A thermodynamic method is employed to analyse the slip length of hydrophobic nanopatterned surface. The maximal slip lengths with respect to the hydrophobicity of the nanopatterned surface are computed. It is found th...A thermodynamic method is employed to analyse the slip length of hydrophobic nanopatterned surface. The maximal slip lengths with respect to the hydrophobicity of the nanopatterned surface are computed. It is found that the slip length reaches more than 50 μm if the nanopatterned surfaces have a contact angle larger than 160°. Such results are expected to find extensive applications in micro-channels and helpful to understand recent experimental observations of the slippage of nanopatterned surfaces.展开更多
Plasma immersion ion implantation(PIII) was used to fabricate micro/nano structures on monocrystalline Si surfaces with different ratios of mixed gases(SF_6/O_2). The micro/nano structures on the surfaces of the sampl...Plasma immersion ion implantation(PIII) was used to fabricate micro/nano structures on monocrystalline Si surfaces with different ratios of mixed gases(SF_6/O_2). The micro/nano structures on the surfaces of the sample were characterized by scanning electron microscopy(SEM) and atomic force microscopy(AFM). The results showed that with increasing ratio of mixed gases(SF_6/O_2), the height of the micro/nano structures first increased and then decreased. Contact-angle measurements indicated that the surfaces' micro/nano structures have an obvious effect on the contact-angle, and could cause a change in surface wettability. The theoretical analysis of contact-angle showed that the Wenzel and Cassie theories cannot predict the contact-angle of a roughened surface accurately, and should be corrected for practical applications using an actual model. Moreover, the contact-angle first increased and then decreased with increasing ratio of mixed gases(SF_6/O_2), which is in accordance with the change of the height of micro/nano structures.展开更多
Ultra-thin film of perfluorodecanoic acid expected to be excellent lubricant for micro-machines was prepared successfully on single crystal silicon substrate.The film was characterized by means of X-ray photoelectron ...Ultra-thin film of perfluorodecanoic acid expected to be excellent lubricant for micro-machines was prepared successfully on single crystal silicon substrate.The film was characterized by means of X-ray photoelectron spectroscopy (XPS) and contact-angle meter.The chemical reaction involved in the preparation of the ultra-thin film was discussed as well.After being immersed in a dilute aqueous solution of polyethyleneimine (PEI) for 15 minutes and rinsed with distilled water,the silicon substrate was coated with a thin film of PEI,which was then put into a dilute solution (1× 10－ 3 mol· L－ 1) of perfluorodecanoic acid in hexadecane.Subsequently the steady perfluorodecanoic acid ultra-thin film was developed on PEI coating in the presence of a covalent amide bond between carboxylic group and the primary or secondary amine groups of PEI.This process was accompanied by the contact angle changes of water droplet on the Si surface (see Table 1).Moreover,the reaction between perfluorodecanoic acid and PEI was significantly influenced by N,N′-dicyclohexylcarbodiimide (DCCD).The contact angle on the ultra-thin film of perfluorodecanoic acid is only 66.3° in the absence of DCCD in the reacting solution; it rises to 89.4° in the presence of DCCD.This indicates that the reaction between perfluorodecanoic acid and PEI was accelerated by DCCD,and the quality of perfluorodecanoic acid ultra-thin film thus improved.XPS analysis of the ultra-thin film indicates that the derivatization of PEI with perfluorodecanoic acid was accompanied by several changes.First,a large and highly symmetrical F 1s peak appeared at 688.3 eV (C－ F* ).Secondly,a new peak of N 1s appeared at 400.7 eV (chemical shift 1.4 eV),which was attributed to the N atom attached to the carbonyl group (O=C－ N* ).Thirdly,three new peaks of C 1s appeared at 286.1 eV (chemical shift 1.5 eV),288.1 eV (chemical shift 3.5 eV),and 291.0 eV (chemical shift 5.4 eV),respectively.These C 1s peaks were attributed to the C atom attached to the O=C－ N group (O=C�展开更多
为了解非离子型气湿反转剂在改变砂岩表面润湿性方面的作用效果,获得气润湿性良好的砂岩地层,提高凝析气藏的生产能力,分别采用接触角法和Owens二液法考察了非离子型表面活性剂处理前后砂岩岩心的气润湿程度和表面自由能,研究了无机盐...为了解非离子型气湿反转剂在改变砂岩表面润湿性方面的作用效果,获得气润湿性良好的砂岩地层,提高凝析气藏的生产能力,分别采用接触角法和Owens二液法考察了非离子型表面活性剂处理前后砂岩岩心的气润湿程度和表面自由能,研究了无机盐、温度和pH值对气润湿性的影响及气润湿反转的有效期。结果表明,质量分数为0.3%的非离子型氟碳表面活性剂(FG24)可将岩心表面的润湿性由液润湿性反转为强气润湿性,水相和油相在岩心表面的接触角由处理前的36.0°和0°分别增至141.3°和108.0°,且岩心的表面自由能由71.0 m N/m急剧降至3.29 m N/m。在pH值为1数10、无机盐溶液质量浓度为100 g/L、温度140℃范围内,油水相在岩心表面的接触角均大于90°;岩心可在60 d内保持强气润湿性。FG24可将岩心表面反转为強气湿性,并具有良好的耐盐性和耐温性。展开更多
基金Supported by the 100 Persons Project of the Chinese Academy of Sciences, the National Natural Science Foundation of China under Grant Nos 10474109 and 10674146, the National Basic Research Programme of China under Grant Nos 2006CB933000 and 2006CB708612. To whom correspondence should be addressed.
