Functionalized Multiwalled\nCarbon Nanotubes Improve\nPiezoelectric and Biological Performances of the PVDF–TrFE/ZnO\nElectrospun Fiber Film

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