Light-regulated growth of polymer chains from the surface of RAFT agent primed mesoporous silica nanoparticles

Abstract

Reversible addition-fragmentation chain transfer (RAFT) polymerization is one of the extensively explored and studied controlled radical polymerization methods. Recently, in comparison to the conventional RAFT polymerization process, visible light-regulated photo-induced electron/energy transfer (PET)-RAFT polymerization has picked up interest. With an ever-increasing desire for greener and more sustainable methods for synthesis, techniques such as PET-RAFT polymerization can be well adapted as an alternative approach for performing a variety of syntheses. Keeping this in mind we step forward with the synthesis of mesoporous silica nanoparticles containing an in-built RAFT agent using a stepwise co-condensation method. Herein, we report a facile synthesis of an organic-inorganic hybrid system in which surface-initiated RAFT polymerization was performed using several monomers (hydrophobic and hydrophilic) from RAFT agent primed mesoporous silica nanoparticles (RAFT-MSNs). The surface-initiated RAFT polymerization was carried through thermally initiated polymerization using AIBN and visible light-regulated PET-RAFT polymerization using Eosin Y as a photocatalyst. The light-regulated PET-RAFT polymerization was carried out smoothly in a shorter time frame as compared to the thermally initiated RAFT polymerization. A variety of characterization methods were used to confirm the successful grafting of polymeric chains from the surface of RAFT-MSNs. Hence, by appropriate polymer functionalization of mesoporous silica nanoparticles with stimuli-responsive polymers or polymers bearing functional groups, these organic-inorganic hybrids can be studied in a wide variety of applications such as drug delivery, catalysis, nanoconfinement, etc.