Functionalized Multiwalled Carbon Nanotubes Improve Piezoelectric and Biological Performances of the PVDF–TrFE/ZnO Electrospun Fiber Film

Piezoelectric materials can actively provide a bioelectric microenvironment by converting mechanical stimulations into electrical signals. Combining the excellent flexibility of piezoelectric polymers and the outstanding piezoelectric properties of piezoelectric ceramics, piezoelectric composites are attractive in tissue repair due to their high response to micromechanical stimulations. However, issues such as agglomeration, dielectric differences, and poor interfacial contact with polymers have limited the role of ceramics in improving the overall properties of the composites. In this work, functionalized multiwalled carbon nanotubes (F-MWCNTs) are applied to disperse zinc oxide (ZnO) in the PVDF–TrFE matrix to prepare electrospun composite fiber films. Through the assistance of hydrogen bonding, F-MWCNTs act as bridges connecting ZnO nanoparticles with PVDF–TrFE, which improves the content and crystallinity of the β phase. Furthermore, this strategy enhances the local electric field and reduces dielectric differences, resulting in improved polarization and piezoelectric properties. Results show that the composite fiber film with 0.35 wt % F-MWCNTs could obtain an open-circuit voltage of up to 8.2 V, a β phase content of 83.36%, and a crystallinity of 57.63%. Meanwhile, due to the synergistic effect of F-MWCNTs and ZnO, the tensile strength and Young’s modulus are increased from 3.5 and 11.0 to 6.6 and 19.49 MPa, respectively. Additionally, cellular experiments show that composite fiber films have good bioactivity and promote cell proliferation and adhesion, especially with 0.35 wt % F-MWCNTs. In conclusion, the composite fiber film possesses good piezoelectric and mechanical properties and enhances the cellular activity, making it a good tissue engineering scaffold.