The Study On Two-component Supramolecular Hydrogel Based On Small Molecules And Melamine

Supramolecular gels have great potential in many fields,such as drug delivery,tissue engineering,ion detection and sensors.Among them,the two-component supramolecular gel shows a big competitive advantage in stimulating responsiveness,which has attracted more and more attention.However,when stimulated by external environment factors,the existing two-component supramolecular gels can produce the one response and do not respond to multiple stimuli at the same time,which limit their application.So it is an important research hotspot to develop the two-component supramolecular gel with multiple stimuli responsive properties.Based on this,two kinds of two-component supramolecular hydrogels were constructed in water by using iminodiacetic acid?I?or nitrilotriacetic acid?N?and melamine?M?as two components respectively.The structure and basic properties of two kinds of hydrogels were studied by means of SEM,FTIR,rheometer and XRD.The gelling properties of small molecules in mixed solvents were also analyzed by using Hansen solubility parameters,and the prediction rules of the small molecular gel by solvent parameter were also given.Finally,the multiple-stimuli responses of two kinds of two component hydrogels to external environmental factors such as temperature,pH and ion were explored.The main contents are as follows:?1?M and I with a molar ratio of 2:1 or 3:1 could self-assemble to form a stable white opaque two-component supramolecular hydrogel in water.The results showed that based on intermolecular hydrogen bonding,M and I firstly formed supramolecular polymer structures through self-assembly in water,the structures further self-assembled to immobilize a large amount of water molecules,then the two-component supramolecular hydrogel system could be formed.The rheological test results displayed that the hydrogel had good mechanical properties and the storage modulus?G'?was always higher than the loss modulus?G''?,which showed the characteristics of typical gel.?2?N and M with the molar ratio of 1:1 could form stable two-component supramolecular gels in water or mixed organic solvents.The results showed that M and N firstly form supramolecular polymer structures based on intermolecular hydrogen bonds in solvents,and the structures further self-assembled by lamellar stacking and immobilized a large amount of solvent molecules,then the two-component supramolecular gel system was constructed.The Hansen solubility parameter method was used to analyze the gelling properties of MN in mixed solvents.It was found that the gel behavior of the system could be distinguished well by the hydrogen bonding force parameter??h?.When the value of?h was with the range of34.5⁴2.3,a stable gel system could be formed,which could be use to judge the gel behavior of two small molecules in some unknown mixed solvents.?3?The two kinds of two-component supramolecular gel constructed in this paper had multiple-stimuli response,which could respond to the stimulation of temperature,pH and fluoride ions.In addition,the two-component hydrogel of M and N could selectively identify Fe³⁺,Co²⁺and Ni²⁺.Those characteristics were expected to be applied in sensors and the selective recognition of halogen ions and metal ions.