Preparation And Properties Of Low-molecular-mass Gels And Self-healing Flexible Materials

The 3D network structure formed by non-covalent bonding gives Molecular Gels unique properties,such as stimulus responsiveness,phase transition controllability,etc.However,the weak intensity of the Molecular Gels greatly limits its application,while,both the chemical stability and stimuli responsive to dynamic covalent bond gel arises at the historic moment,this kind of gel does both conventional gel phase transition of reversible,they have self-healing damage and the excellent mechanical properties of chemical gels.It has formed a new type of soft material.Carbohydrates provide have been used successfully in the design of low molecular organic gelator(LMOG).However,the research is mainly limited to pyranoid carbohydrates provide,while other types carbohydrates provide(such as straight chain,furan sugars and pentaglucose,etc.)are still less concerned.In addition,self-healing materials based on Diels-Alder reaction have the characteristics of flexible preparation,mild repair conditions and multiple repairs,and have received extensive attention.However,how to produce high performance and multi-functional self-healing flexible materials simply and efficiently is still a problem.This thesis work focused on the construction of a new Molecular Gels system.The straight chain carbohydrate compounds were introduced into the LMOG system,and its morphology,mechanical properties and aggregation mechanism were systematically studied.In addition,flexible materials with self-healing properties was obtained by connecting graphene oxide functionalized by furan and bismaleimide containing flexible alkyl chain through Diels-Alder reaction,and their mechanical properties,self-healing behavior were studied in detail.The thesis mainly includes the two following sections:In the first section,three glucose derivatives containing benzene rings were designed and prepared by using(o-,m-,p-)phenylenediamine as linkers to connect gluconic acid with cholesterol.Their gelation abilities were evaluated in 30 commonly used solvents.It can be seen that the gelation abilities of the compounds are dependent strongly on the spacer structures of them,compound C2G with a critical gelation concentration(CGC)of 0.06%(w/v)in DMSO.The spacer structure,the concentration of the gelator and the nature of the solvent play a crucial role in the morphologies and rheological properties of their xerogels.It is worth mentioning that C2G/DMSO gel possesses smart and reversible thixotropic property.As revealed by FT-IR and 1H NMR,hydrogen-bonding and ?-? stacking are important in the formation of the gels.XRD study revealed that C2G assembled into a layered structure in its DMSO gel.In the second section,three kinds of flexible films(M1,M2 and M3)were prepared by Diels-Alder reaction with graphene oxide functionalized by furan as diene and bismaleimide containing flexible alkyl chain as dienophile.Tensile tests showed that with the incorporation of a little GO,the tensile elongation at break of the film by more than 764%,and the tensile strength of film up to 15.6 MPa.Additionally,the films showed excellent self-healing properties,completely self-healing in 4 hours at room temperature(25?)without any stimulation,meet the requirements of green protects,which is promising for applications in flexible sensors,artificial muscle and soft robot.