Enhancing hydrophilicity and protein resistance of silicone hydrogels by plasma induced grafting with hydrophilic polymers

<正>The hydrophilicity of silicone hydrogels used as soft corneal contact lens plays an important role in wearing comfort.In order to enhance hydrophilicity and protein resistance,silicone hydrogel membranes were modified by atmospheric pressure glow discharge plasma(APGDP) induced surface graft polymerization of N-vinyl pyrrolidone(NVP) and poly(oligoethylene glycol methyl ether methacrylate)(PEGMA) in this paper.XPS analysis demonstrated the success of graft polymerization of NVP and PEGMA onto the surface of silicone hydrogel membranes.The hydrophilicity of silicone hydrogels was characterized by the measurement of water contact angle(WCA).The result showed that NVP grafted silicone hydrogel has the WCA of about 68°and PEGMA grafted silicone hydrogel has the lowest WCA of about 62°,while the pristine silicone hydrogel is hydrophobic with the WCA of about 103°.Protein resistance of silicone hydrogels was investigated by the method of bicinchoninic acid assay using bovine serum albumin(BSA) as a model.It's found that the grafted silicone hydrogel has a significant improvement of protein resistance,and PEGMA grafting is more efficient for the reduction of protein adsorption than NVP grafting.The silicone hydrogel membranes grafted with NVP and PEGMA are good candidates of soft corneal contact lenses.     

Superhydrophobic surfaces using selected zinc oxide microrod growth on ink-jetted patterns

The synthesis and properties of superhydrophobic surfaces based on binary surface topography made of zinc oxide (ZnO) microrod-decorated micropatterns are reported. ZnO is intrinsically hydrophilic but can be utilized to create hydrophobic surfaces by creating artificial roughness via microstructuring. Micron scale patterns consisting of nanocrystalline ZnO seed particles were applied to glass substrates with a modified ink-jet printer. Microrods were then grown on the patterns by a hydrothermal process without any further chemical modification. Water contact angle (WCA)(1) up to 153° was achieved. Different micro array patterned surfaces with varying response of static contact angle or sessile droplet analysis are reported.     

Enhanced super-hydrophobic and switching behavior of ZnO nanostructured surfaces prepared by simple solution--immersion successive ionic layer adsorption and reaction process

A simple and cost-effective successive ionic layer adsorption and reaction (SILAR) method was adopted to fabricate hydrophobic ZnO nanostructured surfaces on transparent indium-tin oxide (ITO), glass and polyethylene terephthalate (PET) substrates. ZnO films deposited on different substrates show hierarchical structures like spindle, flower and spherical shape with diameters ranging from 30 to 300 nm. The photo-induced switching behaviors of ZnO film surfaces between hydrophobic and hydrophilic states were examined by water contact angle and X-ray photoelectron spectroscopy (XPS) analysis. ZnO nanostructured films had contact angles of ~140° and 160°±2 on glass and PET substrates, respectively, exhibiting hydrophobic behavior without any surface modification or treatment. Upon exposure to ultraviolet (UV) illumination, the films showed hydrophilic behavior (contact angle: 15°±2), which upon low thermal stimuli revert back to its original hydrophobic nature. Such reversible and repeatable switching behaviors were observed upon cyclical exposure to ultraviolet radiation. These biomimetic ZnO surfaces exhibit good anti-reflective properties with lower reflectance of 9% for PET substrates. Thus, the present work is significant in terms of its potential application in switching devices, solar coatings and self-cleaning smart windows.     

ICP刻蚀硅模板用于PDMS规则超疏水表面的制作

在ICP(inductively coupled plasma)刻蚀后的硅模板上复制聚二甲基硅氧烷(PDMS),经剥离得到含有一定尺寸的规则微柱阵列疏水表面.实验表明,当微柱高度较小时,微柱高度和边长对接触角有正影响,而间距则呈负影响;但如微柱高度较大,则高度对接触角的影响趋小,而边长呈负影响.间距对接触角的影响表现复杂.微柱间距6μm,边长14μm和高14μm微柱阵列的PDMS表面,静态接触角最大,约151°.     

