| In the era of declining non-renewable fossil energy,green and renewable resources are receiving more and more attention.As one of the most abundant biological resources,cellulose has many advantages such as regeneration,biodegradability and good biocompatibility.The establishment of hydrogen bond network between cellulose molecular chains enables it to have rigid crystallization zone and amorphous amorphous zone.The overlapping of these zones gives cellulose materials high mechanical strength but still good flexibility,which enables it to be used in the construction of various functional materials.However,the presence of crystal regions restricts configurational design and supramolecular self-assembly at the molecular level to construct novel cellulosic functional materials,because cellulose is difficult to dissolve in conventional solvents without degradation.The appearance of green solvents such as ionic liquid and alkali/urea enables us to break the constraints of hydrogen bond networks,realize the structural design and optimization of cellulose at the molecular level,and assemble various supramolecular cellulose materials.Self-assembly and structural design at the molecular level enable the material to have novel and unique properties beyond its own,making the prepared material with unique hydrogen bond network and microstructural designability and resulting in a series of significant properties such as strong physical absorbability and convertible properties.However,the design of cellulose materials is still at the nanoscale mixing and hybridization,and molecular size structure design and spatial configuration strategy are rarely involved to construct cellulose based functional materials.In this paper,we successfully constructed an ion-gel material(called Cel-IL dynamic gel)with switchable structure and performance based on the design and self-assembly of cellulose molecular hydrogen bond network.The Cel-IL dynamic gel has such adjustable properties as mechanical strength,ionic conductivity,viscoelasticity and self-healing.Under the condition of limited water content,Cel-IL dynamic gel presents a thornlike Turing microstructure,which can realize self-healing in a short time with strong adhesion and high ionic conductivity.When the water content increased to 32wt%,the microstructure of the gel changed into a dense and compact Turing network,showing good ductility and strength.The ionic conductivity significantly increased to over 40 m S cm-1,which was significantly higher than that of other ionic gel materials.Based on Cel-IL dynamic gel material,we developed a flexible,transparent,design and biocompatible electronic skin device with high sensitivity,which can sense a variety of human mechanical stimuli(such as sound,cough,respiration,etc.)and humidity transformation,showing a good potential for application in human health detection.At the same time,we successfully built a mechanical properties can be self-regulation called Cel-PAAm materials follow the molecular conformation restructuring strategy.Due to the switch of the aggregated state structure of sex,the Cel-PAAm materials can switch at any time between the hard and soft gel materials,and improved modes of Cel-PAAm material has higher mechanical properties(470 times than soft gel for the modulus of elasticity),its puncture resistance and impact strength is superior to the metal aluminum.Under the strategy of molecular configuration recombination,Cel-PAAm materials of various complex shapes can be designed and prepared,and the prepared stabbing armor and extreme speed sliding mold show great application potential.This research based on the homogeneous system of cellulose molecules,cellulose based functional materials with switchable and self-regulated properties can be prepared through molecular hydrogen bond network design and self-assembly regulation,and it provides a good guiding significance and reference for the design of other new functional materials. |
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