| Gel is a kind of typical functional soft material,which is widely used in biology,medicine and so on,but it is easy to be destroyed by external force to affect its application.However,the gel with self-healing capacity can solve this problem.Dynamic covalent chemistry is one of the methods to prepare self-healing gels,such as imide bonds,acylhydrazone bonds,boronate ester bonds,disulfide bonds,etc.The features of dynamic covalent bonds are dynamic and reversible,which make the gels self-heal and responsive.In order to make the gel with better self-healing ability and multiple responsiveness,multiple dynamic covalent bonds have been introduced in the same system.In this work,we prepared organogel based on dynamic covalent chemistry,and the self-healing property and responsiveness of gel obtained were discussed.This paper consists of three parts:Part one:The research status and application of self-healing gel;Part two:Multi-responsive organogel based on multiple dynamic covalent bonds was prepared by 4-formyl phenylboronic acid,polyvinyl alcohol and 3,3’-dithiopropylhydrazine,and the formation of dynamic covalent bonds was characterized by Infrared spectroscopy and UV-Vis spectroscopy.The gel obtained showed good mechanical property,self-healing capacity and tri-responsiveness.The mechanical property of the gel can be controlled by changing the concentration of the monomers.The tensile test illustrates that the gel is stretchable,which can withstand large strain.Due to the boronate ester bond,acylhydrazone bond and disulfide bond in the system,the organogel can response to pH,glucose and redox.Acylhydrazone bond and boronate ester bond will break at a certain pH,boronate ester bond can dissociate in the presence of competitive molecule(glucose),and disulfide bond is sensitive to redox.A fast self-healing process was also observed by optical microscope.Part three:A fast self-healing organogel based on boronate ester bond and acylhydrazone bond was prepared by 4-formyl phenylboronic acid,polyvinyl alcohol and diacylhydrazine tartrate.The formation of dynamic covalent bonds were characterized by Infrared spectroscopy and UV-Vis spectroscopy.The self-healing process was observed by optical microscope,and it was found that the healing interface gradually disappeared,which illustrated that the organogel had the rapid self-healing capacity,and the tensile test proved that the gel had high self-healing efficiency.Due to the π-π stacking interaction,hydrogen bond and electrostatic interactions between gels and aromatic dyes,the organogel can adsorbed the dyes.According to the UV-vis absorption spectra,the organogel can adsorb methylene blue selectively. |
