Studies On Synthesis And Properties Of Stretchable Pillararene-containing Supramolecular Gel

Polymeric materials with stretchable property have got plenty of attention due to their widespread applications in the fields of life science,material science,information science.For gel materials,it is well known that there is usually a balance between modulus and elongation.Generally speaking,rigid structure often provides higher tensile strength,while flexible structure endows the material with greater elongation and rapid self-healing.The supramolecular gels have become the focus of research in recent years due to their good mechanical and quick self-healing properties.As the fifth generation of macrocyclic molecules,pillararenes have highly symmetrical rigid columnar structures and electron-rich cavities,which have attracted increasing attention.However,due to the steric hindrance of pillararene and its specificity to solvents,most of the work is focused on their functionalization,but the study of the mechanical properties of supramolecular gels is rarely reported.In this thesis,by introducing the flexible structure into the gel system,the mechanical properties of supramolecular materials were conveniently controlled by reasonably adjusting the ratio of pillararene to the flexible chain segment,and then the influence of host-guest complexation on the properties of supramolecular gel materials is studied.The main contents include:The pillar[5]arene functionalized acrylate AAP5 A and pyridinium functionalized acrylate G were designed and synthesized.The bifunctional cross-linker of host-guest supramolecule(HGS)was prepared by mixing AAP5 A with G in acetone by hostguest interaction.After that,flexible n-butyl acrylate(BA)was introduced as the comonomer,and a transparent cross-linked supramolecular polymeric material(SP)was obtained by free radical polymerization under UV light.With the increasing of HGS content,the mechanical properties of supramolecular polymeric materials increased significantly.The results showed that the gel exhibited maximum tensile strength of 3.4MPa with the highest content of HGS,indicating that the accumulation of pillararene can effectively improve the tensile strength of the gel.On the other hand,the strain at break of the gel can reach 3000 % when the content of butyl acrylate was lowest,indicating that the soft polymer with lower glass transition temperature can effectively maintain the toughness of the gel.In addition,the energy absorption efficiency ω of the supramolecular gel reached 93 %,which makes it possible to be used as energy absorption materials.Furthermore,it exhibited self-healing and stimulus responsive properties owing to the dynamic host-guest interaction.Random polymers poly(AAP5A-co-HDA)with different contents of pillararene were prepared.Then the guest molecules of pyridinium functionalized with hydrogen bond group G’ were designed and synthesized.After that,rod-coil supramolecular gels(SMG)were prepared in chloroform due to strong interaction of host-guest complexation and hydrogen bond.Such supramolecular gel exhibited tunable stretchable property by varying the content of rigid and flexible structures.By adjusting the molar ratio of rigid and flexible structures,the mechanical properties of the gel material can be changed.The results showed that the accumulation of pillararene can occur to a greater extent with the aid of hydrogen bonding.Through the reasonable distribution of rigid and flexible structures,such material exhibited excellent tensile properties,with the Young’s modulus of 1.78 MPa and the strain at break of 543 %,respectively.In addition,the gel can adsorb anionic dyes,and realize rapid self-healing and stimulus response.