Poly(epsilon-caprolactones) (PCLs) belong to the first generation of synthetic aliphatic polyesters. Their biodegradability motivated their extensive exploration as resorbable materials, particularly in controlled drug release applications. While PCL fell out of fashion due to the increasing popularity of shorter chain polyglycolides and derivatives, there has been a noticeable renewed interest in epsilon-caprolactone derived components for copolymer systems with advanced functions in the last decade or so. PCL has particular properties that are attractive for the design of tunable biomaterials such as slow crystallization kinetics and low melting temperatures in the physiological range. Slow degradation rates, with relatively minimal acid generation, can be valuable for prolonged drug release or longer-term stability of implants. Herein we cover recent developments of PCL chemistry, focussing on innovative uses of epsilon-caprolactone-based segments in sophisticated polymer architectures such as multiblock copolymer networks, and micellar systems. Such polymer constructs are of high interest for biomedical applications. (c) 2013 Elsevier Ltd. All rights reserved.