Modification of the glass surface property in PDMS-glass hybrid microfluidic devices

This paper presents a simple method to change the hydrophilic nature of the glass surface in a poly(dimethylsiloxane) (PDMS)-glass hybrid microfluidic device to hydrophobic by an extra-heating step during the fabrication process. Glass substrates bonded to a native or oxygen plasma-treated PDMS chip having microchambers (12.5 mm diameter, 110 μm height) were heated at 200°C for 3 h, and then the hydrophobicity of the glass surfaces on the substrate was evaluated by measuring the contact angle of water. By the extra-heating process, the glass surfaces became hydrophobic, and its contact angle was around 109°, which is nearly the same as native PDMS surfaces. To demonstrate the usefulness of this surface modification method, a PDMS-glass hybrid microfluidic device equipped with microcapillary vent structures for pneumatic manipulation of droplets was fabricated. The feasibility of the microcapillary vent structures on the device with the hydrophobic glass surfaces are confirmed in practical use through leakage tests of the vent structures and liquid handling for the electrophoretic separation of DNA molecules.     

A facile method for preparing sticky, hydrophobic polymer surfaces

Textured surfaces consisting of nanometer- to micrometer-sized lightly sulfonated polystyrene ionomer (SPS) particles were prepared by rapid evaporation of the solvent from a dilute polymer solution-cast onto silica. The particle textured ionomer surfaces were prepared by either spin-coating or solution-casting ionomer solutions at controlled evaporation rates. The effects of the solvent used to spin-coat the film, the molecular weight of the ionomer, and the rate of solvent evaporation on the surface morphology of cast films were investigated. The surface morphologies were consistent with a spinodal decomposition mechanism, where the surface first existed as a percolated-like structure and then ripened into droplets if molecular mobility was retained for sufficient time. The SPS particles or particle aggregates were robust and resisted separation from the surface even after annealing at 120 °C for 1 week. The water contact angles on as-prepared surfaces were relatively low, ～90°, due to the polar groups in the ionomer, but when the surface was modified by chemical vapor deposition of 1H,1H,2H,2H-perfluorooctyltrichlorosilane, the surface contact angles increased to ～109° on smooth surfaces and up to ～140° on the textured surfaces. Although the surfaces were hydrophobic, the contact angle hysteresis was relatively high and water droplets stuck to these surfaces even when the surface was turned upside down.     

Enhancing the effect of the nanofiber network structure on thermoresponsive wettability switching

This letter reports the enhancing effects of a nanofiber network structure on stimuli-responsive wettability switching. Thermoresponsive coatings composed of nanofibers were prepared by electrospinning from thermoresponsive polymer poly(N-isopropylacrylamide) (PNIPAAm). The nanofiber coatings showed a large amplitude of thermoresponsive change in the wettability from hydrophilic to hydrophobic states compared to a smooth cast film. In particular, the combination of the surface chemistry and unique topology of the electrospun nanofiber coatings enables a transition from the Wenzel state to the metastable Cassie-Baxter state with an increase in temperature and consequently an enhanced amplitude of change in the water contact angles: the apparent contact angle differences between 25 and 50 °C are Δθ*(25-50?°C?)= 108 and 10° for the nanofiber coatings with a diameter of 830 nm and a smooth cast film, respectively. The fabrication of the 3D nanofiber network structure by electrospinning from stimuli-responsive materials is a promising option for highly responsive surfaces in wettability.     

Fabrication of highly transparent superhydrophobic coatings from hollow silica nanoparticles

We herein report a simple and effective method to fabricate excellent transparent superhydrophobic coatings. 3-Aminopropytriethoxysilane (APTS)-modified hollow silica nanoparticle sols were dip-coated on slide glasses, followed by thermal annealing and chemical vapor deposition with 1H,1H,2H,2H-perfluorooctyltrimethoxysilane (POTS). The largest water contact angle (WCA) of coating reached as high as 156° with a sliding angle (SA) of ≤2° and a maximum transmittance of 83.7%. The highest transmittance of coated slide glass reached as high as 92% with a WCA of 146° and an SA of ≤6°. A coating simultaneously showing both good transparency (90.2%) and superhydrophobicity (WCA: 150°, SA: 4°) was achieved through regulating the concentration of APTS and the withdrawing speed of dip-coating. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) were used to observe the morphology and structure of nanoparticles and coating surfaces. Optical properties were characterized by a UV-visible spectrophotometer. Surface wettability was studied by a contact angle/interface system. The effects of APTS concentration and the withdrawing speed of dip-coating were also discussed on the basis of experimental observations.     

