Revisiting the pristine carbon nanotubes as dienophile: A promising crosslinking agent to build the inorganic-organic network for polybutadiene based on dynamic crosslinked mode

In this paper, the pristine carbon nanotubes (CNTs) could directly act as dienophile and furan modified polybutadiene elastomer could be used as macromolecular diene to take part in the formation of inorganic-organic network via Diels-Alder reaction, which was quite a convenient and original method. The success of the crosslinking reaction was assessed by swelling measurements and the chemical structure and morphologies of carbon nanotubes in the hybrid were confirmed via Raman, FT-IR, SEM and TEM. Via this simple method, the final hybrid materials could be only swollen in the toluene at room temperature, which indicated that the pristine CNTs could really act as inorganic crosslinking agents toward the furan modified polybutadiene elastomer. The mechanical properties of this series of hybrid could be tailored by the content of CNTs and furan grafting ratio. For example, with increasing the content of CNTs up to 20%, the modulus could be increased from 3.58 to 13.20 MPa for PB-30Fu-yCNTs series. Due to the dynamic nature of DA reaction, the CNTs could be successfully recycled and the crosslinked hybrid films could also be remolded by solution casting method via retra-DA reaction. In this way, the service life for this kind of crosslinked hybrids could be prolonged in a sustainable way, which is quite different from the conventional method to produce carbon nanotubes-polymer hybrids.