Graphene-doped photo-patternable ionogels: tuning of conductivity and mechanical stability of 3D microstructures

Abstract

This work reports for the first time the development of enhanced conductivity, graphenedoped photo-patternable hybrid organic-inorganic ionogels and the effect of the subsequent materials condensation on the conductivity and mechanical stability of threedimensional microstructures fabricated by multi-photon polymerisation (MPP). Ionogels were based on photocurable silicon/zirconium hybrid sol-gel materials and phosphonium (trihexyltetradecylphosphonium dicyanamide [P6,6,6,14][DCA] ionic liquid (IL). To optimise the dispersion of graphene within the ionogel matrices, aqueous solutions of graphene were prepared, as opposed to the conventional graphene powder approach, and employed as catalysts of hydrolysis and condensation reactions occurring in the sol-gel process.Ionogels were prepared via a two step process by varying the hydrolysis degree from 25 to 50%, IL content between 0-50 w/w%, and the inorganic modifier (zirconate complex) concentration from 30 to 60 mol.% against the photocurable ormosil and they were characterised via Raman, Electrochemical Impedance Spectroscopy and Transmission Electron Microscopy. MPP was performed on the hybrid ionogels, resulting in threedimensional microstructures that were characterised using scanning electron microscopy.It is clearly demonstrated that the molecular formulation of the ionogels, including the concentration of graphene and the zirconate network modifier, play a critical role in the conductivity of the ionogels and influence the resulting mechanical stability of the fabricated three-dimensional microstructures. This work aims to establish for the first time the relationship between the molecular design and condensation of materials in the physico-chemistry and dynamic of ionogels.3

Effect of the condensation of hybrid organic–inorganic sol–gel materials on the optical properties of tripan blue

“…In fact, the main difference between these materials resides in the degree of chelation of the zirconium atom, the role of which has been identified in previous studies in catalysing the formation of siloxane bonds and participating to the formation of the inorganic backbone of the material [11][12][13]. In material A, the ligand is added in a stoichiometric ratio against the zirconium precursor, resulting in preventing 50% of its propoxide groups to undergo hydrolysis and further participate to the condensation reactions.…”

3D Assembly of Graphene Nanomaterials for Advanced Electronics

“…Doping ionogels with graphene in varying concentrations leads to condensed materials displaying higher conductivity. This underlying mechanism was attributed to decreased pore volume and internal surface area, which results in better interaction between ionogels and graphene . Most of these devices are fabricated using multistep and low‐yield processes such as free‐form and micromolding .…”

Additive Manufacturing: Applications and Directions in Photonics and Optoelectronics

“…Examples are metal alkoxides, [67,68] nonlinear optical molecules, [69] QDs, [70] and conducting ionogels and graphene. [71] The most widely used hybrid materials are the silicate OrmoComp (and its different formulations) developed by the Fraunhofer Institute of Silicate Research [72] and commercially supplied by Microresist Technology, [73] and the zirconium silicate SZ2080. [74][75][76][77][78] Examples of 3D components made by the latter material are shown in Figure 3a,b.…”