On the respective effect of the surface energy and micro-geometry in the cleaning ability of bare and coated steels

It is aimed in this paper to assess the respective effect of surface energy and topography in the cleaning kinetics of soiled surfaces. Different flat and engraved stainless steels are characterized using contact angle measurements, topographic analysis and cleaning kinetics in presence of surfactants. Two coatings are also distinguished: silicon oxide (hydrophilic) and polysiloxane (hydrophobic).Except for the engraved surfaces, the determining parameter for the cleaning ability is the polar component of the surface energy: the larger this component, the better the cleaning performance. We proposed a simple model following which favorable interactions take between polar sites and the heads of surfactant. However, for engraved surfaces, the cleaning kinetics is strongly modified by some impregnation phenomena.     

Effect of deposition parameters on the wettability and microstructure of superhydrophobic films with hierarchical micro-nano structures

Superhydrophobic films with hierarchical micro-nano structures were deposited on glass substrates by solution immersion method from a solution containing cobalt chloride, urea and cetyl trimethyl ammonium bromide (CTAB). Subsequently the films were hydrophobized with a low surface energy material like octadecanoic acid under ambient conditions resulting in superhydrophobic surfaces with water contact angle (WCA) of about 168° and contact angle hysteresis of 1°. The effect of deposition parameters such as solution composition, temperature, deposition time and alkanoic acid treatment on surface morphology and wettability of the films was studied. Mechanism of formation of cobalt chloride carbonate hydroxide film is discussed. Addition of CTAB to the solution resulted in a change in the surface morphology of the deposited films with flower-like structures. The wettability of films obtained under different process conditions was correlated to surface roughness using Wenzel and Cassie models.     

pH响应性表面对蛋白质吸附的调控

通过表面引发原子转移自由基聚合在固定了引发剂的硅表面接枝了聚甲基丙烯酸叔丁酯(PtBMA),而后通过水解得到聚甲基丙烯酸(PMAA)聚合物刷.通过X射线光电子能谱、椭圆偏振仪和水接触角测试证明了接枝改性的成功.研究发现PMAA改性表面的浸润性和对蛋白质的吸附行为都具有一定的pH响应性.在较低pH值时改性表面相对疏水,随...     

Adsorption of PEO-PPO-PEO triblock copolymers with end-capped cationic chains of poly(2-dimethylaminoethyl methacrylate)

We study the adsorption of a symmetric triblock copolymer of ethylene oxide, EO, and propylene oxide, PO, end-capped with quarternized poly(2-dimethylaminoethyl methacrylate), DMAEMA (DMAEMA(24)-EO(132)PO(50)EO(132)-DMAEMA(24)). Light scattering and tensiometry are used to measure the relative size of the associated structures and surface excess at the air-liquid interface. The adsorbed amount, the amount of coupled water, and the viscoelasticity of the adsorbed polymer layer are measured on hydrophobic and hydrophilic surfaces (polypropylene, cellulose, and silica) by using quartz crystal microgravimetry (QCM) and surface plasmon resonance (SPR) at different ionic strengths and temperatures. The results of the experiments are compared with those obtained after adsorption of the uncharged precursor copolymer, without the cationic end-caps (EO(132)PO(50)EO(132)). DMAEMA(24)-EO(132)PO(50)EO(132)-DMAEMA(24) possesses higher affinity with the negatively charged silica and cellulose surfaces while the uncharged copolymer adsorbs to a larger extent on polypropylene surfaces. In this latter case, adsorption increases with increasing solution ionic strength and temperature. Adsorption of EO(132)PO(50)EO(132) on silica surfaces has little effect on the water contact angle (WCA), while adsorption of DMAEMA(24)-EO(132)PO(50)EO(132)-DMAEMA(24) increases the WCA of silica to 32°, indicating a large density of exposed PPO blocks upon adsorption. After adsorption of EO(132)PO(50)EO(132) and DMAEMA(24)-EO(132)PO(50)EO(132)-DMAEMA(24) on PP, the WCA is reduced by ≈14° and ≈28°, respectively, due to the exposed hydrophilic EO and highly water-soluble DMAEMA segments on the surfaces. The extent of surface coverage at saturation at the polypropylene/liquid interfaces (≈31 and 40 nm(2)/molecule obtained by QCM and SPR, respectively) is much lower, as expected, when compared with results obtained at the air/liquid interface, where a tighter packing is observed. The percentage of water coupled to the adsorbed cationic polymer decreases with solution ionic strength. Overall, these observations are ascribed to the effects of electrostatic screening, polymer hydrodynamic size, and solvency.     

