Study On The Multiscale Structure-function Design And Properties Of Lignocellulose/Silk Fibroin Ionogel

Ionogels are widely used in the field of flexible electronics as a new soft functional material that is soft and ionically conductive.However,the weak mechanical properties of most ionogels limit their applications and lifetime to some extent.In recent years,many natural biopolymers have been extracted and have shown great competitiveness in the challenge of energy crisis,providing new opportunities for the development of gel materials and flexible electronics and other fields.Therefore,it is challenging to develop green bio-ionogels with good electrical conductivity and at the same time mechanical robustness.Based on the above problems,this thesis proposes a multi-scale structure construction and performance design strategy for biomacromolecule-based gel materials at the molecular scale,using green biomass resources cellulose and natural silk fibroin as research objects,and develops green biomass-based ionogels with adjustable structural properties,which have both outstanding mechanical properties and ionic conductivity,and apply them to flexible electronic devices,which can demonstrate high stimulation sensitivity,responsiveness and performance stability.The main research contents of the paper are as follows:(1)Purified cellulose with a polymerization degree of 658 was obtained by sodium chlorite method using poplar wood powder as raw material.The[Bmim]Cl ionic liquid was prepared using 1-methylimidazole and 1-chlorobutane as raw materials,and the resulting ionic liquid was verified to be of high purity.The optimal temperatures for the molecularization of cellulose and silk fibroin were determined to be 80℃ and 90℃,respectively.The characterization before and after the molecularization proved that the[Bmim]Cl ionic liquid was the non-derivatized cosolvent of cellulose and silk fibroin.The phase morphology change models of molecular systems with different proportions were constructed by rheological analysis.(2)Cellulose/silk fibroin molecular gel material was constructed by water molecular self-assembly strategy.The introduction of silk fibroin promoted the morphology,light transmittance and thermal stability of the gel material,and significantly improved the mechanical properties of the molecular gel.The tensile strength was 1.60 MPa,the elastic modulus was 2.63 MPa,and the toughness was 470 k J/m~3.Compared with single cellulose gel,the constructed flexible and transparent electronic skin can show high sensitivity to touch,bending and other external signals,and has deformable shape,high self-healing efficiency(96.9%)and excellent electrochemical performance(ionic conductivity 27.89 m S/cm).(3)In this chapter,a multiscale structure gel design strategy is proposed,and a gel material with microfibers,nanofibers and supramolecular hydrogen bond network is constructed,and the degree of gel molecularization can be regulated by heat treatment time,so as to regulate its mechanical properties.The gel with a molecular degree of about 48.6%showed a high tensile strength of 2.69 MPa,an elastic modulus of 7.3 MPa and a toughness of850 k J/m~3.(4)Based on the inspiration of the unique double parallel diagonal skeleton of glass sponge,the mechanical structure of silk fiber in the multiscale gel was further optimized,and the mechanical and electrical properties of the gel were significantly enhanced.The tensile strength was 6.5 MPa,the elastic modulus was 31.5 MPa,the toughness was 1540 k J/m~3,and the instantaneous impact resistance was 3.07 k J/m.At the same time,it also maintains an ionic conductivity of 49.6 m S/cm,which can sensitively sense various stimulus signals,demonstrating the application potential of the material in advanced fields such as impact protection soft materials and intelligent sensing equipment.