Thermoplastic polyurethane (TPU) reinforced with natural or renewable fillers gained significant attention in the scientific community and industries. The properties of TPU can be tailored using different reinforcements or blends to enhance its performance and elevate the potential applications of the composite. Besides, composites offer eco-friendliness, recyclability, and biocompatibility thus overcoming the environmental concerns. However, the manufacturing in mass quantity and upholding the quality of these composites has remained one of the principal challenges. Herein, we critically highlighted an overview of the current comprehension of the various eco-friendly and renewable fillers/fibers reinforced in TPU composites for tuning the mechanical and thermal properties of TPU. Some of the important research articles that discuss the influence of interactions, morphology, and modification/treatment of fillers are contained within to understand the behavior and consequence of reinforcements on the physical properties of TPU composites.

In this study, a highly flexible and wearable nitrogen dioxide (NO ₂ ) gas sensor was fabricated based on electrospun poly(vinylidene fluoride) (PVDF)/polyaniline (PANi)/graphitic-carbon nitride (g-C ₃ N ₄ ) blend nanocomposite (EBNC). g-C ₃ N ₄ /PANi nanocomposite (GPC) was synthesized by in situ polymerization technique prior to its incorporation into PVDF nanofibers, which ensured uniformity of dispersion. For the comparison study, PVDF/GPC nanocomposite film was fabricated using doctor blade technique. EBNC sensor exhibited high sensitivity, selectivity, reproducibility along with quick response and complete recovery. Electrospinning and GPC synergistically improved the performance of the EBNC based gas sensor. The superior gas sensing ability along with its low cost and the use of scalable electrospinning technique could make this system a promising one for the detection of gaseous NO ₂ .

In a unique approach to develop a “green” solution for in-situ monitoring, low-cost inkjet-printed temperature sensors on paper substrate were fully integrated into natural fiber-reinforced lightweight components for which structural health monitoring is becoming increasingly important. The results showed that the sensors remained functional after the vacuum infusion process; furthermore, the integration of the sensors improved the mechanical integrity and stability of the lightweight parts, as demonstrated by tensile testing. To verify the qualification of the printed sensors for the target application, the samples were exposed to varying temperature and humidity conditions inside of a climate chamber. The sensors showed linear temperature dependence in the temperature range of interest (−20 to 60 °C) with a TCR ranging from 1.576 × 10⁻³ K⁻¹ to 1.713 × 10⁻³ K⁻¹. Furthermore, the results from the tests in humid environments indicated that the used paper-based sensors could be made almost insensitive to changes in ambient humidity by embedding them into fiber-reinforced lightweight materials. This study demonstrates the feasibility of fully integrating paper-based printed sensors into lightweight components, which paves the way towards integration of other highly relevant sensing devices, such as strain and humidity sensors, for structural health monitoring of smart, sustainable, and environmentally compatible lightweight composite materials.

Herein, surfactant-assisted PANI nanorods were synthesized via the solid-state synthesis method at different concentrations of sodium lauryl sulfate (SLS). Upon the addition of SLS, the average rod diameter of PANI decreased from 72 ± 6 nm to 58 ± 6 nm. The electrical conductivity of PANI increased three-fold upon the addition of SLS (8.2 S cm⁻¹). Furthermore, the presence of SLS modulated the PANI chains, which facilitated the enhancement of the thermal stability. A PANI/SLS-based humidity sensor was built on a paper substrate through the doctor blade coating technique and its performance metrics were accessed under different humidity conditions. The PANI/SLS coated paper-based humidity sensor exhibited excellent response along with fast response/recovery characteristics. SLS assisted PANI nanorods having an improved electrical conductivity and high surface area readily interacted with water molecules, which significantly increased the sensitivity of the sensor up to 31.5 kΩ/%RH (linearity = 0.99). Furthermore, the sensor showed excellent response under physiological conditions such as respiration monitoring and skin moisture detection. The ultrasensitive humidity sensing performance of PANI/SLS coated paper with good skin-friendly characteristics makes it a potential material for multipurpose smart wearable devices.