基于聚琥珀酰亚胺衍生物仿生超亲水表面的制备及性能

利用对聚琥珀酰亚胺(PSI)的亲核加成反应,仿生设计合成侧基带有多巴胺和磺酸甜菜碱两性离子基团的新型聚琥珀酰亚胺衍生物(PSI-DA-ZW);通过聚琥珀酰亚胺衍生物中多巴邻苯二酚基团的氧化自聚和沉积,制备了仿生超亲水功能涂层表面(PSI-DA-ZW/glass).利用X射线光电子能谱仪(XPS)、扫描电子显微镜(SEM...     

Stimuli‐responsive antifouling polyisobutylene‐based biomaterials via modular surface functionalization

This article demonstrates a new, modular approach to surface functionalization that harnesses chain entanglement. A layer of functionalized polyisobutylene, (PIB)‐ω, where ω = ‐OH, ‐thymine (T), ‐hexaethylene glycol (HEG), poly(ethylene glycol) (‐PEG‐OH), methoxy‐functionalized poly(ethylene glycol) (‐PEG‐OCH₃), and ‐tetraethylene glycol‐α‐lipoate (TEG‐αL) was adhered to PIB‐based thermoplastic elastomer (TPE) surfaces. X‐ray photoelectron spectroscopy (XPS) at angles ranging from 20° to 75° showed decreasing polar group concentration with increasing penetration depth, confirming segregation of polar groups toward the surface. Water contact angle (WCA) of the PIB‐based TPE dropped from 95° to 79°?83° upon coating, and soaking in water for 24 h further decreased the WCA. Dynamic WCA measurements showed 40–30° receding angles, showing that stimulus from an aqueous environment elicits enrichment of polar groups on the surface. Fibrinogen (Fg) adsorption on the various surfaces was quantified using surface plasmon resonance (SPR). Static and dynamic WCA did not vary significantly among TPE + PIB‐ω surfaces, but there were dramatic differences in Fg adsorption: 256 ng/cm² was measured on the native TPE, which dropped to 40 and 22 ng/cm² on PIB‐PEG‐OCH₃ and PIB‐PEG‐OH‐coated surfaces. PIB‐TEG‐αL‐coated surfaces presented the lowest Fg adsorption with 14 ng/cm². © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 1742–1749     

Easy Synthesis of Ageing-Resistant Coatings with Tunable Wettability by Atmospheric Pressure Plasma

This study presents a simple and dry approach to synthesize stable, thin organic coatings with tunable wettability by injecting appropriate quantities of propargyl methacrylate (propaMA) and acrylic acid (AA) into a dielectric barrier discharge operating at atmospheric pressure. Deposition rates of up to 11 nm s^?1 can be achieved, thanks to the high reactivity of the propaMA monomer in the discharge. The AA monomer exhibits a weaker reactivity but, as evidenced by IRRAS and XPS analyses, allows introducing polar groups into the coating, thereby modifying the surface wettability. The surface is thus shown to be tunable from highly hydrophobic (WCA = 140°, pure propaMA coatings) to highly hydrophilic (WCA = 15°, pure AA coatings) by adjusting the monomer ratio in the discharge. These coatings have been deposited on polypropylene (PP) substrates, and the resulting WCA is shown to remain constant for at least 64 days, ageing that is remarkably slow compared with plasma functionalization that usually leads to rapid hydrophobic recovery.     

To adjust wetting properties of organic surface by in situ photoreaction of aromatic azide

This article describes development of a simple and convenient method to provide stable low-surface-energy coatings on organic surfaces, by designing and synthesizing a surface-reactive molecule 4-azido-N-dodecylbenzamide, which bears an azide group as the reactive surface anchor and an alkyl chain as the hydrophobic tail. After the hydrophobic modification, rough organic surfaces with contact angle of about 0 degrees can change their surface wetting properties from superhydrophilicity to superhydrophobicity, whose contact angles are above 152 degrees and tilt angles lower than 5 degrees. Moreover, by changing the alkyl chain to a PEO segment, a similar concept can be used to adjust the surface wetting properties from hydrophobic (contact angle approximately 130 degrees) to superhydrophilic (contact angle approximately 0 degrees).     

