PMMA Brushes Prepared in an Ionic Liquid

In this report, we show the synthesis of polymethylmethacrylate (PMMA) brushes in the room temperature ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]). The brushes were prepared on functionalized silicon by atom transfer radical polymerization (ATRP). Kinetic study of the ATRP process identified linear and dense brush growth up to thicknesses of 8.3 nm. We used the negligible vapor pressure of the IL as an advantage to prepare polymer brush coatings not only on substrates immersed in the reaction solution, but also in the confined geometry of a "micro" droplet. The living character of the ATRP synthesis supported this method because sequential addition of MMA to the microdroplet increased the brush thickness.