Fig. 4: Mechanical properties of PBDT + GO nanocomposites.

a The enhancement in storage modulus (E’) from dynamic mechanical thermal analysis for PBDT + GO nanocomposites (denoted by filled blue squares). The differences between the maximum film modulus of GO nanocomposites (E_NC) and the corresponding values of polymer matrix modulus (E_PM), ΔE, is tabulated for literature data for different classes of polymers (aliphatic, semi-aromatic, and aromatic denoted by open-turquoise circles, open blue triangles and orange squares respectively) reported for either dynamic thermo-mechanical analysis (E’) or tensile measurements (E) of films. Theoretical estimate for ΔE was calculated from the rule of mixtures³ using densities of 1.4 and 2.0 g.cm⁻³ for PBDT and GO respectively, E_GO = 250 GPa, GO aspect ratio = 3500 and perfect in-plane orientation within the nanocomposite; ΔE is invariant for E_PM values in the 0.1–10 GPa. For PBDT + GO nanocomposites, the ΔE strongly depends on C_total of the hybrid film casting mixture; ΔE = 23 GPa is obtained for PBDT + GO films when cast from C_total = 7.1 wt.%. Optical microscopy images of nanocomposites also indicate that GO dispersion quality is also dependent on C_total. The scale bar (200 µm) is the same for both optical microscopy images. b Strength enhancement from tensile stress-stress measurements. The Y-error bar represents the standard deviation from the average. The enhancement Δσ = (σ_NC − σ_PM) is the difference between the nanocomposite’s maximum tensile strength (σ_NC) and that of the polymer matrix (σ_PM); while σ_NC is dependent on the GO loading, Δσ does not show any significant correlation with GO content. Reported Δσ values for GO-polymer nanocomposites are indicated for optimum GO loadings for a variety of polymer matrices (see Supplementary Data 1); for PBDT + GO nanocomposite cast from C_total = 4.9 wt.% ^hN_b mixture, Δσ = 320 MPa.