Additives for Enhancing the Crystallizability and Degradability of Electrospun Poly(l-lactide) Fibers

Abstract

Poly(L-lactide) (PLLA) exhibits a low crystallization rate and a low degree of crystallinity, which limits its use in various applications. In this study, the effects of the addition of poly(ethylene glycol), poly(ethylene adipate), or phthalimide on the thermal and crystallization behaviors of electrospun PLLA fibers were investigated. The additives acted as plasticizers, decreasing the glass transition temperature of PLLA, which resulted in a substantial increase in its degree of crystallinity and a decrease in its crystallite size. Furthermore, the additives decreased the activation energy required for cold crystallization and, thus, increased the rate of cold crystallization kinetics. The various PLLA fibers formed α′ and α crystals, which consisted of loosely and closely packed chain organizations, respectively. During annealing, the α′ crystals gradually transformed into α crystals, and the additives accelerated this polymorphic transition. Furthermore, the presence of additives made the PLLA susceptible to alkaline degradation, which resulted in an increase in the degradation rate of the PLLA/additive fibers compared with that of neat PLLA fibers.