Mechanical characteristics of tunable uniaxial aligned carbon nanotubes induced by robotic extrusion technique for hydrogel nanocomposite

The utilisation of additive manufacturing technique for producing soft hydrogel nanocomposites could enable extraordinary advances in controlling of the material's structure at microscale. A soft gel-printing based on 2-hydroxyethyl methacrylate (HEMA)-based gelation system with embedded uniaxial aligned carbon nanotubes (CNTs), was proposed in this paper. Shear-induced alignment determines the uniform orientation of CNTs during the gel-printing process, thereby introducing tunable mechanical anisotropy into the printed nanocomposite products. Herein, mechanical characterisation in terms of uniaxial tension, dynamic cyclic tension, and numerical simulations have been implemented on the printed samples. The numerical modelling findings, verified by the experimental observations, confidently confirm that the orientation of CNTs significantly impacts the mechanical properties of the nanocomposite, i.e. the ultimate strength, degree of viscoelasticity and strain-rate-sensitivity. Both the gel-printing technique and the anisotropic PHEMA-CNTs nanocomposite will ultimately assist to the rapid manufacture of diverse applications such as flexible electronics or tissue engineering.