Control on molecular weight reduction of poly(ε-caprolactone) during melt spinning--a way to produce high strength biodegradable fibers.

Poly(ε-caprolactone) (PCL) is known for its biocompatibility and biodegradability. These features of PCL have resulted into significant academic as well as industrial research interests for use of this polymer in various areas including biomedical and tissue engineering. Three-dimensional porous scaffolds, controlled drug release systems and nerve guides are some of the forms in which this polymer has been used. Despite these forms, fibers made of PCL have not gained much attention due to PCL's low melting point (57-60 °C) and relatively inferior mechanical properties as compared to poly(L-lactide) (PLA). Also the polymer is sensitive to the process conditions of melt spinning which leads to degradation of PCL when subjected to high temperatures in the presence of air or moisture. Here we present an approach in which addition of a bilactone, bis-(ε-caprolactone-4-yl) (BCY), during melt spinning of PCL resulted into monofilament fibers having tenacity as high as 2500 MPa. The cross-linking of PCL which occurred due to BCY transesterification compensated for molecular weight reduction of the polymer under melt spinning conditions. PCL monofilament fibers thus developed have enhanced thermo-mechanical properties and therefore have high potential to be used in tissue engineering applications in the form of sutures, a mesh or a non-woven.