| Flexible visually interactive strain sensing materials is a kind of materials which can transform mechanical strain into electrical and optical signal simultaneously.It is mainly composed of strain sensing materials and optical materials.However,usual visual interactive strain sensing materials based on color-changing dyes have the problems of narrow color changing range,slow response speed and small strain range,which limit limit their visual performance.In order to solve the above problems,using the advantages of adjustable mechanochromism and the fast response characteristics of photonic crystal hydrogels,this paper prepared electronic fibers with color change to tensile in the full visible spectrum,ionic-conductive photonic crystal hydrogels with rapid response to temperature,tensile and pressure,and ionic-conductive photonic crystal organohydrogel with anti-freezing,non-drying and antibacterial properties.They were applied to visually interactive strain sensing.Firstly,based on the coaxial structure design,the PDGI/PAM-EME electronic fibers with synchronous response of optical and electrical signals were prepared.Photonic crystal hydrogel microtubules were prepared by co-assembly of dodecylglyceryl itaconate（DGI）bilayer and polyacrylamide（PAM）;Ecoflex/MWCNTs/Ecoflex（EME）electronic fibers were then prepared by loading multiwall carbon nanotubes（MWCNTs）onto silicone rubber fibers（Ecoflex）.The two materials are coupled into multi-sheath PDGI/PAM-EME visually interactive sensing material.During stretching,the PAM polymer network can be highly deformed,which greatly reduced the lattice spacing of sensing materials,causing the structural color to gradually change from red（635 nm）to blue（440 nm）,and the tensile range was 0-200%.At the same time,the slip of MWCNTs increased the relative resistance of sensing materials from 0%to 3088%.The multi-sheath can ensure the synchronous response of optical and electrical signals of sensing materials to stretching,with a response time of 80ms under 20%stretching,which can visually monitor the movement of human joints and tiny vibrations of muscles.Secondly,the fast thermochromic C12DMAO/PDAAM-co-PAM ionic-conductive photonic crystal hydrogels were prepared,by using the adjustable electrostatic repulsion between the charged bilayer.Photonic crystal hydrogels were prepared by periodically fixing the positively charged N,N-dimethyl-1-dodecylamine N-oxide(C12DMAO)bilayers in the poly-（diacetone acrylamide-co-acrylamide）（PDAAM-co-PAM）hydrogel matrix.The electrolyte salt Na Cl was introduced into the matrix to make it conductive.Using it as an optical element,the visually interactive strain sensing materials with sandwich-like structure were constructed.When the temperature increased from 6°C to 36°C,the electrostatic repulsion inside the matrix caused the lattice spacing to expand,the structure color shifted from 470 nm to 680 nm,and the fastest response time was only～330 ms,the relative resistance decreased from 82%to-43%;During stretching（0%-100%）,synchronous structural color change（650 nm-455 nm）and relative resistance change（0%-140%）were generated;During compression（0 KPa-2.2 KPa）,synchronous structural color change（650nm-455 nm）and relative capacitance change（0%-19%）were generated,and the spatial distribution of stimulation was fed back through the change of structural color.Finally,in order to solve the problem of quality loss and easy growth of harmful bacteria in the photonic crystal hydrogels during the sensing process,the GML/PDAAM-co-PAM ionic-conductive photonic crystal organohydrogels were obtained through the solvent-exchange method and the introduction of antibacterial materials as visually interactive strain sensing materials.Photonic crystal hydrogels were self-assembled by of antibacterial surfactant monoglycerin laurate（GML）bilayers and PDAAM-co-PAM.Then,the water inside the matrix was replaced with non-volatile,low freezing point polyethylene glycol 200（PEG200）and antibacterial ionic liquid 1-Ethyl-3-methylimidazolium bis（trifluoromethylsulfonyl）imide（EMITFSI）to make it has the properties of non-drying resistance,freezing resistance and high temperature resistance.When this sensing material was stretched（0%-100%）,synchronous structural color change（650 nm-455 nm）and relative resistance change（0%-255%）were generated;During compression（0 KPa-8.05 KPa）,synchronous structural color change（650 nm-420 nm）and relative resistance change（0%-30%）were generated;When the temperature increased from-20°C to 80°C,the relative resistance decreased from 1819%to-85%,and the structural color changed slightly（642nm-667 nm）.In addition,the antibacterial ability of GML and EMITFSI made the bacteriostatic rate of the sensing material against S.aureus,B.subtilis and C.albicans greater than 99.9%. |
