Preparation And Properties Of Smart Supramolecular Hydrogels Based On Dynamic Covalent Bonds

Supramolecular gel is a kind of soft materials which is self-assembled by small molecules containing different assembly elements through non-covalent interaction.With structural adjustability,stimulus responsiveness and self-healing recyclable properties,it has a wide range of applications in wound healing,drug delivery,molecular motors,photoelectric energy materials and other fields.However,it has a low mechanical strength,and the extensive application range is limited.Dynamic covalent bond as a chemical bond,which offers stability and reversibility,and is an effective method to enhance the mechanical strength of supramolecular gel.By introducing dynamic covalent bonds into supramolecular gels,we can obtain physical-chemical cross-linked multi-response supramolecular gels,which can effectively improve their mechanical strength.However,the research on supramolecular hydrogels is still remains in primary stage.At present,the research on supramolecular hydrogels is mainly focused on sugars,amino acids and nucleotides,and their applications are mainly concentrated in the medical field,while there are few researches on supramolecular hydrogels based on other supramolecular compounds and applications.In this thesis,the acylhydrazone bond and boro-oxicyclic bond were introduced into the supramolecular hydrogels.The hydrogels with excellent pH,temperature,conductivity and other multiple stimulus response and self-healing performance were obtained.At the same time,these two kinds of hydrogels are applied to biosensors and superhydrophobic coatings respectively.This thesis mainly includes the following two works:First part,1-(10-(4-formylphenoxy)decyl)pyridonium(FDP)was prepared,and mixed with diacylhydrazine adipate(ADH)as a gelling agent.It is first found that hydrogels(FDP-ADH hydrogels)can be formed in the whole pH range by adjusting solid content.The morphology of FDP-ADH dry gel was observed by SEM.The formation mechanism of hydrogels under different pH conditions was studied by 1HNMR and FTIR.The results showed that the acylhydrazone bond structure of hydrogels formed was different when under acidic and alkaline environment.The acid structure was ketone structure,while the alkaline structure was enol structure.At the same time,studies show that the hydrogel with a solid content of 10.0%and pH=1 has good temperature sensitivity,self-repair and electrical conductivity.The gel also has sensing properties of stress-strain and temperature,which can be used in flexible sensors and wearable devices.Second part,Iminoborate bond compound(MP)was designed and prepared.7 kinds of MP hydrogels were obtained by heating MP in water with different pH values.The morphology of MP hydrogel was determined by SEM.The structure of hydrogel was determined by FTIR and 1HNMR,and the formation mechanism of MP hydrogel was studied.The results show that MP hydrogels contain borooxygen hexacyclic structure.With the increase of acidity or alkalinity,the crosslinking degree of MP hydrogels increases.WAC tests of MP compound and MP xerogel show that they are hydrophobic,so they can be introduced into hydrophobic coatings.PDMS-SiO2 coating and PDMS-SiO2-MP coating were prepared by spraying method.The two coatings were systematically tested respectively,and the results showed that the introduction of MP not only enhanced the hydrophobicity,adhesion,friction resistance and corrosion resistance of the coatings,but also endowing the coatings with self-healing properties.Moreover,PDMS-SiO2-MP coating is universal in the choice of substrate.PDMS-SiO2-MP filter paper coating has good oil-water separation ability,and its oil-water separation efficiency remains above 90%after 10 oil-water separation cycles.