Authors: K. Viswanathan, T.E. Long and T.C. Ward
Affilation: Virginia Tech, United States
Pages: 335 - 338
Keywords: star polymers, surface modification, polymer mushrooms and brushes
The synthesis of trimethoxysilane end-capped linear polystyrene (PS), star-branched PS, and subsequent silicon (Si) surface modification with the linear and star polymers are described. Trimethoxysilane terminated PS was synthesized using sec-butyl lithium initiated anionic polymerization of styrene and subsequent end-capping of the living anions with p-chloromethylphenyl trimethoxysilane (CMPTMS). Acid catalyzed hydrolysis and condensation of the trimethoxysilane end-groups resulted in star-branched PS, and NMR spectroscopy and SEC analysis were used to characterize the star polymers. This is the first report of core-functionalized star-shaped polymers as surface modifiers and the first comparative study showing differences in surface topography between star and linear polymer modified surfaces. Surface-sensitive techniques such as ellipsomtery, contact angle goniometry, and AFM were used to confirm the attachment of star PS as well as to compare the characteristics of the star and linear PS modified Si wafers. The polymer film properties were referenced to polymer dimensions in dilute solution, which revealed that linear PS chains were in the intermediate brush regime and the star-branched PS produced a surface with covalently attached chains in the mushroom regime.