Microstructural and physicochemical characterization of solution blow spinning PMMA microfiber/ rGO nanocomposite

Polymethyl methacrylate (PMMA) microfiber nanocomposites containing 0.5, 1.0, and 2.0 wt% reduced graphene oxide (rGO) were produced by solution blow spinning (SBS). These novel nanocomposites were evaluated for their morphological, microstructural, thermal, and physicochemical properties. Scanning Electron Microscopy (SEM) analysis revealed a non-linear evolution of fiber diameter with increasing rGO content: the mean diameter increased from 1.12 μm (neat PMMA) to 1.30 μm at 0.5 wt%, then decreased to 0.62 and 0.55 μm at 1.0 and 2.0 wt%, respectively, while rGO nanosheets became increasingly visible along the fiber length at higher loadings. The rGO exhibited a disordered graphitic structure (ID/IG = 1.31), a specific surface area of 158 m 2 /g, and a total pore volume of 1.1 cm 3 /g, consistent with the sheet-stacking nanometric morphology observed by Transmission Electron Microscopy (TEM) and supporting the aggregation behavior identified by SEM at higher loadings. Thermogravimetric Analysis (TGA) showed that the PMMA chain-depolymerization mechanism was retained across all compositions, with Tonset varying 3 °C and Tmax by less than 4 °C, while Differential Scanning Calorimetry (DSC) confirmed that Tg remained invariant within 1.2 °C, corroborating the noncovalent nature of the polymer–filler interactions. X-ray Diffraction (XRD), Raman spectroscopy, and Fourier-Transform Infrared Spectroscopy (FTIR) presented a consistent picture in which rGO acts as a physically interacting, structurally disordered nanofiller, with no evidence of covalent bonding, polymer intercalation, or chemical modification of the PMMA backbone. These results indicate that the premixed SBS route enables loading-dependent control of microfiber morphology while preserving the physicochemical integrity of the PMMA matrix.