Size effect of semiconductor quantum dots as photocatalysts for PET-RAFT polymerization†
The use of semiconductor quantum dots (QDs) as photocatalysts for photo-induced electron or energy transfer (PET) reversible addition–fragmentation chain transfer (RAFT) polymerization is increasingly attractive owing to their stable photo activity and efficient charge transfer. However, previous studies in the field have not discussed the effect of the quantum size of the QDs particles, which is known to have a significant effect on the light absorption and charge transfer. Therefore, the aim of this work is to investigate PET-RAFT polymerization with different sizes of CdSe QDs. With an increase in the particle size of the QDs, the polymerization rate remarkably increased (higher apparent propagation rate constant, kappp) and the experimental molecular mass demonstrated a better fit with the theoretical values (I* = Mn,th/Mn,GPC, close to 1), indicating a more ideal control radical polymerization system with the larger QDs. Furthermore, the better controllability with larger CdSe QDs was extended to a PET-RAFT system with different irradiation lights, solvents and monomers. This work is considered to be a valuable contribution to semiconductor QD catalyst PET-RAFT polymerization.