文摘A thermodynamic method is employed to analyse the slip length of hydrophobic nanopatterned surface. The maximal slip lengths with respect to the hydrophobicity of the nanopatterned surface are computed. It is found that the slip length reaches more than 50 μm if the nanopatterned surfaces have a contact angle larger than 160°. Such results are expected to find extensive applications in micro-channels and helpful to understand recent experimental observations of the slippage of nanopatterned surfaces.
基金financially supported by NSFC Project(Grant No.51376022)
文摘Plasma immersion ion implantation(PIII) was used to fabricate micro/nano structures on monocrystalline Si surfaces with different ratios of mixed gases(SF_6/O_2). The micro/nano structures on the surfaces of the sample were characterized by scanning electron microscopy(SEM) and atomic force microscopy(AFM). The results showed that with increasing ratio of mixed gases(SF_6/O_2), the height of the micro/nano structures first increased and then decreased. Contact-angle measurements indicated that the surfaces' micro/nano structures have an obvious effect on the contact-angle, and could cause a change in surface wettability. The theoretical analysis of contact-angle showed that the Wenzel and Cassie theories cannot predict the contact-angle of a roughened surface accurately, and should be corrected for practical applications using an actual model. Moreover, the contact-angle first increased and then decreased with increasing ratio of mixed gases(SF_6/O_2), which is in accordance with the change of the height of micro/nano structures.
文摘Ultra-thin film of perfluorodecanoic acid expected to be excellent lubricant for micro-machines was prepared successfully on single crystal silicon substrate.The film was characterized by means of X-ray photoelectron spectroscopy (XPS) and contact-angle meter.The chemical reaction involved in the preparation of the ultra-thin film was discussed as well.After being immersed in a dilute aqueous solution of polyethyleneimine (PEI) for 15 minutes and rinsed with distilled water,the silicon substrate was coated with a thin film of PEI,which was then put into a dilute solution (1× 10－ 3 mol· L－ 1) of perfluorodecanoic acid in hexadecane.Subsequently the steady perfluorodecanoic acid ultra-thin film was developed on PEI coating in the presence of a covalent amide bond between carboxylic group and the primary or secondary amine groups of PEI.This process was accompanied by the contact angle changes of water droplet on the Si surface (see Table 1).Moreover,the reaction between perfluorodecanoic acid and PEI was significantly influenced by N,N′-dicyclohexylcarbodiimide (DCCD).The contact angle on the ultra-thin film of perfluorodecanoic acid is only 66.3° in the absence of DCCD in the reacting solution; it rises to 89.4° in the presence of DCCD.This indicates that the reaction between perfluorodecanoic acid and PEI was accelerated by DCCD,and the quality of perfluorodecanoic acid ultra-thin film thus improved.XPS analysis of the ultra-thin film indicates that the derivatization of PEI with perfluorodecanoic acid was accompanied by several changes.First,a large and highly symmetrical F 1s peak appeared at 688.3 eV (C－ F* ).Secondly,a new peak of N 1s appeared at 400.7 eV (chemical shift 1.4 eV),which was attributed to the N atom attached to the carbonyl group (O=C－ N* ).Thirdly,three new peaks of C 1s appeared at 286.1 eV (chemical shift 1.5 eV),288.1 eV (chemical shift 3.5 eV),and 291.0 eV (chemical shift 5.4 eV),respectively.These C 1s peaks were attributed to the C atom attached to the O=C－ N group (O=C�
文摘为了解非离子型气湿反转剂在改变砂岩表面润湿性方面的作用效果,获得气润湿性良好的砂岩地层,提高凝析气藏的生产能力,分别采用接触角法和Owens二液法考察了非离子型表面活性剂处理前后砂岩岩心的气润湿程度和表面自由能,研究了无机盐、温度和pH值对气润湿性的影响及气润湿反转的有效期。结果表明,质量分数为0.3%的非离子型氟碳表面活性剂(FG24)可将岩心表面的润湿性由液润湿性反转为强气润湿性,水相和油相在岩心表面的接触角由处理前的36.0°和0°分别增至141.3°和108.0°,且岩心的表面自由能由71.0 m N/m急剧降至3.29 m N/m。在pH值为1数10、无机盐溶液质量浓度为100 g/L、温度140℃范围内,油水相在岩心表面的接触角均大于90°;岩心可在60 d内保持强气润湿性。FG24可将岩心表面反转为強气湿性,并具有良好的耐盐性和耐温性。
