Acta Phys. -Chim. Sin. ›› 2015, Vol. 31 ›› Issue (10): 1924-1931.doi: 10.3866/PKU.WHXB201509061

• SOFT MATTER • Previous Articles     Next Articles

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)


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


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