Intelligent Color-changing Gels And Gel Actuators Based On Magnetic Nanoparticles

The main purpose of this work is to prepare the functional composite hydrogels composed of magnetic particles and stimulus response components,and to extend their functional application while improving their original performance.Firstly,The function of p H stimulation-response was obtained by rehydrolysis of color-changing gel prepared from neutral monomer;improved their mechanical properties by constructing double network method,and established the corresponding relationship between strain-resistance ratio change-color change of the gels.Secondly,the thermo-sensitive hydrogels with stable discoloration were obtained by introducing inorganic nano clay particles Laponite XLG into the system.At last,the magnetic hydrogels of polyamphoteric electrolyte were obtained by in situ method,we explored their shape memory behavior in acid-base solution and designed the actuators.The main contents of this work are as follows:1.p H stimulus-responsive color-changing gels were prepared by nonionic monomer-2-hydroxy ethyl methacrylate?HEMA?,acrylamide?AM?and carbon coated ferroferric oxide copolymer?Fe₃O₄@C?magnetic nanoparticles which can be ordered arrangement under the magnetic field.After copolymerization and hydrolysis,the gels can be different color response within the scope of the p H value of 2?7,and the process is reversible.In addition,the color-changing hydrogels with greatly improved mechanical properties were prepared by constructing double-network hydrogels,and their fracture strength was up to 875 k Pa.By introducing Na Cl solution into it,the relation of strain-resistance ratio change-color change was established.2.By introducing Laponite XLG into the system,we successfully stabilized charged Fe₃O₄@C magnetic nanoparticles in water and formed the temperature sensitive color-changing hydrogels by using N-isopropylamide?NIPAM?.The mechanical properties of the hydrogels were significantly improved,and its fracture strength is 3 times higher than that of the traditional color-changing organic gel of the same type,up to 100 k Pa,and it is not easy to be damaged when used.By comparing the effects of different formulations on the properties of color-changing gels,we discussed the role of Laponite XLG components in them.In addition,by combining this gels with polyacrylic acid?PAA?hydrogels as petal-like actuators,the actuating process of petal opening and closing can be realized in hydrochloric acid and water.3.The magnetic hydrogels of polyamphoteric electrolyte were prepared by in-situ method of sodium p-styrene sulfonate?Na SS?and 3-?isobutylamide?propyl trimethylammonium chloride?MPTC?,which improved the disadvantages of low magnetization and low mechanical strength of the traditional magnetic hydrogel.By observing the shape memory behavior of the magnetic hydrogels in acid and alkali solution,the possibility of the magnetic hydrogels as magnetic actuators was discussed.It is combined with PAA hydrogel to obtain the actuators that can grasp,move and loosen in acid and base solution.