Production and characterization of flexible silicone rubber electrodes with carbonaceous conductive fillers for use in IPMC-based actuators

• Grant number: 24/12824-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2025
• End date: February 28, 2026
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Nonmetallic Materials
• Principal Investigator: Carlos Henrique Scuracchio
• Grantee: Pedro Zago Formis
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

iEAPs (Ionic Electroactive Polymers) have been studied over the last few decades as a new matrix for electromechanical actuators in medicine and robotics. This is due to the ability of these materials to generate silent, light and precise movements with great displacement from small electrical stimuli (in the order of 1 to 5 V). In addition, they have low density, low cost, simple production, weather resistance, easy miniaturisation and low energy consumption. Ionic polymer-metal composites (IPMCs) consist of an iEAP membrane (180-200 µm) between extremely thin metal plates (5-10µm), usually made of noble metals such as platinum or silver, which act as electrodes. The most commonly used iEAPs for this type of application are those with a hydrophobic main chain (made up of PTFE, for example) and short branches with hydrophilic ionic groups, such as sulphonated ethers. Although more than one material falls into this category, the most widely used is Nafion.One of the difficulties encountered in scaling up the production of these IPMCs is the need for efficient electrodes made from abundant, low-cost raw materials. Currently, noble metal electrodes (platinum, gold or palladium) are used, but their availability and cost are prohibitive for large-scale production of IPMCs, as well as losing performance over time due to material fatigue. On the other hand, in recent decades various composites (especially nanocomposites) with a polymer matrix and conductive carbonaceous fillers (such as Conductive Carbon Black, cCB, Carbon Nanotubes, CTN, and graphene and its derivatives) have been studied. When the electrical percolation limit of these composites is exceeded, it is possible to achieve conductivities comparable to those of some metals, with the advantage of having a highly flexible, low-cost and highly durable material. This work therefore proposes the use of silicone composites with conductive carbonaceous fillers (carbon nanotubes, CTN, and conductive carbon black, cCB) to obtain a conductive material that is flexible enough to replace metals in IPMCs.