Determination of Hansen solubility parameters of halloysite nanotubes and prediction of its compatibility with polyethylene oxide

Abstract

Halloysite nanotubes are extensively studied natural tubular clay mineral that has many potentially important uses in different industrial fields. In this paper, the dispersion behavior of halloysite nanotubes (HNTs) in 22 solvents of different polarities was investigated by dynamic light scattering (DLS) and ultraviolet spectrophotometer (UV). The result revealed that HNTs can be dispersed in solvents with high polar and hydrogen bond component parameters, and the best dispersions were achieved in N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), ethanol (EtOH), and acetonitrile (ACN). Hansen solubility parameters (HSPs) of HNTs were approximately determined of δd = 16.8 MPa1/2, δp = 12.6 MPa1/2 and δh = 17.4 MPa1/2 based on the dispersion state tests. The HSPs of polyethylene oxide (PEO) were further estimated using the group contribution method to predict the compatibility of HNTs and PEO employing HSP theory. The SEM images of the PEO/ HNTs composites with different HNTs content showed that the HNTs were well dispersed in the PEO matrix. Meanwhile, the PEO/HNTs composites exhibited enhanced thermal stability compared to the pure PEO. The results suggested there existed good compatibility between HNTs and PEO and confirmed the usefulness of this approach.