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

In this study, three polymer nanocomposites based on poly(epsilon-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 epsilon-caprolactone (CL) were synthesized via in situ ring opening polymerization of CL. The synthesized nanocomposites were characterized using FTIR, H-1 NMR, and contact angle measurements. The lowest molecular weight for PCL/GO was obtained according to H-1 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 (T-m), degree of crystallinity [X-c(%)] and the size of crystals. According to the results, PCL/GQD-HPC had higher T-m, lower X-c(%), 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.