Polymer grafting on nitrone functionalized green silica via “grafting from” and “grafting to” approaches through enhanced spin capturing polymerization and a 1,3-dipolar cycloaddition reaction

Abstract

The nitrone functionality is proven to have the potential to enable polymer conjugation via enhanced spin-capturing polymerization (ESCP) and nitrone-mediated radical coupling (NMRC); however, reactions using nitrone have been less explored for surface functionalization of solid substrates. In addition, nitrone has a unique ability to undergo a 1,3-dipolar cycloaddition reaction which has not been explored for polymer conjugation and polymer “grafting from” solid substrates. In this work, nitrone-functionalized silica derived from rice husk ash has been used for polymer grafting via “grafting from” and “grafting to” through spin capturing and 1,3-dipolar cycloaddition reactions. The ability of the nitrone functionality to undergo 1,3-dipolar cycloaddition was monitored using styrene and nitrone, nitrone-functionalized silica and isobornyl acrylate, as well as nitrone-functionalized polystyrene and a polystyrene macromonomer. The nitrone functionality was introduced onto the mercaptopropyl functionalized silica surfaces synthesized via a co-condensation reaction. The extent of polymer grafting via ESCP has been analyzed at three different conversions. The effect of the surface area of silica and the method of functionalization on polymer grafting density has been studied. The efficiency of polymer grafting over the nitrone functionality on the surface indicates the potential of surface nitrone functionalities to undergo polymer grafting via “grafting from” and “grafting to” approaches.