Highly resilient antibacterial composite polyvinyl alcohol hydrogels reinforced with CNT-NZnO by forming a network of hydrogen and coordination bonding

Carbon nanotube-doped nano-zinc oxide (CNT-NZnO) was used to reinforce polyvinyl alcohol (PVA) by creating a network consisting of hydrogen and coordination bonding. Composite PVA/CNT-NZnO hydrogels were prepared through ultrasonic solution blending, freezing–thawing cycles, and their mechanical properties, water content, gel fraction, swelling ratio, crystallinity, thermal stability, and antibacterial activity were studied. The composites were characterized using Fourier transform infrared (FTIR) spectroscopy, field emission electron scanning microscopy (FESEM), energy X-ray spectroscopy (EDS), and X-ray diffraction (XRD). When the CNT-NZnO content was increased from 0 to 0.6 phr, the tensile strength greatly increased from 1.1 to 2.3 MPa. Relative to pure PVA hydrogel, composite PVA/CNT-NZnO hyrogels showed increased tensile strength (by 109.1%). Their elongation at break increased from 191.1 to 373.9%, an increase by 182.8% with pure PVA hydrogel as reference. The results of FTIR analysis showed that PVA formed a coordination reaction with CNT-NZnO, synergistically improving the tensile strength of PVA. EDS test analysis showed that of all the filler content considered in this study, 0.6 phr CNT-NZnO was uniformly distributed in the PVA hydrogel the most. The results of XRD analysis showed that when the content of CNT-NZnO was ≤ 0.6 phr, the crystallinity decrased, indicating that the nanofillers were evenly dispersed. When the content was > 0.6 phr, the crystallinity significantly increased, indicating the the nanofillers were not be dispersed well, and agglomeration occurred. The results of SEM analysis showed that the addition of a small amount of CNT-NZnO changed the microstructure of the PVA hydrogel, making the three-dimensional network structure of the composite gel more compact. In addition, CNT-NZnO enhanced the hydrophobicity, dye adsorption, and gave good antibacterial properties to the hydrogels. The new antibacterial composite hydrogel with dye adsorption capacity had excellent mechanical properties and shape recovery ability, and had potential applications in the field of biomedical materials.