A synthetic strategy to produce graft block copolymers (BCPs) with controlled grafting densities using both grafting-through and grafting-from methods is reported. For grafting-through, poly(4-methylcaprolactone-block-d,l-lactide) macromonomers were synthesized with a polymerizable maleimide end group. These macromonomers were copolymerized using reversible addition-fragmentation chain-transfer (RAFT) polymerization with styrene and various amounts of N-ethylmaleimide to control grafting density. A kinetic study showed that the macromonomers (>10 kDa) polymerized at the same rate as N-ethylmaleimide under RAFT conditions, suggesting that uniform grafting density could be achieved. However, incorporating more than 5–10 grafts per chain was found to be challenging and potentially limited by kinetics. A higher number of grafts per chain with controlled densities was achieved using a grafting-from technique. Macroinitiators of styrene, N-ethylmaleimide, and N-(2-hydroxyethyl)maleimide were copolymerized with a fixed density of grafting sites. Subsequently, BCPs were grown off of the macroinitiator using ring-opening transesterification polymerization (ROTEP).
|Original language||English (US)|
|Number of pages||8|
|Journal||Journal of Polymer Science, Part A: Polymer Chemistry|
|State||Published - Sep 15 2017|
- block copolymers
- graft polymers