Cascade synthesis of chiral block copolymers combining lipase catalyzed ring opening polymerization and atom transfer radical polymerization

J.W. Peeters, A.R.A. Palmans, M.A.J. Veld, F.J.E. Scheijen, A. Heise, E.W. Meijer

Research output: Contribution to journalArticleAcademicpeer-review

97 Citations (Scopus)

Abstract

The enantioselective polymerization of methyl-substituted -caprolactones using Novozym 435 as the catalyst was investigated. All substituted monomers could be polymerized except 6-methyl--caprolactone (6-MeCL), which failed to propagate after ring opening. Interestingly, an odd-even effect in the enantiopreference of differently substituted monomers was observed. The combination of 4-methyl--caprolactone with Novozym 435 showed good enantioselectivity also in bulk polymerization and resulted in enantiomerically enriched P((S)-4-MeCL) (eep up to 0.88). Subsequently, a novel initiator combining a primary alcohol to initiate the ring opening polymerization and a tertiary bromide to initiate atom transfer controlled radical polymerization (ATRP) was synthesized, and showed high initiator efficiencies (>90%) in the ring opening polymerization of 4-methyl--caprolactone in bulk. In addition, the enantioselectivity was retained (E = 11). By using Ni(PPh3)2Br2 as the ATRP catalyst, Novozym 435 could be effectively inhibited at the desired conversion of 4-methyl--caprolactone, thus ensuring a high enantiomeric excess in the polymer backbone. At the same time, Ni(PPh3)2Br2 catalyzed the ATRP of methyl methacrylate resulting in the formation of P((S)-4-MeCL-b-MMA) block copolymers. By this combination of two inherently different polymerization reactions, chiral P((S)-4-MeCL-b-MMA) block copolymers can be conveniently obtained in one pot without intermediate workup.
Original languageEnglish
Pages (from-to)1862-1868
JournalBiomacromolecules
Volume5
Issue number5
DOIs
Publication statusPublished - 2004

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