| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 1998: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1997: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
In this study, we investigated the mesoscopic surface structure of polymer gels (such as surface roughness and characteristic length) using an atomic force microscopy (AFM), as well as its role in determining the macroscopic functions (such as adhesion, surface tension, and friction).
1. Surface structure of poly(N-isopropylacrylamide) (NIPA) gels in water was studied using AFM, and it was established that the surface conformation is characterized by the sponge-like domains with submicrometer scale. We investigated the effect of the inhomogeneities of the bulk networks on the domain structure, as well as the effect of the temperature change. Surface roughness due to the sponge-like domains was discussed in terms of the auto-correlation function and of the power spectral density calculated from the topographies.
2. In order to discuss the relation between the surface roughness and the macroscopic surface properties, the static contact angle of sessile air bubbles in water was measured for NIPA gels as a model gel with hydrophobic interactions. The static contact angle versus temperature was found to depend on the inhomogeneities of the bulk networks. We showed that the static contact angle can be governed not only by the chemical (in the present case, the balance of the hydrophobic-hydrophilic interactions) but also by the physical properties of hydrophobic polymer gels in response to a temperature change. Of the various effective physical factors being considered, the following would be essential in determining the static contact angle : the polymer density, the surface roughness, and the network homogeneity.
We believe that the present study is of crucial importance for the future development and application of new technologies based on the basic concepts gained from the fundamental studies of polymer gel surfaces.
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