Branched aliphatic polyesters by ring-opening (co)polymerization

The rapid development of biodegradable and biocompatible materials for biomedical applications is reflected in the search for new methods for aliphatic polyester modification applicable in this field. One possible approach is modification by changes to the polymer topology.This review covers the main methods of synthesis of branched aliphatic biodegradable and biocompatible (co)polyesters, where the ring-opening polymerization (ROP) of cyclic esters or cyclic carbonates is the leading process. First, literature examples of ring-opening multibranching polymerization (ROMBP) of AB2-type hydroxyl-substituted cyclic lactones, lactides and carbonates are cited followed by the presentation of the application of AB-type cyclic esters and additionally AB2 cyclic ethers or esters as “branching monomers” for the synthesis of branched polyesters based on polycaprolactone (PCL), polylactide (PLA) and polyglycolide (PGA). In the following part, methods involving the combination of the ROP of AB-type cyclic esters and condensation processes leading to branched structures are summarized. Other related strategies leading to “dendri-star” or “core-shell” copolyesters are also discussed. Several examples of approaches to PCL and PLA graft copolymer syntheses are also shown. The advantages and disadvantages of the presented methodologies of branched polyester synthesis are highlighted. Finally, the influence of the branched structure on the properties of the presented class of polyesters, important from the application point of view, is considered.