College Park, Maryland      June 6 - 10 , 2004

MP22: Suppression of Dewetting in Polystyrene Thin Films by Polymer Nanoparticles

H. Feng, R. M. Briber (Department of Materials Science and Engineering, University of Maryland), V. Y. Lee, R. D. Miller, Ho-Ch Kim (IBM Almaden Research Center, 650 Harry Road, San Jose CA 95120-6099)

The influence of nanoparticles based on star polymers on the dewetting of spun-cast linear polystyrene (PS) films is investigated as a function of temperature. The star polymers have polystyrene-benzocyclobutene copolymer arms which can undergo intra-molecular crosslinking to form more compact nanoparticles. The addition of a small amount of nanoparticles (either the uncrosslinked star polymer or the intra-molecular crosslinked polymer) to the linear PS leads to inhibition of dewetting in thin (30 nm) films on silicon wafer substrates at 175C. The different dewetting behavior between films containing the uncrosslinked star polymers or the crosslinked nanoparticles suggests that the system has the potential for tunable dewetting behavior, depending on the specifics of the star molecules. Neutron reflection (NR) measurements indicate there is an enrichment of nanoparticles at the polymer-silicon interface in as-cast PS films, and this segregation may be related to the suppression of dewetting in PS films by nanoparticles. Small angle neutron scattering data shows bulk PS are miscible with 5 wt% of nanoparticles over the temperature range of 23C to 175C, implying that the segregation is not due to the immiscibility of PS and nanoparticles.

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