Silane functionalization of WS2 nanotubes for interaction with poly(lactic acid)

Eimear Magee; Fengzai Tang; Marc Walker; Alla Zak; Reshef Tenne; Tony McNally

doi:10.1039/d3nr00583f

Silane functionalization of WS₂ nanotubes for interaction with poly(lactic acid)

Nanoscale. 2023 Apr 27;15(16):7577-7590. doi: 10.1039/d3nr00583f.

Authors

Eimear Magee¹, Fengzai Tang², Marc Walker³, Alla Zak⁴, Reshef Tenne⁵, Tony McNally¹

Affiliations

¹ International Institute for Nanocomposites Manufacturing (IINM), University of Warwick, CV4 7AL, UK. t.mcnally@warwick.ac.uk.
² WMG, University of Warwick, CV4 7AL, UK.
³ Department of Physics, University of Warwick, Coventry CV4 7AL, UK.
⁴ Physics Department, Faculty of Sciences, Holon Institute of Technology - HIT, Holon 5810201, Israel.
⁵ Molecular Chemistry and Material Science, Weizmann Institute of Science, Rehovot 76100, Israel.

PMID: 37039126
DOI: 10.1039/d3nr00583f

Abstract

Functionalisation of nanofillers is required for the promotion of strong interfacial interactions with polymers and is essential as a route for the preparation of (nano)composites with superior mechanical properties. Tungsten disulphide nanotubes (WS₂ NTs) were functionalized using (3-aminopropyl) triethoxysilane (APTES) for preparation of composites with poly(lactic acid) (PLA). The WS₂ NTs : APTES ratios used were 1 : 1, 1 : 2 and 1 : 4 WS₂ NTs : APTES. The APTES formed siloxane networks bound to the NTs via surface oxygen and carbon moieties adsorbed on the WS₂ NTs surface, detected by X-ray photoelectron spectroscopy (XPS) studies and chemical mapping using energy dispersive X-ray spectroscopy in the scanning transmission electron microscope (STEM-EDS). The successful silane modification of the WS₂ NTs was clearly evident with both significant peak shifting by as much as 60 cm^-1 for Si-O-Si vibrations (FTIR) and peak broadening of the A_1g band in the Raman spectra of the WS₂ NTs. The evolution of new bands was also observed and are associated with Si-CH₂-CH₂ and, symmetric and assymetric -NH³⁺ deformation modes (FTIR). Further evidence for functionalization was obtained from zeta potential measurements as there was a change in surface charge from negative for pure WS₂ NTs to positive for APTES modified WS₂ NTs. Additionally, the thermal stability of APTES was shifted to much higher temperatures as it was bound to the WS₂ NTs. The APTES modified WS₂ NTs were organophilic and readily dispersed in PLA, while presence of the pendant amine and hydroxyl groups resulted in strong interfacial interactions with the polymer matrix. The inclusion of as little as 0.5 wt% WS₂ NTs modified with 2.0 wt% APTES resulted in an increase of 600% in both the elongation at break (a measure of ductility) and the tensile toughness relative to neat PLA, without impacting the stiffness or strength of the polymer.