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In this work, polyurethane sponge is employed as the structural substrate of the sensor. Graphene oxide (GO) and polypyrrole (PPy) are alternately coated on the sponge fiber skeleton by charge layer-by-layer assembly (LBL) to form a multilayer composite conductive layer to prepare the piezoresistive sensors. The 2D GO sheet is helpful for the formation of the GO layers, and separating the PPy layer. The prepared GO/PPy@PU (polyurethane) conductive sponges still had high compressibility. The unique fragmental microstructure and synergistic effect made the sensor reach a high sensitivity of 0.79 kPa−1. The sensor could detect as low as 75 Pa, exhibited response time less than 70 ms and reproducibility over 10,000 cycles, and could be used for different types of motion detection. This work opens up new opportunities for high-performance piezoresistive sensors and other electronic devices for GO/PPy composites.

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In this work, a piezoresistive sensor structure based on carbon black (CB)@polyurethane (PU) yarn material was developed. Specifically, CB@PU yarn was constructed by the polymer-mediated water-based electrostatic deposition method. The distribution of the yarn was artificially controlled to fabricate conductive networks. The CB conductive layer was efficiently supported by the net-like structure of PU yarn, thus generating collaborative advantage. The as-fabricated pressure sensor not only displayed compressibility of over 97%, but also detected a wide pressure change from 25 Pa to 20 kPa. Furthermore, this sensor exhibited response time of less than 70 ms and reproducibility of over 10,000 cycles. The advantages of the CB@PU network ensured this pressure-sensitive structure enormous potential application in pressure sensitive equipment.

Depending on the fact that most pillared clays show poor thermal stability, the study on the synthesis of novel Si-pillared montmorillonites (Si-MMT) with high themal stability have been carried out. Furthermore, Powder X-ray Diffraction (XRD), Fourier Transformation Infra-red Spectra (FTIR), Nitrogen Adsorption-Desorption Isotherms were applied in order to study the thermal stability and mechanisms of the pillared materials. A mechanism corresponding to Si-MMT with a good thermal stability was thus established: after calcination, protons are liberated by dehydration or dehydroxylation. These protons disrupt the silicon-oxygen-aluminium bridges where there are Al substitutions in the tetrahedral sheet of the montmorillonite. Some of silicon and aluminum tetrahedra invert to react with the pillaring agents and yield covalent bonds which firmly fix the pillars to the host clay. The Si-MMT are thermally stable up to 800 ℃ and possess large basal spacings of about 2.5 nm after thermal treatment at 800℃.