物理化学学报 >> 2015, Vol. 31 >> Issue (10): 1924-1931.doi: 10.3866/PKU.WHXB201509061

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苄基取代甜菜碱对聚四氟乙烯表面润湿性的影响

胡嵩霜1,2,张磊1,徐志成1,宫清涛1,靳志强1,张路1(),赵濉1()   

  1. 1 中国科学院理化技术研究所,北京100190
    2 中国科学院大学,北京100190
  • 收稿日期:2015-06-26 发布日期:2015-10-10
  • 基金资助:
    国家科技重大专项(2011ZX05011-004);国家自然科学基金(51373192)

Effect of Benzyl-Substituted Alkyl Betaine on the Wettability of a Poly(tetrafluoroethylene) Surface

Song-Shuang. HU1,2,Lei. ZHANG1,Zhi-Cheng. XU1,Qing-Tao. GONG1,Zhi-Qiang. JIN1,Lu. ZHANG1(),Sui. ZHAO1()   

  1. 1 Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
    2 University of Chinese Academy of Sciences, Beijing 100190, P. R. China
  • Received:2015-06-26 Published:2015-10-10
  • Supported by:
    the National Science & Technology Major Project, China(2011ZX05011-004);National Natural ScienceFoundation of China(51373192)

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摘要：

利用座滴法研究了两性离子表面活性剂苄基取代烷基羧基甜菜碱(BCB)和苄基取代烷基磺基甜菜碱(BSB)在聚四氟乙烯(PTFE)表面上的润湿性质,考察了表面活性剂浓度对接触角的影响趋势,并讨论了粘附张力、固-液界面张力和粘附功的变化规律.研究发现,在低浓度时,表面活性剂通过疏水作用吸附到PTFE表面,疏水链苄基取代支链化使其在固-液界面上的吸附明显低于气-液界面,接触角在很大的范围内保持不变.当体相浓度增加到大于临界胶束浓度(cmc)时, BCB和BSB分子在固-液界面上继续吸附,分子逐渐直立,造成PTFE-液体之间的界面张力(γSL)进一步降低,表面亲水性增加,接触角随浓度增加明显降低;另一方面, BSB由于具有较大的极性头,在高浓度时空间阻碍作用明显,导致其对PTFE表面润湿性改变程度小于BCB.

关键词: 两性离子表面活性剂, 空间位阻, 接触角, 聚四氟乙烯表面

Abstract:

The wetting properties of aqueous solutions of zwitterionic surfactants, benzyl-substituted alkyl carboxylbetaine (BCB), and benzyl-substituted alkyl sulfobetaine (BSB) on a poly(tetrafluoroethylene) (PTFE) surface were investigated using sessile drop analysis. The influences of surfactant concentration on surface tension, contact angle, adhesional tension, PTFE-solution interfacial tension (γSL) and adhesion work were examined. The results indicate that at low bulk concentration, surfactant molecules adsorb onto PTFE through hydrophobic interactions. Moreover, the adsorption of branched surfactants on the air-solution interface is higher than that on the PTFE-liquid interface and the values of contact angle for BCB and BSB remain almost constant over a wide range of surfactant concentrations. The adsorption of BCB and BSB molecules on PTFE are greatly enhanced again when the bulk concentration exceeds the critical micelle concentration. The molecules straighten, with hydrophilic group oriented towards the bulk phase, resulting in a decrease in γSL and a decrease in contact angle. The introduction of larger polar group in BSB makes it difficult to change the contact angle to the same extent as BCB at high surfactant concentrations because of steric effects.

Key words: Zwitterionic surfactant, Steric effect, Contact angle, Poly(tetrafluoroethylene) surface