Characterization of novel thermoresponsive poly(butylene adipate-co-terephthalate)/poly(N-isopropylacrylamide) electrospun fibers

Abstract

In this work, electrospun fibers of poly(butylene adipate-co-terephthalate) (PBAT) and poly(N-isopropylacrylamide) (PNIPAAm) blends, PBAT/PNIPAAm, with different mass ratios, were obtained. For characterization of their morphological, structural, thermal and wettability properties, scanning electron microscopy (SEM), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetry (TG), differential scanning calorimetry (DSC) and drop water contact angle (DWCA) measurements were carried out. The optimum conditions determined for electrospinning were: voltage of 25 kV, flow rate of 1.3 mL·h−1 and working distance of 15 cm. The most important result was achieving PBAT/PNIPAAm electrospun fibers with a thermoresponsive behavior and a sudden response to temperature at PNIPAAm’s LCST (lower critical solution temperature). From SEM analysis, the higher the content of PNIPAAm in the blend, the higher the average diameter of the electrospun fibers was; also, the higher content of PNIPAAm in the blend allowed the fibers to be rounded with no presence of beads. From ATR-FTIR analysis, no formation of strong intermolecular interactions, such as hydrogen bonding, between the PBAT and PNIPAAm chains was observed. From TG and DSC analyses, the thermal stability of the PBAT/PNIPAAm fibers remained unchanged in respect to the electrospinning. DWCA measurements for PBAT/PNIPAAm 70/30 and 50/50 fibers, in response to temperature, indicated a gap of 50° to 60° at PNIPAAm’s LCST, evidencing their high thermosensitivity. With these results, PBAT/PNIPAAm electrospun fibers with 30% or more in mass ratio of PNIPAAm might find a potential application for the cell adhesion/detachment field.