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J Colloid Interface Sci. 2002 Oct 15;254(2):306-15.

Surface modification of Sylgard-184 poly(dimethyl siloxane) networks by ultraviolet and ultraviolet/ozone treatment.

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  • 1Department of Chemical Engineering, North Carolina State University, Raleigh, North Carolina, 27695-7905, USA.

Abstract

We report on the surface modification of Sylgard-184 poly(dimethyl siloxane) (PDMS) networks by ultraviolet (UV) radiation and ultraviolet/ozone (UVO) treatment. The effects of the UV light wavelength and ambient conditions on the surface properties of Sylgard-184 are probed using a battery of experimental probes, including static contact angle measurements, Fourier transform infrared spectroscopy, near-edge X-ray absorption fine structure, and X-ray reflectivity. Our results reveal that when exposed to UV, the PDMS macromolecules in the surface region of Sylgard-184 undergo chain scission, involving both the main chain backbone and the side groups. The radicals formed during this process recombine and form a network whose wetting properties are similar to those of a UV-modified model PDMS. In contrast to the UV radiation, the UVO treatment causes very significant changes in the surface and near-surface structure of Sylgard-184. Specifically, the molecular oxygen and ozone created during the UVO process interact with the UV-modified specimen. As a result of these interactions, the surface of the sample contains a large number of hydrophilic (mainly -OH) groups. In addition, the material density within the first approximately 5 nm reaches about 50% of that of pure silica. A major conclusion that can be drawn from the results and analysis described in this work is that the presence of the silica fillers in Sylgard-184 does not alter the surface properties of the UVO- and UV-modified Sylgard-184.

PMID:
12702402
[PubMed]
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