Noncovalently Functionalized Tungsten Disulfide Nanosheets for Enhanced Mechanical and Thermal Properties of Epoxy Nanocomposites

Abstract

In the present study, noncovalently functionalized tungsten disulfide (WS) nanosheets were used as a toughening agent for epoxy nanocomposites. WS was modified with branched polyethyleneimine (PEI) to increase the degree of interaction of nanosheets with the epoxy matrix and prevent restacking and agglomeration of the sheets in the epoxy matrix. The functionalization of WS sheets was confirmed through Fourier transform infrared spectroscopy and thermogravimetric analysis. The exfoliation of the bulk WS was confirmed through X-ray diffraction and various microscopic techniques. Epoxy nanocomposites containing up to 1 wt % of WS-PEI nanosheets were fabricated. They showed a remarkable improvement in fracture toughness (K). K increased from 0.94 to 1.72 MPa m for WS-PEI nanosheet loadings as low as 0.25 wt %. Compressive and flexural properties also showed a significant improvement as incorporation of 0.25 wt % of WS-PEI nanosheets resulted in 43 and 65% increase in the compressive and flexural strengths of epoxy nanocomposites, respectively, compared with neat epoxy. Thermal stability and thermomechanical properties of the WS-PEI-modified epoxy also showed a significant improvement. The simultaneous improvement in the mechanical and thermal properties could be attributed to the good dispersion of WS-PEI nanosheets in the matrix, intrinsic high strength and thermal properties of the nanosheets, and improved interaction of the WS nanosheets with the epoxy matrix owing to the presence of PEI molecules on the surface of the WS nanosheets.

Nanocomposite of Poly(l-Lactic Acid) with Inorganic Nanotubes of WS2

“…This fact suggests that suitable surface modifications of the nanotubes can produce a more intimate and stronger nanotube-polymer interactions. There are several reports on the functionalization of nanoparticles in the literature, using N-Methyl-2-pyrrolidone (NMP) [39][40][41][42], polyethylenimine (PEI) [43,44], polyethylene glycol (PEG) [45][46][47][48][49], and more. NMP, PEI, and PEG are well-known dispersants for nanoparticles in various matrices [43,50].…”

Amino Functionalization of Reduced Graphene Oxide/Tungsten Disulfide Hybrids and Their Bismaleimide Composites with Enhanced Mechanical Properties

“…Rarely have previous studies achieved such remarkable improvements in the flexural and impact strength of graphene-based nanoparticle-modified BMI or other resins with trace amounts of fillers. Some previous works have been listed in Table 1; to the best of our knowledge, the comparatively optimal flexural and impact strength of graphene-based nanoparticle-modified BMI, or other resins among these studies, were 163 MPa and 19.15 kJ/m 2 , respectively [4,15,16,17,32,33,34]. Thus, the results of the present work are comparable to that of previous works, indicating the NH 2 -rGO/WS 2 nanoparticles play a vital role in elevating the mechanical properties of the BMI resin.…”

Preparation of polyvinyl alcohol/two‐dimensional transition metal dichalcogenides composites by high‐pressure homogenization

“…Similar phenomena occurred in the literature. 45,46 There was a clear right shift of the curve of the composite materials compared to pure PVA sample. At low temperature stage, the curve of the composite materials almost overlapped with that of pure PVA and an obvious right shift appeared at the high temperature stage (higher than 360 C), T 90% was chosen to measure the stability at high-temperature stage.…”