Preparation And Properties Of Multiresponsive Hydrogels

Hydrogel is a kind of three-dimensional polymer network structure material with good mechanical properties and biocompatibility.Due to its excellent properties,hydrogels have attracted extensive attention in the fields of drug transport,artificial organs,flexible materials and tissue engineering.Among them,responsive hydrogels,as a series of hydrogels that can sense external environmental stimuli and make corresponding property and structure changes,have attracted extensive attention of researchers.However,the single responsiveness of traditional responsive hydrogels seriously hinders its expansion in practical applications.In order to solve this problem,it has become an important research proposition to design and prepare multiple responsive hydrogels by enriching the types of responsive hydrogels.Direct introduction of responsive functional monomers into hydrogel networks is one of the simplest and most effective strategies to give hydrogel response.In this paper,multiresponsive hydrogels with photothermal and ionic stimuli were prepared by freeze-thaw cycles and free radical polymerization.Adding chromophores into the gel network can give it a responsive color change performance.The polyvinyl alcohol/sodium alginate/malachite green hydrogels prepared by freeze-thaw cycle showed sensitive photochromic behavior under UV light.In the solution of different metal salt ions(Ca Cl2,Mg Cl2,Ba Cl2),the responsive discoloration property of different metal cation was demonstrated.The structure and properties of hydrogel samples before and after the response behavior were characterized by uniaxial stretching,IR spectroscopy and UV-vis spectroscopy.Through the test,it was found that after the hydrogel was irradiated by ultraviolet light and soaked in metal ion solution,malachite green molecules were dissociated into triphenylmethyl cation and hydroxide,which made the material show discoloration behavior.In addition,the mask test results show that the novel photoresponsive and ion-responsive hydrogels have great potential applications in the recording and storage of encrypted information.The introduction of responsive polymer fragments into the polymer chain can form a good energy dissipation mechanism and give the hydrogel excellent response performance.Chitosan quaternary ammonium salt/poly(acrylic acid-SBMA-3-acrylamide phenylboric acid)hydrogel prepared by free radical polymerization showed good mechanical properties and glucose response.The hydrogels showed different responses to the stimulation of glucose solution and salt solution.The structure and properties of hydrogels were investigated by various characterization methods.These good response behaviors indicate that chitosan quaternary ammonium salt/polyacrylate-SBMA-3-acrylamide-phenylboric acid hydrogels have good multiple response behaviors.