Functional Silk Fibroin/Cellulose Nanocrystalline Composite For Potential Sensing Material

Low sensitivity,high quality,and difficulty in carrying are shortcoming to wearable devices in early years.In order to solve these problems,researchers have focused on wearable devices with high sensitivity,light and portable.Furthermore,in order to meet the theme of today's era about environmental protection,biodegradable wearable devices are the development trend in this field.Compared to graphene and carbon nanotubes,which are highly sensitivity but costly and difficult to degrade,natural protein based SF has excellent biocompatibility and biodegradability.In this study,SF was used as matrix material,and cellulose nanocrystals(CNCs),which was obtained by hydrolyzing microcrystalline cellulose,was used as a reinforcing agent to prepare a composite material.The effects of the content of CNCs on the cross-sectional morphology,of hydrogen bond fraction,thermal stability,mechanical properties and sensing properties of the composite membrane.Furthermore,the application prospects of SF/CNCs composites as electronic skin in the sensing field were studied.(?)Preparation of silk fibroin/cellulose nanocrystalline composite membrane and multiple sensing performance studies.The SF/CNCs composite membrane was prepared by solution casting.SEM showed that CNCs was dispersed in SF matrix,which was beneficial to the formation of hydrogen bonds between CNCs and SF.Using the Gauss/Lorentz function to fit the infrared peaks of each membranes,it was calculated by formula that the maximum hydrogen bond fraction reached 0.71.Simultaneously,new hydrogen bonds further improved the thermal stability and mechanical properties of the composite membrane.Due to the addition of CNCs with a rigid molecular chain,the hierarchical structure of the composite membrane improved its barrier properties.More importantly,the high density hydrogen bonds endowed the membrane well responsiveness,the rate of voltage change about bending response and ethanol gas response of the composite membrane reached 45%and 150%,respectively.In addition,the composite membrane had a higher ethanol gas response[(?V/V0*100%)>200%]in bending status than in normal status due to weakening of the steric hindrance effect.(?)Preparation of silk fibroin/cellulose nanocrystalline composite conductive gel(SCP)and sensing properties studies.Polyacrylamide molecular chain was added by homogeneous radical polymerization and SCP was successfully prepared.The SCP's response to different temperature,gases and human activities was studied.After a variety of sensing tests,it was found that SCP had a good response to torsional forces,with a resistance change rate of up to 80%(twisted 180°).Besides,it had a obvious response to higher temperatures(above 50?).Compared with room temperature,SCP showed a 17.5%resistance change rate at 70?,indicating that SCP had development prospects in the field of temperature sensing.