MONOMOLECULAR FILMS OF POLYDIMETHYLSILOXANES ON ORGANIC LIQUIDS.
NAVAL RESEARCH LAB WASHINGTON D C
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A homologous series of polydimethylsiloxanes was spread as insoluble monomolecular films on water and on a number of organic liquids of varying surface tension and surface composition. The organic liquids studied as substrates were tricresyl phosphate, propylene carbonate, diethylphthalate, bis2-ethylhexyladipate, and hexadecane. Monolayer stability and insolubility were found to vary with the molecular weight of the polydimethylsiloxane and the polarity of the substrate liquid. Stable, reversible monomolecular films were formed on all substrates by the higher-molecular-weight polymers mol wt 6000 however, film stability decreased with decreasing polymer molecular weight and decreasing substrate polarity. On tricresyl phosphate and propylene carbonate the high-molecular-weight polymers adsorbed in a fully extended configuration at large areas per molecule, analogous to their behavior on water. With compression they assumed a helical configuration with six monomer units per helix. On the less polar substrates the polydimethylsiloxanes apparently remained in the helical configuration regardless of the state of compression. Author
- Atomic and Molecular Physics and Spectroscopy