Surfactant-Free Stabilization of Aqueous Graphene Dispersions Using Starch as a Dispersing Agent

Abstract

Attention to graphene dispersions in water with the aid of natural polymers is increasing with improved awareness of sustainability. However, the function of biopolymers that can act as dispersing agents in graphene dispersions is not well understood. In particular, the use of starch to disperse pristine graphene materials deserves further investigation. Here, we report the processing conditions of aqueous graphene dispersions using unmodified starch. We have found that the graphene content of the starch–graphene dispersion is dependent on the starch fraction. The starch–graphene sheets are few-layer graphene with a lateral size of 3.2 μm. Furthermore, topographical images of these starch–graphene sheets confirm the adsorption of starch nanoparticles with a height around 5 nm on the graphene surface. The adsorbed starch nanoparticles are ascribed to extend the storage time of the starch–graphene dispersion up to 1 month compared to spontaneous aggregation in a nonstabilized graphene dispersion without starch. Moreover, the ability to retain water by starch is reduced in the presence of graphene, likely due to environmental changes in the hydroxyl groups responsible for starch–water interactions. These findings demonstrate that starch can disperse graphene with a low oxygen content in water. The aqueous starch–graphene dispersion provides tremendous opportunities for environmental-friendly packaging applications.

Application of Polymers for Chemical Enhanced Oil Recovery: A Review

“…Iqbal et al [ 167 ] recorded high stability and better colloidal stability of iron oxide nanoparticles at high temperature (120 °C) via electrosteric stabilization using poly(AMPS-co-AA) copolymer. Zhao et al [ 168 ] reported the good stability of PNF composed of starch and graphene nanoparticles. Similarly, Vasconcelos et al [ 169 ] observed that ethylenediamine-modified graphene oxide nanoparticles exhibited good stability properties after aging for 90 days, with 146% higher viscosity over HPAM.…”

Highly Conductive Films by Rapid Photonic Annealing of Inkjet Printable Starch–Graphene Ink

“…[14] In recent years, graphene nano-sheets, a 2D network of sp 2 -hybridized carbon atoms in a hexagonal configuration, have captured immense attention as an alternative conductive ink owing to its exceptional combination of mechanical, thermal, optical, and electronic properties. [14][15][16][17][18][19][20] Formulating inkjet printable graphene ink is generally challenging since the inkjet printing method requires the ink to have specific range of values for the properties such as flake size, surface energy, viscosity, and density. [6,14] The inks mostly require additional surfactants and binders for stabilization that must be removed after the printing process by post-treatment methods in order to attain the desired properties.…”

“…[3,[7][8][9][10][11][12][13] However, the actual material choice of the ink for a particular application is dictated by several factors including nanoparticles as dispersing agent. [19] Starch is produced from plant-based sources on a large scale and used in numerous industrial sectors, such as food, papermaking, and pharmaceuticals. [24] The abundant, biodegradable, and renewable nature of starch paves the way for production of eco-friendly graphene ink.…”

“…[ 21 ] Additionally, the use of commercial synthetic surfactants and their decomposed by‐products in the environment have adverse effects on the ecosystem. [ 19 ] Therefore, the formulation of a commercial synthetic surfactant‐free graphene ink and the use of an annealing method that is suitable for heat‐sensitive substrates are necessary. These needs create the context for the study presented here.…”

“…Here, we started from our previous work on demonstrating surfactant‐free stabilization of aqueous graphene dispersions using starch as dispersing agent, [ 19 ] and reworked the formulation to inkjet printable graphene ink and investigated the annealing process using the photonic sintering method. Figure a shows the formulated starch–graphene ink inside a vial and AFM (top‐right) and bright field‐STEM (bottom‐right) images of a starch–graphene sheet prior to size reduction.…”