Synthesis of Macrocyclic Poly(ε‐caprolactone) by Intramolecular Cross‐Linking of Unsaturated End Groups of Chains Precyclic by the Initiation

Abstract

Bioabbaubare cyclische Polyester werden hergestellt, indem eine durch ein cyclisches Zinnalkoxid ausgelöste ε‐Caprolacton‐Polymerisation mit der Zugabe und anschließenden Polymerisation von wenigen Einheiten α‐(1‐Acryloxyethyl)‐ε‐caprolacton gekoppelt wird. Kaulquappenförmige Polyester mit zwei Schwänzen steuerbarer Länge (siehe Bild) sind auf diese Art einfach zugänglich.

The influence of polymer topology on pharmacokinetics: Differences between cyclic and linear PEGylated poly(acrylic acid) comb polymers

“…[4] Only a few methods can prepare cyclic polymers with this criterion though various ways have explored the synthesis of cyclic polymers. [17, 23–29] Most of the cyclic polymers with narrow polydispersities were prepared by controlled living polymerizations. For example, cyclic [styrene (S)-b-isoprene (I)-b-methyl methacrylate (MMA)] with narrow polydispersity was synthesized under high-dilution conditions by the end-to-end intramolecular amidation reaction of the corresponding linear-α, ω-amino acid precursor [S-b-I-b-MMA] prepared by anionic polymerization.…”

Zwitterionic Polymerization of Lactide to Cyclic Poly(Lactide) by Using N‐Heterocyclic Carbene Organocatalysts

“…[8] In this approach, the metal alkoxide initiator remains in the product at the end of the reaction, although recent strategies have been devised utilizing intramolecular cross-linking and elimination of the tin initiator. [8][9][10] Herein, we report a kinetically controlled synthesis of cyclic polyesters of defined molecular weight and narrow molecular weight distribution by the zwitterionic ring-opening polymerization of lactide with N-heterocyclic carbenes (NHCs). Zwitterionic polymerizations, involving chains with a positively and negatively charged group, have been investigated for many years, [11] but typically yield low-molecularweight linear polymers because of the high reactivity of the cationic and anionic chain ends.…”

Synthetic Strategies towards Well‐Defined Complex Polymeric Architectures through Covalent Chemistry

“…However, one major drawback of this technique is that the tin alkoxide bond present in the resultant cyclic polymer is unstable and readily undergoes hydrolysis. Li et al [193] reported a refined route to overcome the issue of the liable alkoxide bond by introducing a short block of a photocross-linkable lactone with an acrylate side chain into the polyester macrocycles. After UV crosslinking, the initiator can be removed while the integrity of the macrocyclic structure is maintained.…”