfactants.     

Fabrication and tribological properties of super-hydrophobic surfaces based on porous silicon

In the present work, super-hydrophobic surfaces based on porous silicon (PS) were constructed by the self-assembled molecular films and their tribological properties were investigated. A simple chemical etching approach was developed to fabricate PS with the certain rough microstructure surface, which can be observed by the environmental scanning electron microscopy (ESEM). The hydrocarbon and fluorocarbon alkylsilane molecular films were self-assembled on PS, which was confirmed by the X-ray photoelectron spectroscopy (XPS) measurement. In contrast to PS, the alkylsilane molecular films modified PS (mPS) were super-hydrophobic since the apparent water contact angle (CA) exceeded 160°. The tribological properties of PS and the mPS were investigated by a ball-on-disk tribometer during the processes of different sliding velocities and normal loads. The experimental results showed that the alkylsilane molecular films could decrease the friction coefficient. Due to the difference of chain structure and functional groups, the fluorinated alkylsilane films are better candidates for improving the hydrophobicity and lubricating characteristics of PS comparing to the non-fluorinated ones. The carbon chain length of alkylsilane molecules self-assembling on the Si or PS substrates could have little effects on the hydrophobic properties and the tribology performances.     

The preparation of lotus-like super-hydrophobic copper surfaces by electroplating

The preparation of super-hydrophobic metal surfaces had to combine rough structures and the surface modifications with low surface energy materials. Although there were different views on it, no experiment was done to prove it yet. In this paper, the structure of natural lotus leaf was observed and the lotus-like surfaces on hydrophilic copper substrates were fabricated via electroplating in large current density. These surfaces were super-hydrophobic without any chemical modification. The hydrophobic mechanism was analyzed. It is believed that this was a meta-stable state in Cassie model. As long as the surface structure was suitable, hydrophobic surface, even super-hydrophobic surface, could be got on hydrophilic substrate.