高等学校化学学报 ›› 1995, Vol. 16 ›› Issue (S1): 138.

• 研究论文 • 上一篇    下一篇

Contact-Angle Titrations of Cysteamine Selfassembled Monolayers on Gold--A Sensitive Tool for Monitoring the Surface Modification Process

YU Hua-zhong, ZHAO Jian-wei, WANG Yong-qiang, CHENG Ji-zhi, CAI Sheng-min, LIU Zhong-fan   

  1. Electrophotonic Intelligent Materials Laboratory, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
  • 收稿日期:1995-08-05 出版日期:1995-12-31 发布日期:1995-12-31
  • 基金资助:

    State Science Technology Committee the State Education Committee and the National Natural Science Foundation of China

Contact-Angle Titrations of Cysteamine Selfassembled Monolayers on Gold--A Sensitive Tool for Monitoring the Surface Modification Process

YU Hua-zhong, ZHAO Jian-wei, WANG Yong-qiang, CHENG Ji-zhi, CAI Sheng-min, LIU Zhong-fan   

  1. Electrophotonic Intelligent Materials Laboratory, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
  • Received:1995-08-05 Online:1995-12-31 Published:1995-12-31
  • Supported by:

    State Science Technology Committee the State Education Committee and the National Natural Science Foundation of China

摘要:

The self-assembled monolayers (SAMs). which were prepared by spontaneous adsorption of cysteamine on gold surface, were characterized using contact-angle titrations. Contact-angle titration data acquired for the cysteamine SAMs exhibited a smooth transition in contact angle between plateau regions at low and high pH value. The surface pKb, was estimated to be 1.8±0.2, much lower than that in solution. The electroactive azobenzene group was anchored to the monolayer via amide surface reaction. Thus the formed SAMs were further subjected to exchange in dilute pentanethiol soluition. At each stage of modification, the surface was monitored by con-tact-angle titration and cyclic voltanimetry. It was found that the titration curves obviously shifted to the higher contact-angle direction with the increase of surface hydrophobicity. The results are in good agreement with the cyclic voltammetric measurements, demonstrating that the contact-angle titration is a useful technique for monitoring the step by step surface reactions.

关键词: Cysteamine self-assembled monolayers (SAMs), Contact-angle titration, Step-by-step surface reaction

Abstract:

The self-assembled monolayers (SAMs). which were prepared by spontaneous adsorption of cysteamine on gold surface, were characterized using contact-angle titrations. Contact-angle titration data acquired for the cysteamine SAMs exhibited a smooth transition in contact angle between plateau regions at low and high pH value. The surface pKb, was estimated to be 1.8±0.2, much lower than that in solution. The electroactive azobenzene group was anchored to the monolayer via amide surface reaction. Thus the formed SAMs were further subjected to exchange in dilute pentanethiol soluition. At each stage of modification, the surface was monitored by con-tact-angle titration and cyclic voltanimetry. It was found that the titration curves obviously shifted to the higher contact-angle direction with the increase of surface hydrophobicity. The results are in good agreement with the cyclic voltammetric measurements, demonstrating that the contact-angle titration is a useful technique for monitoring the step by step surface reactions.

Key words: Cysteamine self-assembled monolayers (SAMs), Contact-angle titration, Step-by-step surface reaction

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