Date of Award

Summer 1988

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)



First Advisor

Collins, J. M.

Second Advisor

Feldott, J.

Third Advisor

Mendelson, K. S.


The nature of the forces between the bilayers of lipid-water systems has been a major field of study. In this work involving neutral phospholipid systems we attempted to analyze the interbilayer forces and separate them into their components. We conclude that both attractive and repulsive forces exist between lipid bilayers and their resultant gives the net interbilayer force in the lipid-water interfaces. The separation between the bilayers is a function of the applied pressure until a limiting value of bilayer separation is reached. This limiting value of bilayer separation was found to be a characteristic of the lipid system. The presence of an attractive van der Waals force between the bilayers was established. An iterative technique was used to split the measured pressures into their components namely, the hydration and the van der Waals pressures The van der Waals pressures were found to be an inverse cube function of bilayer separation. It is observed that if the hypothesized hydration pressures were assumed to have an exponential form then the inferred van der Waals pressures also exhibited an exponential form.



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