Development Of Flexible Sensing Silver Nanowires Composite Double-Network Ionogels

With the development of electronic technology and flexible wearable devices,traditional rigid conductors can no longer meet the increasing demands of people.The ionogel materials have gradually entered people’s field of vision due to its advantages of flexibility,transparency,conductivity,and wide use conditions.Ionogel is a kind of gel material filled with ionic liquid in the gel networks.It has the flexibility of polymer and the advantages of high conductivity,high transmittance and non-evaporation of ionic liquids.It has been used in lithium batteries,super capacitors,flexible sensing and other fields.However,it is still challenging to prepare an ionogel with high mechanical strength,high transparency and high conductivity.In this paper,two ionic liquids[EMIM]DCA and[EMIM]BF4 were first synthesized by a two-step synthesis method,and they were characterized by FTIR spectroscopy and 1H-NMR spectroscopy,which confirmed the successful synthesis of these two substances.Using these two ionic liquids,the next step is to prepare the ionogel.Polymerizable electrolytes were used as monomers to explore the differences in the performance of ionogels with different charge networks.2-acrylamido-2-methylpropanesulfonic acid(AMPS),acrylic acid(AA),acrylamide(AM),methacryloxyethyltrimethylammonium chloride(MTC)were used as monomers to respectively Four double-network gel materials with different charges were prepared,and they were immersed in two ionic liquids[EMIM]DCA and[EMIM]BF4 to fully exchange water with ionic liquids.The tensile strength,tensile strain,electrical conductivity,and light transmittance of these 8 ionogels were compared.Among them,the PAMPS-based double network ionogel PAMPS-DN-1.2^[EMIM]DCA ionogel filled with[EMIM]DCA ionic liquid exhibits good performance,with a tensile stress of 0.27 MPa and tensile strain It reaches 153%and most of the light transmittance in the wavelength range of 400 nm-800 nm is higher than 80%,and the conductivity reaches 1.3 mS m-1.The silver nanowires were prepared by the polyol reduction method,and the silver nanowire grids with higher light transmittance were prepared by the ice template method.The silver nanowire grid was doped into PAMPS-DN-1.2^[EMIM]DCA to prepare the silver nanowire composite ionogel AgNWs@PAMPS-DN-1.2^[EMIM]DCA.The conductivity of AgNWs@PAMPS-DN-1.2^[EMIM]DCA is 3.5 mS m-1 higher than that of the ionogel without silver nanowires.Two ionogels AgNWs@PAMPS-DN-1.2^[EMIM]DCA and PAMPS-DN-1.2^[EMIM]DCA were used to prepare two ionogel-based flexible strain sensors.The sensor adopts a sandwich structure,using copper foil tape on both sides of the gel to draw out two wires to connect to a multimeter to collect resistance signals.Among them,AgNWs@PAMPS-DN-1.2^[EMIM]DC A sensor has GF=23.0,and the sensitivity is higher.The sensor can be used to detect the real-time motion state of the human body at the joints of the human body.It shows that the material shows great potential in the field of flexible sensing in the future.