When convergent syntheses of graft block copolymers diverge: The treachery of chemical images

Michael J. Maher, Haley J. Schibur, Frank S. Bates

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

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 languageEnglish (US)
Pages (from-to)3097-3104
Number of pages8
JournalJournal of Polymer Science, Part A: Polymer Chemistry
Volume55
Issue number18
DOIs
StatePublished - Sep 15 2017

Keywords

  • RAFT
  • block copolymers
  • elastomers
  • graft polymers
  • thermoplastics

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