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Scanning Probe Microscope Study of Mixed Chain-Length Phase-Segregated Langmuir-Blodgett Monolayers

Published online by Cambridge University Press:  10 February 2011

D.D. Koleske
Affiliation:
Chemistry Division, Code 6177, Naval Research Laboratory, Washington, DC 20375–5342
W.R. Barger
Affiliation:
Chemistry Division, Code 6177, Naval Research Laboratory, Washington, DC 20375–5342
G.U. Lee
Affiliation:
Chemistry Division, Code 6177, Naval Research Laboratory, Washington, DC 20375–5342
R.J. Colton
Affiliation:
Chemistry Division, Code 6177, Naval Research Laboratory, Washington, DC 20375–5342
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Abstract

Using a scanning probe microscope, the influence of adhesion on measured film height of mixed-chain-length fatty acid Langmuir-Blodgett monolayers was investigated. A 1:1 mixture of CH3[CH2]22COOH and CH3[CH2]14COOH, was deposited in which the long chain-length acid, C24, was segregated from the short chain-length acid, C16. Two experiments were performed, contact scanning and force curve mapping. From both experiments, the film height difference measured between the C16 and C24 regions was larger than expected. Adhesion of the tip was 20% larger over the C16 acid regions. Using a compressional modulus derived from film pressure vs. area isotherms of the pure components, the adhesion difference and apparent filmheight difference over the two regions can be understood.

Type
Research Article
Copyright
Copyright © Materials Research Society 1997

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References

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