Self-assembly Preparation And Properties Research Of Multiple Stimulus-responsive Supramolecular Hydrogel

In recent years,intelligent-responsive hydrogels have attracted extensive attention from researchers,especially stimuli-responsive hydrogels and self-healing hydrogels.Intelligent responsive hydrogels can easily respond to small stimuli from the external environment,the interactions within or between molecules of the hydrogel can be changed under these stimuli,which may lead to the changes in the gel structure and even properties.The above properties make hydrogels have great potential in some fields,such as wound dressings,injectable drug delivery,biosensors,tissue engineering scaffolds,and targeted and controlled release of targeted drugs.The intermolecular interactions that induce the phase transition of hydrogels are mainly hydrogen bonds,van der Waals forces,ionic strength and hydrophobic interactions.By designing the structure and properties of hydrogel molecules,hydrogels can be endowed with some properties such as easy assembly,tunability,stimulus response,and self-healing.Because the hydrogel material is similar to living tissue,it exhibits good biocompatibility and biodegradability in the human body.At the same time,because the hydrogel has three-dimensional network structure,which can lock a large amount of water and swell without breaking its mechanism and dissolving.In this paper,through molecular design,a self-assembly hydrogel with stimuli-responsive was prepared,and its properties were further investigated.The research results are as follows:1.A two-component supramolecular self-assembly hydrogels TPS was prepared with riboflavin sodium phosphate(RP)and 2,6-diaminopurine(DAP).Complementary sites exist between RP and DAP,enabling gelation through hydrogen bonding.In this study,theoretical chemical calculation is combined.The possible connection situation is designed through the geometric structure and properties of RP and DAP,and the structures are optimized with Gaussian software to calculate the hydrogen bonding energies of RP and DAP under different molar ratios.The computational results were used to guide experiments to improve the reliability of experiments and understand their chemical mechanisms.The two-component hydrogels were characterized by scanning electron microscopy(SEM),infrared spectroscopy(FTIR),ultraviolet-visible absorption spectroscopy(UV-Vis),fluorescence spectroscopy(FL)and X-ray diffraction(XRD),and the structure and properties of hydrogels were analyzed and discussed.In addition,the prepared TPS two-component supramolecular hydrogel exhibits dual temperature and p H responsiveness,thermal reversibility,thixotropy,and good photoluminescence properties.2.OACS-DAP supramolecular hydrogels were successfully prepared with orotic acid(OA)modified chitosan(CS)and 2,6-aminopurine(DAP).In this study,orotic acid modified chitosan(OACS)were prepared with an amide reaction via the carboxyl group on OA and the amino group on CS,and then utilized the CO-NH-CO group on the pyrimidine backbone of OA to form a stable hydrogen bond structure with DAP.They then self-assemble to form hydrogels at room temperature.The supramolecular hydrogels were characterized by scanning electron microscopy(SEM),infrared spectroscopy(FTIR),proton nuclear magnetic resonance(~1H NMR)and X-ray diffraction(XRD),and the structure and properties of hydrogels were analyzed and discussed.In addition,the prepared OACS-DAP supramolecular hydrogel exhibits dual temperature and p H responsiveness,thermal reversibility,thixotropy,self-healing,injectability,and electrical conductivity.The TPS two-component supramolecular hydrogels and OACS-DAP supramolecular hydrogels prepared in this paper are both intelligent and responsive hydrogels with excellent properties.It provides research ideas for the application of supramolecular hydrogels in cell imaging,wound healing,drug injection,3D printing and sensors.