Exploring the Role of Superplasticizers in Tailoring the Aqueous Dispersions of Graphene Nanoplatelets

Graphene nanoplatelets (GnPs) exhibit exceptional properties for advanced functional applications; nevertheless, their effective utilization is critically limited by agglomeration and poor dispersion. The incorporation of polycarboxylate-based superplasticizers (SPs) enables improved dispersion yet simultaneously introduces insulating effects that hinder conductive network formation. In the present article, we systematically investigate the interplay between GnPs and an SP under varying ultrasonic energy inputs to optimize dispersion and electrical performance through low-cost suspension processing. Dielectric measurements identify the key parameters governing conductive network formation and reveal the dual role of the SP as both dispersant and electrical barrier. Electrochemical impedance spectroscopy, combined with optical microscopy, provides further insights into the state of dispersion and charge-transport behaviour of the suspensions. For the first time, a wide range of SP and GnP concentrations were systematically analysed in terms of electrical properties. The proposed methodology provides a robust and facile approach for on-site characterization of aqueous suspensions with varying GnPs and SP concentrations. Furthermore, an equivalent circuit model is developed to quantitatively validate the experimental results, offering deeper insights into the underlying conduction mechanisms. GnP concentrations of 0.15, 0.50 and 1.00 wt.% were investigated at varying ratios of SP to GnP (0, 1, 2, 4, and 8). Dispersions without SP addition require ultrasonication up to 80 kJ for the GnP agglomerates to break. SP addition at a quantity equal to GnPs (SP1) reduces the amount of appropriate ultrasonic energy for creating a conductive network up to 65 kJ and even more (SP2) at 45 kJ. The fourfold (SP4) and eightfold (SP8) ratio of SP to GnP require higher ultrasonic energy, up to 82 kJ and 70 kJ, accordingly.