Self-reinforcing nanoscalar polycaprolactone-polyethylene terephthalate electrospun fiber blends

Abstract

Blends of polycaprolactone (PCL) and polyethylene terephthalate (PET) - both widely used biocompatible polymers – could have applications in long-term drug delivery. To avoid PCL degradation characteristic of hot extrusion of this blend, we utilize phase separation of PET during electrospinning of PCL-PET blends followed by heating to 120 °C during which the PCL component eliminates porosity. The resulting crystallized PET nanofiber follows the spatial arrangement of the initially deposited electrospun PCL-PET fibers. This increased the modulus of the PCL by 38% while elongation to break and ultimate tensile strength (UTS) remain unaffected. These sintered 25:75 PET-PCL blends maintained their mechanical properties at least three months in 37 °C PBS and >3 months in 37 °C DMSO. Differential scanning calorimetry and X-ray diffraction confirm that increased brittleness is caused by increases in PCL crystallinity. Controlled phase separation to achieve directed composite formation could utilize other polymers and optimized fiber deposition to catalyze further mechanical property improvements.