Composites of Polymer and Carbon Nanostructures for Self‐Healing Chemical Sensors

Abstract

1 of 8) 1600187 wileyonlinelibrary.combased on a thin film of molecularly modified nanoparticles deposited on top of a self-healing synthetic polyurethane layer that is patterned with self-healing electrodes. The sensor exhibited sensitivity to pressure and strain that is highly comparable to other technologies. Moreover, the same self-healing platform was sensitive to both polar and nonpolar VOCs, with a detection limit of 20 ppb. This self-healing device was adapted after small changes in its architecture to high resolution temperature sensor. The main challenge with this sensor was that the healing process could not be controlled by the intrinsic features of the sensing layer (molecularly modified nanoparticles), but rather it was induced by the process of intrinsic self-healing of the polyurethane substrate beneath it. In many instances, this induced healing ability causes several problems, such as low mechanical properties and loss of electrical conductivity of the healed film, which are harmful to the sensor.We now report on the development of a truly self-healing active sensing layer, i.e., a sensing layer that can heal itself intrinsically. To obtain both self-healing ability and electronic properties, active composites of self-healing polymers and 0D, 1D, and 2D carbon nanomaterials (and, for the sake of comparison, ionic nanomaterials) are used as a background of this investigation. The self-healing features of the composite-based sensing layers are examined and a proof-of-concept of their application for long-term monitoring or updating of human health through VOCs sensing is discussed. [20][21][22] Result and DiscussionThree different self-healing polymers (poly(propylene-urethaneureaphenyl-disulfide) PPUU-2S, poly(urethane-carboxyphenyl-disulfide) PUC-2S, and poly(2-hydroxypropyl methacrylate)/poly(ethyleneimine) PPMA/PEI) and 4 conductive materials (carbon black -CB, carbon nanotube -CNT, graphite, and lithium perchlorate -LiClO 4 ) (Figure 1a) were used for preparation of self-healing composites. The polymers have both flexible and self-healing features. The use of carbon structures are prefered because they are inexpensive, affordable, and their synthesis is well-established. We have then taken Despite recent dramatic development of materials with self-healing ability, fabrication of a self-healing devices remains challenging. In this paper, truly self-healing composites consisting polymers and carbon nanostructures are reported. Using a modified fabrication technique -called "layer-by-layer stamping" -chemical sensors are produced and characterized by infrared spectroscopy and various microscopy techniques. As a demonstration of the ability of the developed sensors to coexist with harsh operation conditions, the performance of the sensors under exposure to volatile organic compounds that are derived from human breath/skin is evaluated under different conditions of cutting and self-healing cycles. The results show a discrimination ability of the selected sensors to return to an operation level of...

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