The Lateral Electric Conduction of Foam Lipid Films with the Transition of Film Thickness.

1991 Fiscal Year Final Research Report Summary

• Project/Area Number: 01540290
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: 物性一般（含極低温･固体物性に対する理論）
• Research Institution: Chiba University
• Principal Investigator: TOZAKI Ken-ichi Chiba University Department of Education Assistant Professor, 教育学部, 助教授 (30102031)
• Co-Investigator(Kenkyū-buntansha): YAMANAKA Teruko Chiba University Department of Education Professor, 教育学部, 教授 (90017905)
• Project Period (FY): 1989 – 1990
• Keywords: Electric Conductivity / Foam Film / Phospholipid / Calcium Ion / Salt Effect / Film Thickness / Black Film / Lysolecithin

Research Abstract

We measured lateral conductivity kappa_f (ohm-1)along the polar heads of black films formed from solutions of lysophosphatidylcholine in the presence of electrolyte. The measurements were performed in the range of electrolyte concentration from 10^<-4> to 10^<-1> M and temperature from 25 to 45ﾟC, using cylindrical films drawn between two coaxial, hollow, cylindrical Pt electrodes.
In the case of NaCl, kappa_f increases proportionally with bulk concentration of NaCl. On the other hand, at low CaCl_2 concentration, kappa_f is small up 'to about lmM, where kappa_f increases dramatically and then increases gradually with further increase in CaCl_2 concentration. It is observed that on increasing CaCl_2 concentration, at the same time the transitions of equilibrium thickness of films take place.
Further, activation energies E_f were obtained from Arrhenins PlOtS of kappa_f. In the case of CaCl_2, E_f's for both silver and common films are nearly equal to the activation energy E of bulk solution. For the Newton black films formed at low CaCl_2 concentration, E_f is about 2 - 3 times higher than E. On the other hand, for the Newton black films formed at high CaCl_2 concentration, E_f is close to tile activation energy for bulk solution.
We'll discuss the dependence kappa_f on the electrolyte concentration, by using the values of the film thickness, bulk conductivity and the activation energy of kappa_f.