The Fabrication,Characterization And Applications Of Metal Ion Coordinated Hydrogel And Foam Template Aerogel

As an important kind of soft material,gel material can be seen everywhere in lives and life,such as skin,jelly,grease,etc.Hydrogels and aerogels are currently important research fields for gel materials,and exhibit important application value in the fields of biomimetic materials,biomedicine,aerospace and other fields.Therefore,the research on gel materials in this thesis mainly involves two aspects:one part is to study the construction and mechanism of high-strength fast-response hydrogels,thereby improving the shortcomings of the poor mechanical strength and slow response speed of the current hydrogels;the other part is to use protein foam as a template,aiming to make full use of biological macromolecules to build an environmentally friendly aerogel material.Through the traditional research and characterization methods of colloid and interface science,combined with the knowledge and methods of polymer synthesis and properties,the preparation mechanism of gel materials is revealed.The results can help promote the designability and analyzability of gel materials.The thesis consists of the following parts:In the Chapter ?,the basic concepts,types and applications of materials and fields related to gels and foams are introduced.Among them,high-strength hydrogels,thermosensitive hydrogels,and bio-based aerogels are discussed in detail.Starting from the current research frontiers,the basis for selecting the topic and research purpose of this thesis are drawn.In the Chapter ?,a double crosslinked hydrogel with adjustable strength and thermosensitivity was constructed.Hydrogels consisting of chemically crosslinked copolymers of 1-vinylimidazole and N-isopropylacrylamide are coordinated with four first transition metal ions,using the reversible coordination between metal ions and imidazole.The coordination enhances the mechanical properties of the hydrogel and adjusts the lower critical solution temperature of the hydrogel.The effects of the crosslinking degrees and the types of coordination metal ions on the mechanical properties and the lower critical solution temperature of the gel were discussed.The differences in the hydrogels after the coordination of the four metal ions were compared.The mechanical properties of the Zn2+ coordinated hydrogel are significantly improved compared to other hydrogels.The hydrogels have electrical conductivity,adjustable mechanical properties,and thermosensitivity,which can be used as the dual thermosensitive switch for a fire alarm.In the Chapter ?,a foam template method was used to construct bio-based hierarchically aerogels.The preparation of porous materials usually uses the template method,and the currently commonly used template method is mostly the emulsion template method.Because the drying process is the key step in the preparation of aerogels,foams can be used as templates to prepare aerogels.The porous structure of the foam can be used to simplify the drying process of aerogels.Thus,natural bio-macromolecules are used as raw materials.Among them,egg white protein is used as a foaming agent and gelator,and it plays a role of foaming and curing Carboxymethyl chitosan is used as a reinforcing phase,and dialdehyde starch is used as a crosslinking agent.The amino groups on the protein and carboxymethyl chitosan are crosslinked by Schiff-base reaction.The hydrogel is prepared by using foam as a template,and then the aerogel is obtained by freeze-drying.The aerogel is hydrophobilized by surface modification.It is used as an oil-water separating adsorbent.This method overcomes the limitation caused by the thermodynamic instability of the foam itself,and avoids the complexity and danger of common foaming agents or the use of reduced-pressure foaming;the obtained aerogel material has a novel structure and is environmentally friendly.