Enhanced nonlinearites of functionalized single wall carbon nanotubes with diethynylsilane derivatives

► DFT first hyperpolarizability (β) for functionalized carbon nanotubes are reported. ► PDES decamers were introduced longitudinally and transversely to nanotube surface. ► Enhanced β values (>1000 × 10−30 cm5 esu−1) were obtained for all substituted CNTs. ► The largest β is 21 991 × 10−30 cm5 esu−1, undoubtedly a stimulating remarkable value. ► Oligomer nanocomposites are prominent candidates as nonlinear second-order materials.