Enhancement on electro-response of gelatin hydrogels with grafted polar groups

In this article, three grafted copolymers, namely gelatin-graft-polypyrrole copolymer (gelatin-g-PPy), gelatin-graft-polyaniline copolymer (gelatin-g-PANI), and gelatin-graft-monomethyl polyethylene glycol copolymer (gelatin-g-MPEG), were successfully synthesized by the introduction of polar groups onto the gelatin matrix. Their chemical compositions were primarily characterized through Fourier Transform Infrared spectroscopy (FT-IR) and Ultraviolet-Visible spectrum (UV-Vis) analyses. The grafted gelatin hydrogels were prepared by utilizing the three grafted gelatin copolymers under an applied electric field ranging from 0 ~ 0.8 kV/mm. The impact of the electric field on the hydrogels was assessed through scanning electron microscopy (SEM), thermogravimetric analysis (TGA), dielectric analysis (DA), and dynamic mechanical analysis (DMA). SEM analysis revealed that the grafted gelatin hydrogels exhibited an ordered microstructure and larger pores when subjected to an electric field. DA testing indicated that all grafted gelatin hydrogels displayed a higher dielectric constant compared to pure gelatin, suggesting an enhanced orientation polarization of the copolymers in response to the electric field. DMA experiments confirmed that, in comparison to pure gelatin hydrogel, all the grafted gelatin hydrogels demonstrated an increased storage modulus in the direction of the applied electric field. The storage modulus increment (ΔG′) and incremental ratio (ΔG′/G′0) of the grafted gelatin hydrogels reached their maximum values at specific grafting levels. These findings suggest that the grafted gelatin hydrogels have excellent electro-responsive property.