The ongoing miniaturization of devices and development of wireless and implantable technologies demand electromagnetic interference (EMI)‐shielding materials with customizability. Additive manufacturing of conductive polymer hydrogels with favorable conductivity and biocompatibility can offer new opportunities for EMI‐shielding applications. However, simultaneously achieving high conductivity, design freedom, and shape fidelity in 3D printing of conductive polymer hydrogels is still very challenging. Here, an aqueous Ti3C2‐MXene‐functionalized poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate ink is developed for extrusion printing to create 3D objects with arbitrary geometries, and a freeze–thawing protocol is proposed to transform the printed objects directly into highly conductive and robust hydrogels with high shape fidelity on both the macro‐ and microscale. The as‐obtained hydrogel exhibits a high conductivity of 1525.8 S m–1 at water content up to 96.6 wt% and also satisfactory mechanical properties with flexibility, stretchability, and fatigue resistance. Furthermore, the use of the printed hydrogel for customizable EMI‐shielding applications is demonstrated. The proposed easy‐to‐manufacture approach, along with the highlighted superior properties, expands the potential of conductive polymer hydrogels in future customizable applications and represents a real breakthrough from the current state of the art.
Conductive nanocomposites are often piezoresistive, displaying significant changes in resistance on deformation, making them ideal for use as strain and pressure sensors.Such composites typically consist of ductile polymers filled with conductive nanomaterials, such as graphene nanosheets or carbon nanotubes, and can display sensitivities, or gauge factors, which are much higher than those of traditional metal strain gauges. However, their development has been hampered by the absence of physical models which could be used to fit data, or to optimise sensor performance. Here we develop a simple model which results in equations for nano-composite gauge factor as a function of both filler volume fraction and composite conductivity. These equations can be used to fit experimental data, outputting figures of merit, or predict experimental data once certain physical parameters are known. We have found these equations to match experimental data, both measured here and extracted from the literature, extremely well. Importantly, the model shows the response of composite strain sensors to be more complex than previously thought and shows factors other than the effect of strain on the interparticle resistance to be performance-limiting.
While polymers are typically processed using methods such as compression molding, injection molding, extrusion, and thermoforming, [10] polymer nanocomposites are typically prepared by solution blending, melt mixing/compounding, in situ polymerization, and composite self-assembly. [11] Nanocomposite formation by printing is somewhat less common. [12] Depending on the matrix, nanocomposite materials can be very soft and so skin mountable. [1] They also have high working strain ranges making them ideal candidates for emerging areas such as wearable sensing. [13,14] Although their elec-Research data are not shared.
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