Water-soluble polyvinyl alcohol composite films with nanodiamond particles modified with polyethyleneimine

Abstract

With the enhancement of people's awareness of environmental protection, polyvinyl alcohol (PVA), a water-soluble environmental protection material with good biodegradation performance and innocuity, has attracted more and more attention. In view of the performance defects of PVA, this paper uses environmentally friendly nanodiamond (ND) particles to improve PVA's properties. First, the ND particles oxidized with air were coated with dopamine and then reacted with polyethyleneimine (PEI) to obtain hydrophilic ND-NH₂ particles. Infrared spectroscopy and Raman spectroscopy analysis showed that PEI formed covalent bonds on the ND surfaces. The dispersion stability analysis showed that the dispersion stability of the ND particles improved. The grafting rate of the ND-NH₂ particles reached the maximum of 6.01%, suggested by TGA. In order to decrease the agglomeration of ND particles and enhance the interfacial compatibility between the ND particles and PVA matrix, different contents of the above obtained ND-NH₂ particles were added to the PVA matrix to prepare a series of ND-NH₂/PVA composite films. Pure PVA films and PVA composite films were prepared by the solution casting method. When the amount of ND-NH₂ particles added was 1.0%, the thermal conductivity of the composite film was 0.2544 W m⁻¹ K⁻¹, which was 148.20% higher than that of the pure PVA film, and the tensile strength of the composite film reached the maximum (73.00 MPa), 113.45% higher than that of the pure PVA film.