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The Wilhelmy plate technique was used to measure the dynamic surface tension of poly(N-isopropylacrylamide)(poly(NIPAM)) at the air−water interface as a function of poly(NIPAM) concentration and temperature. Initial periods of a negligible decrease of the dynamic surface tension were observed at the lowest concentration of poly(NIPAM). The decay rate of the surface tension was well interpreted by taking account of the solution properties of poly(NIPAM) under the assumption of diffusion-controlled adsorption kinetics. The experimental data were numerically fitted with an empirical Hua−Rosen equation, and they were in good agreement with each other. Furthermore, the ellipsometric results were compared with those for the poly(NIPAM) monolayer spread at the air−water interface from its aqueous solution.

Polymer monolayers of PEO, PTHF, PVAc, PMMA, and PMLG spread at the air-water interface have been investigated by ellipsometry and surface pressure measurements. From their surface pressure ( ) vs surface area (A) curves, PEO, PTHF, and PVAc were classified as expanded monolayers, while the other polymers belonged to the condensed monolayers. Ellipsometry gave two parameters of (the phase difference between the light components perpendicular and parallel to the plane of incidence) and (tan is the ratio of the reflection coefficients of the perpendicular and parallel components). The values showed a very sensitive change as a function of surface concentration of polymer monolayer spread at the air-water interface. Change in , 5 , increased linearly with for PTHF and PVAc monolayers, while 5 values of PEO, PMMA, and PMLG monolayers deviated from a linear relation above a given at which reaches a plateau value. Below such surface concentrations thicknesses calculated from ellipsometry were less than 5 nm, independent of polymer species. With further increase in the thicknesses of PTHF and PVAc monolayers increased to more than 10 nm.

PolyUV-isopropylacrylamide) (poly(NIPAM)) film spread at the air-water interface from its aqueous solution has been investigated by surface pressure and ellipsometric measurements at two temperatures (16.0 and 31.3 °C). The surface pressure steeply increased at low real spread concentration of poly(NIPAM), and it more gradually attained a plateau one at high temperature. The plateau surface pressure at 16.0 °C was lower than that at 31.3 °C. The amount of polymer adsorbed at the air-water interface was determined by ellipsometry, and its plateau adsorbed amount at 31.3 °C was twice as large as that at 16.0 °C, whereas the thickness of the adsorbed layer at 16.0 °C was larger than that at 31.3 °C. Such an adsorption behavior at the air-water interface was strongly related to the transition of poly(NIPAM) from a hydrophilic to a hydrophobic structure in bulk solution. Moreover, it was found that some portions of the spread polymer were desorbed from the interface and the magnitude of the adsorbed amount was similar to that on the silica surfaces.