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Publication Citation: Control of Moisture at Buried Polymer / Alumina Interfaces Through Subtrate Surface Modification

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Author(s): B D. Vogt; Vivek M. Prabhu; Christopher L. Soles; Sushil K. Satija; Eric K. Lin; Wen-Li Wu;
Title: Control of Moisture at Buried Polymer / Alumina Interfaces Through Subtrate Surface Modification
Published: March 15, 2005
Abstract: Moisture absorption in poly(4-tert-butoxycarbonyl-oxystyrene) (PBOCSt) films supported on Al2O3 sputter coated silicon wafers is measured using neutron and x-ray reflectivity. Accumulation of water at the interface during moisture exposure results in film thickness dependent swelling for ultrathin PBOCSt films. The swelling of a film on Al2O3 is less than the swelling of a film of the same thickness on SiOx for films thinner than 20 nm. This is due to comparatively less moisture accumulation at the Al2O3 / PBOCSt interface. A simple, zero adjustable parameter model consisting of a fixed water rich layer at the interface and bulk swelling through the remainder of the film describes the thickness dependent swelling. The influence of four different Al2O3 surface treatments on the moisture distribution within PBOCSt films was examined: bare Al2O3, t-butylphosphonic acid, phenylphosphonic acid, and n-octyltrichlorosilane. Both the phenyl and the octyl surface treatments reduce the accumulation of water at the polymer / substrate interface. The t-butyl treatment does not reduce the interfacial water concentration, presumably due to insufficient surface coverage
Citation: Langmuir
Volume: 21
Issue: 6
Pages: pp. 2460 - 2464
Keywords: interfaces;moisture barrier;reflectivity;thin films
Research Areas: Polymers
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