Preparation and properties of flexible conductive polydimethylsiloxane composites containing hybrid fillers

A Flexible Carbon Nanotubes-Based Auxetic Sponge Electrode for Strain Sensors

Soft compliant strain gauges are key devices for wearable applications such as body health sensor systems, exoskeletons, or robotics. Other than traditional piezoresistive materials, such as metals and doped semiconductors placed on strain-sensitive microsystems, a class of soft porous materials with exotic mechanical properties, called auxetics, can be employed in strain gauges in order to boost their performance and add functionalities. For strain electronic read-outs, their polymeric structure needs to be made conductive. Herein, we present the fabrication process of an auxetic electrode based on a polymeric nanocomposite. A multiwalled carbon nanotube/polydimethylsiloxane (MWCNT/PDMS) is fabricated on an open-cell polyurethane (PU) auxetic foam and its effective usability as an electrode for strain-gauge sensors is assessed.

Properties of Graphene-Thermoplastic Polyurethane Flexible Conductive Film

Flexible conductive films were prepared via a convenient blending method with thermoplastic polyurethane (TPU) as matrix and nanocrystalline cellulose (NCC) modified chemically reduced graphene oxide (RGO/NCC) as the conductive fillers. The relationships between the electrical and thermal properties as well as the tensile strength and electrothermal response performance of the composite film and the mass content of reduced graphene oxide (RGO) and the initial TPU concentration were systematically investigated. The experimental results show that the resistivity of the composite film with the mass content of RGO/NCC of 7 wt% and an initial TPU concentration of 20 wt% is the minimum of 8.1 Ω·mm. However, the thermal conductivity of composite film with mass content of RGO/NCC of 5 wt% and the initial TPU concentration of 30 wt% reaches a maximum of 0.3464 W·m−1·K−1, which is an increase of 56% compared with pure TPU. The tensile strength of the composite films with mass contents of RGO of 3 wt% prepared with the initial TPU concentrations of 20 wt% reaches the maximum of 43.2 MPa, which increases by a factor of 1.5 (the tensile strength of the pure TPU is 28.9 MPa). The composite conductive film has a fast electrothermal response. Furthermore, superhydrophobic composite conductive films were prepared by immersing the composite conductive film into fluorinated decyl polyhedral oligomeric silsesquioxane (F-POSS) ethanol solution. The water contact angle of the superhydrophobic composite conductive film reaches 158.19° and the resistivity of the superhydrophobic composite film slightly increases and still has good conductivity.