Combining RAFT precipitation polymerization and surface-initiated RAFT polymerization: an efficient approach to prepare hairy particles—supported proline
In this paper, a simple and efficient approach for obtaining hairy particles supported proline system is described. The catalysts were synthesized by the modification of polymer microspheres via surface-initiated RAFT polymerization. Microspheres containing either carboxyl or ester groups were synthesized by RAFT precipitation copolymerization, and the functional groups influenced the yield and asymmetric selectivity of chiral product in different DMF–H2O solvents during a representative aldol reaction. Compared with hairy particles 2 with ester groups, hairy particles 1 with carboxyl groups exhibited better catalytic activity and asymmetric selectivity, providing more suitable microenvironments for the aldol reaction. Importantly, the hairy particles 1, as catalyst, can be easily recovered and recycled, and show no significant loss of activity and selectivity after 6 cycles. The application of RAFT precipitation polymerization together with the facile surface-grafting approach provides a general and promising way for chiral catalyst load.