Study On PVA/ChCl Deep Eutectic Blend System And Its Application In Flexible Sensor

Deep Eutectic Solvent(DES)is a new type of ionic liquid(IL)analog.Ion gel sensors composed of deep eutectic solvent have the advantages of low cost,good biocompatibility,and high ionic conductivity over a wide temperature range(from subzero to high)which has made a great contribution to the development of ion gel sensors.Polymerizable deep eutectic solvent(PDES)is a deep eutectic solvent formed by the combination of polymerizable hydrogen-bonded donor and hydrogen-bonded acceptor.By forming a deep eutectic solvent first and then polymerizing it,transparent and flexible elastomeric materials can be obtained.However,the application of PDES is greatly limited due to the complex and difficult to control polymerization process and the relatively high cost.To solve the above problems,this thesis proposes for the first time the preparation of polymer-based deep eutectic composites by one-step solution blending using commercial polyvinyl alcohol(PVA)as the hydrogen bond donor and choline chloride(ChCl)as the hydrogen bond acceptor.The method is simple to implement and suitable for large-scale production.On this basis,this work also presents an in-depth study on the application of PVA/ChCl deep eutectic composites as resistive sensors and friction nanogenerator type self-powered sensors.The main research contents are as follows.1.PVA/ChCl deep eutectic blends were prepared by solution blending method,and the compatibility,intermolecular interaction and crystallization behavior of the blends were investigated.The results showed that PVA and ChCl were compatible and formed eutectic,in addition,the addition of ChCl inhibited the crystallization of PVA so that it had excellent mechanical properties and tensile reversibility(elongation at break: 460 %;modulus: 70 MPa;fracture stress: 51.4 MPa).2.PVA/ChCl resistive sensors were prepared based on the PVA/ChCl deep eutectic system in 1.where the ionized ChCl provides excellent electrical conductivity to the eutectic and is able to convert the deformation of the eutectic into an electrical signal output.The sensor exhibited a wide strain detection range(5%-200%)and a fast response time(150 ms),which remained stable over 200 cycles of testing.In addition the sensor can also be used as a temperature and humidity sensor due to the response of choline cations and chloride ions to temperature and humidity.3.The PVA/ChCl friction nanogenerator was prepared using the PVA/ChCl deep eutectic system in 1 as the positive friction layer and PTFE etc.as the negative friction layer.The output performance of the friction nanogenerator under different ChCl loads was investigated and made into a self-powered sensor for human motion detection and self-powered handwriting recognition system.