Poly(furfuryl alcohol)-Polycaprolactone Blends

Abstract

Poly(furfuryl alcohol) (PFA) is a bioresin synthesized from furfuryl alcohol (FA) that is derived from renewable saccharide-rich biomass. In this study, we compounded this bioresin with polycaprolactone (PCL) for the first time, introducing new functional polymer blends. Although PCL is biodegradable, its production relies on petroleum precursors such as cyclohexanone oils. With the method proposed herein, this dependence on petroleum-derived precursors/monomers is reduced by using PFA without significantly modifying some important properties of the PCL. Polymer blend films were produced by simple solvent casting. The blends were characterized in terms of surface topography by atomic force microscopy (AFM), chemical interactions between PCL and PFA by attenuated total reflection-Fourier transform infrared (ATR-FTIR), crystallinity by XRD, thermal properties by differential scanning calorimetry (DSC), and mechanical properties by tensile tests and biocompatibility by direct and indirect toxicity tests. PFA was found to improve the gas barrier properties of PCL without compromising its mechanical properties, and it demonstrated sustained antioxidant effect with excellent biocompatibility. Our results indicate that these new blends can be potentially used in diverse applications ranging from food packing to biomedical devices.

Keywords: antioxidant polymer; biocompatibility; food packaging; poly(furfuryl alcohol); polycaprolactone.

Figure 1

(a) Photographs of polymer solutions of polycaprolactone (PCL) and poly(furfuryl alcohol) (PFA) resin dissolved in dichloromethane (DCM) containing different PFA concentrations; (b) photographs of the blend films obtained after casting the solutions and drying. The films have a thickness of approximately 100 μm and a diameter of 3 cm. Atomic force microscopy (AFM) images and 3D rendering of (c) a PCL film and (d) a 50/50 blend film. The AFM images are 10 μm × 10 μm in size.

Figure 2

Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectra of pure PCL and PFA resin as well as blend films. The band assignments of PCL (black) and PFA (red) as well as the chemical structures of both substances are included.

Figure 3

(a) Melting temperature and percent crystallinity for PCL and different PCL/PFA blends measured by DSC and XRD, respectively. Mass loss curves (b) and derivatives of each curve (c) for PFA, PCL and different PCL/PFA blends measured by TGA.

Scheme 1

Thermal degradation mechanisms of PCL (top panel). Reproduced with permission from American Chemical Society [36]. Thermal degradation mechanisms of PFA (bottom panel). Reproduced with permission from Elsevier [35].

Figure 4

Representative stress-strain curves (a), elastic modulus (b), and elongation at break (c) of neat PCL and blends at different PCL/PFA proportions.

Figure 5

Confocal images of CHO cells growing on 50/50 PCL/PFA (a) and 70/30 PCL/PFA (b). Nuclei are labeled with DAPI (4′,6-Diamidino-2-phenylindole dihydrochloride, blue) and cytoskeleton is labeled with Alexa-Fluor Phalloidin (green). The cells morphology is healthy. The real-time proliferation curves are displayed in panel (c). On PCL/PFA, cells reached confluence after 48 h. The growth rate decreased compared to control, where cells built multilayers (see Figure S2), as the multistep curve indicates.

Figure 6

(a) Change in the absorption spectra upon reaction of 2,2-diphenyl-1-picrylhydrazyl (DPPH•) with a 70/30 sample. (b) Loss of the characteristic deep violet color of the DPPH• solution after being in contact with different samples for 24 h. (c) Radical scavenging activity of PCL and PCL/PFA blends tested against DPPH• in a spectrophotometric assay.

Figure 7

Oxygen transmission rate of neat PCL and PCL/PFA blends in 95/5, 90/10, 70/30 and 50/50 proportions.