Open AccessWhen convergent syntheses of graft block copolymers diverge: The treachery of chemical images
Author(s) -
Maher Michael J.,
Schibur Haley J.,
Bates Frank S.
Publication year - 2017
Publication title -
journal of polymer science part a: polymer chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.768
H-Index - 152
eISSN - 1099-0518
pISSN - 0887-624X
DOI - 10.1002/pola.28660
Subject(s) - copolymer , raft , polymer chemistry , grafting , maleimide , chain transfer , polymerization , styrene , chemistry , reversible addition−fragmentation chain transfer polymerization , materials science , radical polymerization , polymer , organic chemistry
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). © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3097–3104