Abstract:

Objective Waterborne polyurethane fabric finishing agents are limited in their applications due to their poor hydrophobicity and electrical conductivity. This study aims to enhance the hydrophobicity, mechanical properties and electrical conductivity of waterborne polyurethane by incorporating functionalized graphene oxide. The goal is to create a multifunctional waterborne polyurethane fabric finishing agent that can expand its range of applications.

Method Functionalized graphene oxide (MPD-I-GO) was synthesized by sequentially reacting isophorone diisocyanate (IPDI) and m-phenylenediamine (MPD) with graphene oxide (GO). MPD-I-GO was then incorporated into waterborne polyurethane(WPU) at a specific mass fraction to produce an MPD-I-GO/WPU fabric coating. The chemical structure, crystallinity and microscopic morphology of MPD-I-GO were characterized using infrared spectroscopy, Raman spectroscopy, X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. Additionally, the hydrophobicity, mechanical properties and electrical conductivity of the composite films were evaluated and analyzed using a surface wetting angle meter, universal tensile tester and four-probe conductivity meter.

Results The MPD was introduced into the GO surface with IPDI as a bridge to make MPD-I-GO (Fig. 2). It also intercalates into the GO sheet layer, making part of the layer spacing increase and disorder increase (Fig. 3 and Fig. 4). When the MPD-GO addition is 0.18% and below, the composite latex particles were spherical with uniform sizes and were evenly distributed with no aggolomeration, and the average particle size was about 44.77 nm (Fig. 7 and Fig. 8). The contact angle of the composite latex membrabe showed an increasing trend with the increase of MPD-I-GO mass fraction (Fig. 10), and when MPD-I-GO was added, wrinkles appeared in the cross section of the composite latex membrane and became more and more obvious with the increase of MPD-I-GO mass fraction (Fig. 12). The addition of MPD-I-GO significantly improved the mechanical properties of WPU (Fig. 13). The resistivity of the composite latex membrane decreased significantly after the addition of MPD-I-GO, and with the increase of the mass fraction of MPD-I-GO the resistivity of the composite latex membrane all showed a trend of first decreasing and then increasing, and reaching the minimum value of 205 Ω/cm at 0.18% (Fig. 14).

Conclusion In this work, MPD-I-GO was prepared by modifying GO with IPDI and MPD successively and introduced into WPU, and the effect of mass fraction of MPD-I-GO on the properties of composite adhesive films was investigated. The study showed that IPDI and MPD were successfully grafted onto GO without completely destroying the lamellar structure of GO. In addition, when the addition amount of MPD-I-GO was below 0.18%, MPD-I-GO could be uniformly dispersed in WPU and effectively promoted the improvement of hydrophobicity, mechanical properties and electrical conductivity at the same time. The introduction of MPD-I-GO improved the roughness of the surface of the latex film, thus improving the hydrophobicity of the composite at the structural level. This indicates that the introduction of MPD-I-GO can effectively enhance the performance of WPU and promote the functionalized application of waterborne polyurethane fabric finishing agents.

Key words: water-based polyurethane, functionalized graphene, composite coating, hydrophobicity, antistatic properties