Polycaprolactone/Graphene Nanocomposites: Synthesis, Characterization and Mechanical Properties of Electrospun Nanofibers

In this study, three polymer nanocomposites based on poly(e-caprolactone) (PCL) grafted on the graphene quantum dot (GQD), hydroxypropyl cellulose (HPC)/GQD (GQD: HPC = 1:1; w/w) and graphene oxide (GO) with 1.6 wt% of e-caprolactone (CL) were synthesized via in situ ring opening polymerization of CL. The synthesized nanocomposites were characterized using FTIR, 1H NMR, and contact angle measurements. The lowest molecular weight for PCL/GO was obtained according to 1H NMR spectra. Crystalline structure and thermal behavior of composites were investigated by XRD, DSC and TGA. The results showed that the presence of HPC and graphene-based nanofillers in nanocomposite can affect the hydrogen bonding interaction with PCL chains, melting temperature (Tm), degree of crystallinity [Xc(%)] and the size of crystals. According to the results, PCL/GQD-HPC had higher Tm, lower Xc(%), longer PCL moieties and smaller crystals. Also, the TGA results indicated that the nanocomposites were thermally more stable than the pure PCL. Moreover, a conventional electrospinning process was used to prepare nanofibers of synthesized nanocomposites blended with PCL (50:50; w/w). SEM images and mechanical behavior study of obtained nanofibers depicted that the PCL/(PCL/GQD-HPC) nanofibers have a significant increment in the average diameter, tensile modulus and strength in comparison with other composites.