Structural aging and stiction dynamics in confined liquid films

Shinji Yamada

研究成果: Article

11 引用 (Scopus)

抜粋

The static friction (stiction) of the molecularly thin films of an irregularly shaped molecule 1,3-dimethylbutyl octyl ether (DBOE) confined between mica surfaces was investigated using the surface forces apparatus. Stop-start experiments were carried out and the stiction spike was measured as a function of surface stopping (aging) time t and applied pressure P. The results show two relaxation processes, one on stopping and one on starting, where each process has a fast and a slow time constant. For stopping mode, there is no stiction spike when t is shorter than a characteristic nucleation time, τn (fast time constant). When t exceeds τn, stiction spike appears whose height increases logarithmically with t. With regard to starting, the relaxation behavior was evaluated by a double exponential fit of the slipping regime (force decay) of the spike and two time constants (τ1 and τ2) were obtained. The fast time constant on starting τ1 is almost equal to that on stopping τn. To the best of our knowledge, this is the first direct observation of the agreement of the time constant on stopping and that on starting, indicative of a reversible structural transition (solid-liquid transition) in the stop-start stiction dynamics. The two fast time constants exhibit exponential dependence on P, which implies a glasslike nature of the transition. Comparison with the stick-slip friction reveals that the solid-liquid transition involved in stiction and that in stick-slip dynamics is different for DBOE; first-order-like discontinuous transition is suggested for stick-slip friction. Origins of the different solid-liquid transition dynamics in stiction and in stick-slip friction are discussed by comparing with the dynamics of other confined liquid systems.

元の言語English
記事番号184708
ジャーナルJournal of Chemical Physics
131
発行部数18
DOI
出版物ステータスPublished - 2009 12 1

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

フィンガープリント Structural aging and stiction dynamics in confined liquid films' の研究トピックを掘り下げます。これらはともに一意のフィンガープリントを構成します。

  • これを引用