Graduation and master's degree in Computing. Currently, PhD student and member of the Research Group on Intelligent Macromolecules (SMaRT) in the PPGCEM / UFSCAR program, with an interest in the research lines of electroactive polymers, composites, actuators, artificial muscles, computer vision and machine learning.
RESEARCH, TEACHING, or OTHER INTERESTS
Information Systems, Materials Science, Multidisciplinary, Computer Vision and Pattern Recognition
Processing methods and vulcanization influence on the electrical and mechanical behavior of isoprene rubber/MWCNT composites Roger Gonçalves, Kaique A Tozzi, Rafael Barbosa, Carlos HM Fernandes, Matheus C Saccardo, et al. Progress in Rubber Plastics and Recycling Technology, 2025 The burgeoning electronics industry demands flexible and cost-effective electrodes. Despite their inherent insulating nature, conductive rubber composites offer compelling advantages due to their flexibility and resilience. Due to reinforcing properties and high electrical conductivity, these materials can be transformed into viable electrode candidates by incorporating conductive additives like carbon nanotubes (CNTs). This study investigates the influence of dispersion and vulcanization methods on the mechanical and electrical properties of polyisoprene/CNT composites, aiming to optimize their suitability for flexible electrode applications. Two dispersion methods (conventional two-roll mill and latex dispersion) and two vulcanization systems (efficient and conventional) were employed. Comprehensive characterization encompassed electrical (resistivity, impedance spectroscopy), mechanical (tensile tests, rheometry), and interfacial properties (contact angle, zeta potential, linear voltammetry). Results demonstrate that the latex dispersion method significantly outperforms the two-roll mill approach. Latex-dispersed composites exhibited a tenfold increase in electrical conductivity and superior surface properties compared to conventionally dispersed counterparts, from 0.123 to 1.33 mS cm−1. Also, the efficient vulcanization system resulted in a modest decrease in modulus while maintaining tensile strength and significantly improving strain at break, from 1.83 to 6.82 MPa and 82.9 to 607%, respectively. This work provides valuable insights into optimizing dispersion and vulcanization techniques for developing high-performance conductive rubber composites with enhanced electrical and mechanical properties, which are crucial for advancing flexible electrode technologies.
Beyond static: Tracking the dynamic nature of water absorption and Young's modulus in IPMC devices Matheus Colovati Saccardo, Rafael Barbosa, Ariel G. Zuquello, Guilherme Eduardo de Oliveira Blanco, Kaique A. Tozzi, et al. Journal of Applied Polymer Science, 2024 Ionomeric polymer‐metal composites (IPMC) are advanced materials designed to mimic biological systems. Their performance depends on various factors, including electrical stimulus intensity, membrane hydration, ionic migration, and Young's modulus. However, there is a lack of studies in the literature investigating how the water absorption capacity and elastic modulus change over time in IPMCs. Understanding the hydration level variation as a function of time is essential because as this parameter deviates, the ionic migration capacity and Young's modulus also change, altering the device's electromechanical efficiency over time. To address this research gap, Nafion/Pt‐based IPMC devices exchanged with four monovalent cations (H+, Li+, Na+, and K+) and one ionic liquid (1‐butyl‐3‐methylimidazolium—BMIM+) were prepared, and a comprehensive investigation on how the water absorption capacity and Young's modulus vary as a function of time, relative humidity (RH), and counterion size was performed. The results revealed that the water uptake capacity is significantly higher and occurs more rapidly at higher RH levels and when the counterion's ionic radius decreases. Consequently, the time required for the device to reach osmotic equilibrium can range from 40 to 270 min, depending on the RH and counterion used. Furthermore, it was observed that the first natural frequency and Young's modulus also exhibit time‐dependent behavior. Under constant RH conditions, the mechanical properties of the IPMC can vary by up to 50% in less than 60 min. Notably, the combined results from water uptake capacity, Young's modulus, electrochemical impedance spectroscopy, and electromechanical response analyses (including blocking force, displacement, displacement rate, current, coulombic efficiency, and voltage) suggest that a morphological transformation within the polymer is likely to occur once RH exceeds 60%. This finding strengthens the hypothesis that ion migration is mainly influenced by their movement through Nafion's ionomeric channels rather than the filling of ionic agglomerates.
Review on the use of impedance spectroscopy for IPMC-like devices: application, models, and a new approach to data treatment Roger Gonçalves, Kaique Afonso Tozzi, Matheus Colovati Saccardo, Ariel Gustavo Zuquello, Rafael Barbosa, et al. Materials Advances, 2024 An extensive review of IPMC-like devices that use impedance spectroscopy as characterization. The proposed model considers the structure of the polymer and aims to be a unique model that can model a device in any humidity and counterion condition.
Novel IP2C sensors with flexible electrodes based on plasma-treated conductive elastomeric nanocomposites Rafael Barbosa, Roger Gonçalves, Guilherme Eduardo de Oliveira Blanco, Matheus Colovati Saccardo, Kaique Afonso Tozzi, et al. Smart Materials and Structures, 2024 Ionic polymer-metal composites (IPMC) are devices composed of metallic electrodes and an ionomeric polymer membrane in a ‘sandwich’ architecture and. Their main property is electromechanical actuation or sensing based on the movement of ions. Metallic electrodes are commonly used for their high electrical conductivity, malleability, and chemical resistance. However, the high cost of noble metals, such as platinum, long manufacturing time, and fatigue failure limit their application. Therefore, the replacement of metallic electrodes with conductive elastomeric nanocomposites (CENs) was evaluated to reduce the costs and complexity of manufacturing the device and increase its working life. In this work, carbon nanotubes were used as the conductive fillers. The dispersion to achieve high electrical conductivity was carried out directly in the synthetic or natural polyisoprene rubber latex assisted by surfactant and high-power sonication. To improve the adhesion between the elastomeric electrode and the ionic membrane (Nafion), plasma treatment with atmospheric air was applied as a surface modifier. This treatment improved the hydrophilicity and adhesion of the rubbers by forming oxygenated groups and increasing the surface nanoroughness. In this way, ionomeric polymer–polymer composite (IP2C) devices were fabricated using Nafion and plasma-modified CENs, this type of electrode is unprecedented in the literature for this application. These devices showed displacement and strain sensing capacity at levels close to the conventional IPMC in all tested frequency ranges and applied accelerations. Notably, the IP2C obtained better resolution at low frequencies than the control.