Origins of thermodynamically stable superhydrophobicity of boron nitride nanotubes coatings

Superhydrophobic surfaces are attractive as self-cleaning protective coatings in harsh environments with extreme temperatures and pH levels. Hexagonal phase boron nitride (h-BN) films are promising protective coatings due to their extraordinary chemical and thermal stability. However, their high surface energy makes them hydrophilic and thus not applicable as water repelling coatings. Our recent discovery on the superhydrophobicity of boron nitride nanotubes (BNNTs) is thus contradicting with the fact that BN materials would not be hydrophobic. To resolve this contradiction, we have investigated BNNT coatings by time-dependent contact angle measurement, thermogravimetry, IR spectroscopy, and electron microscopy. We found that the wettability of BNNTs is determined by the packing density, orientation, length of nanotubes, and the environmental condition. The origins of superhydrophobicity of these BNNT coatings are identified as (1) surface morphology and (2) hydrocarbon adsorbates on BNNTs. Hydrocarbon molecules adsorb spontaneously on the curved surfaces of nanotubes more intensively than on flat surfaces of BN films. This means the surface energy of BNNTs was enhanced by their large curvatures and thus increased the affinity of BNNTs to adsorb airborne molecules, which in turn would reduce the surface energy of BNNTs and make them hydrophobic. Our study revealed that both high-temperature and UV-ozone treatments can remove these adsorbates and lead to restitution of hydrophilic BN surface. However, nanotubes have a unique capability in building a hydrophobic layer of adsorbates after a few hours of exposure to ambient air.     

Synthesis of a thermosensitive surface by construction of a thin layer of poly (N-isopropylacrylamide) on maleimide-immobilized polypropylene

Thermosensitive surfaces were developed by the grafting of a thin layer of PNIPAAm through an UV-induced photopolymerization reaction of vinyl monomers with a free radical-activated polypropylene (PP) surface. PNIPAAm layer covering the PP surface corrected, to some extension, both depressions and fissures of the previously modified PP surfaces. The layered surfaces have morphological characteristic different from those of the non-layered surfaces, and their thickness was dependent on irradiation time. Water contact angles of the layered surfaces revealed a transition at approximately 33.5-36.5 °C as a result of a response to the variation of temperature. There was an increase in the values of the contact angles with an increase in temperature from 26 °C to 44 °C, revealing the nature both hydrophilic and hydrophobic of the surfaces due to a conformational rearrangement of PNIPAAm exposing its isopropyl groups to the liquid drop. This work offers a chemically stable thermosensitive surface (because it is covalently structured) with great potential for use as sensors and actuators.     

Immobilization of amphiphilic polycations by catechol functionality for antimicrobial coatings

A new strategy for preparing antimicrobial surfaces by a simple dip-coating procedure is reported. Amphiphilic polycations with different mole ratios of monomers containing dodecyl quaternary ammonium, methoxyethyl, and catechol groups were synthesized by free-radical polymerization. The polymer coatings were prepared by immersing glass slides into a polymer solution and subsequent drying and heating. The quaternary ammonium side chains endow the coatings with potent antibacterial activity, the methoxyethyl side chains enable tuning the hydrophobic/hydrophilic balance, and the catachol groups promote immobilization of the polymers into films. The polymer-coated surfaces displayed bactericidal activity against Escherichia coli and Staphylococcus aureus in a dynamic contact assay and prevented the accumulation of viable E. coli, S. aureus, and Acinetobacter baumannii for up to 96 h. Atomic force microscopy (AFM) images of coating surfaces indicated that the surfaces exhibit virtually the same smoothness for all polymers except the most hydrophobic. The hydrophobic polymer without methoxyethyl side chains showed clear structuring into polymer domains, causing high surface roughness. Sum-frequency generation (SFG) vibrational spectroscopy characterization of the surface structures demonstrated that the dodecyl chains are predominantly localized at the surface-air interface of the coatings. SFG also showed that the phenyl groups of the catechols are oriented on the substrate surface. These results support our hypothesis that the adhesive or cross-linking functionality of catechol groups discourages polymer leaching, allowing the tuning of the amphiphilic balance by incorporating hydrophilic components into the polymer chains to gain potent biocidal activity.     

以砂纸为模板制作聚合物超疏水表面

报道了一种聚合物材料超疏水表面的简便制备方法. 以不同型号的金相砂纸为模板, 通过浇注成型或热压成型技术, 在聚合物表面形成不同粗糙度的结构. 接触角实验结果证明, 聚合物表面与水的接触角随着所用砂纸模板粗糙度的增加而加大, 其中粒度号为W7和W5砂纸制作的表面与水的接触角可超过150°, 显示出超疏水性质. 多种聚合物使用砂纸为模均可制备不同粗糙度及超疏水的表面, 本征接触角对复制表面浸润性的影响从Wenzel态到Cassie态而变小. 扫描电镜结果表明, 不规则形状的砂纸磨料颗粒构成了超疏水所需要的微纳米结构的模板.