Unique Halloysite Nanotubes-Polyvinyl Alcohol-Polyvinylpyrrolidone Composite Complemented with Physico-Chemical Characterization

A halloysite nanotubes-polyvinyl alcohol-polyvinylpyrrolidone (HNTs-PVA-PVP) composite has been investigated for a quite long time aiming at improving the physico-chemical characterization of HNTs. In this work, HNTs-PVA-PVP composite were prepared based on a unique procedure characterized by crosslinking two polymers with HNTs. The composite of two polymers were modified by treating HNTs with phosphoric acid (H3PO4) and by using malonic acid (MA) as a crosslinker. The composite was also treated by adding the dispersion agent sodium dodecyl sulfate (SDS). The HNTs-PVA-PVP composite shows better characteristics regarding agglomeration when HNTs is treated in advance by H3PO4. Fourier transforminfrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electronmicroscopy (TEM), field emission scanning electronmicroscopy (FESEM), brunauer-emmett-teller (BET), size distribution, and atomic force microscopy (AFM) are used to characterize the physio-chemical properties of the composite. FTIR shows additional peaks at 2924.29, 1455.7, and 682.4 cm(-1) compared to the neat HNTs due to adding MA. Despite that, the XRD spectra do not show a significant difference, the decrease in peak intensity could be attributed to the addition of semi-crystalline PVA and the amorphous PVP. The images taken by TEM and FESEM show the possible effects of MA on the morphology and internal feature of HNTs-PVA-PVP composite treated by MA by showing the deformation of the matrix. The BET surface area increased to 121.1 m(2)/g compared to the neat HNTs at 59.1 m(2)/g. This result, the second highest recorded result, is considered a breakthrough in enhancing the properties of HNTs-PVA-PVP composite, and treatment by MA crosslinking may attribute to the size and the number of the pores. The results from these techniques clearly showed that a significant change has occurred for treated HNTs-PVA-PVP composite where MA was added. The characterization of HNTs-PVA-PVP composite with and without treating HNTs and using crosslinker may lead to a better understanding of this new composites as a precursor to possible applications in the dentistry field.