ISSN:
0449-2951
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Monolayers of poly-2-vinylpyridine (2-PVP), of poly(methacrylic acid) (PMA), as well as of a polyampholyte containing definite proportions of 2-vinylpyridine and acrylic acid were investigated at the air-water interface. We studied particularly the ionization of the film. The variation of surface pressure with respect to the nature of the ionic subsolution was analyzed. At constant degree of ionization, two factors determine the surface pressure: the valence and the dimension of the counterion. The polyampholyte may be considered alternatively as a polycation or a polyanion depending on the pH value of the support. The small concentration of dipolar ions permits the presence in the same macromolecule of the properties of the poly-2-vinylpyridine and of the poly(methacrylic acid). Qualitatively, the influence of the counterions is reproduced for the three polyelectrolytes. With monovalent ions, a quantitative approach is possible. The surface pressure is analyzed in terms of current theories of the ionic double layer. The application of the Gouy-Chapman model gives satisfactory results at different polymer and ionic concentrations. The theory has been extended with success to completely and incompletely ionized monolayers. However, there is evidence that the Gouy-Chapman theory is obeyed only at high areas. For denser films, the discrepancy between the calculated and experimental pressure is often quite large. The inclusion of a “fluctuation potential” contribution to the surface pressure permits a good agreement between the theory and the experiments.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1965.100031204
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