Poly(lactide) (PLA) and its copolymers can be made from naturally occurring materials. They are ideal candidates as sustainable materials to replace the petroleum based polymers. However, these polymers often are brittle so toughening is needed. One of the most effective toughening methods is to reactive blend brittle polymers with materials having very different rigidity. This approach requires that the two materials chemically bond with each other at the interface to compatibilize the blends. Thus, to design and make reactive systems is a key to the success of reactive blending. In this article, we studied toughening poly(lactide‐co‐glycolide) (PLGA) with a rubbery material poly(trimethylene carbonate) (PTMC). We observed that PTMC spontaneously reacted with PLGA during melt blending. The reaction produced PLGA‐co‐PTMC copolymers that stayed at the PLGA/PTMC interface. Those copolymers not only helped to create a stable blend microstructure at a length scale of 100 nm but also promoted the bonding between the PLGA and PTMC domains. It is interesting that the reaction did not need a catalyst or initiator. We speculated that this reaction between PLGA and PTMC was a transesterification reaction. This reaction is easy to achieve and is expected to broaden the property range of the PLGA and other degradable polyesters, enabling them to replace certain types of petroleum based polymers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Poly(lactide) (PLA) and its copolymers degrade through hydrolysis into non-toxic and water soluble metabolic products in vivo. They are ideal materials for resorbable biomedical applications such as drug delivery and tissue engineering. However, these polymers are brittle and often need to be toughened. One of the most effective toughening methods is reactive blending, in which additives are dispersed into polymer matrices as small particles with strong bonding between the two materials. In this paper, we studied toughening poly(lactide-co-glycolide) (PLGA) through reactive blending with poly(trimethylene carbonate) (PTMC). We observed warm-like micelle or swollen warm-like micelle structures created during the reactive blending process with a twin screw extruder at high temperature. The micelle structures were orientated along the extrusion direction with their length ranging from 50 to 1000 nm and diameters about 50 nm. This structure could be produced only with a twin screw extruder. When a batch mixer was used, the PTMC additive (10 to 30 wt%) formed spheres with diameters on the order of 100-500 nm. The PLGA/PTMC copolymers formed in situ were responsible to this microstructure. The mechanical properties of this blend were significantly improved over the pure PLGA.