The Preparation Of Graphite Oxide/starch (gelatin) Composite Hydrogel And Its Electric Field Response Performance

Intelligent hydrogels are a type of soft materials which can responds to external stimuli.Among them,the electric-responsive hydrogel which can applied electric field as stimuli external stimulus,and may change their physical and chemical properties under the action of an electric field,also it can convert electrical energy into mechanical energy.In this paper,we hope to prepare hydrogels with high electric field response.And mainly chooses the environmentally friendly natural polymer materials—starch and gelatin as raw materials,and uses glutaraldehyde as a cross-linker to prepare GO/natural polymer by adding different concentrations and oxidation degree of graphite oxide(GO)to the system.The effects of GO content,oxidation degree and applied electric field strength on the electrical response of the composite hydrogel were investigated.Among them,the composite hydrogel prepared under the action of an external electric field will be named A-hydrogel(E=0.5 kV/mm,0.8 kV/mm),and the composite hydrogel prepared under the non-electric field will be named B-Hydrogels.The dynamic elastic viscoelasticity spectrometer(DMA)was used to test the storage elastic modulus(GA,GB)of these two types of composite hydrogels,and the increment(△G,△G=GA-GB)and increment sensitivity(△G/GB)in storage modulus of the hydrogel was calculated to reflect its electric field response performance;Using the scanning electron microscopy(SEM)to observe the skeleton structure of the composite hydrogel;Infrared spectroscopy(FTIR)and thermogravimetric analysis(TGA)and other methods explore the internal gelation mechanism of composite hydrogels.The main study of the paper are as follows:1.Using glutaraldehyde as cross-linking agent,GO/starch composite hydrogels with different GO contents and GP/starch composite hydrogels with different graphite powder(GP)contents were designed and prepared.Also,the electric-response of this two kinds of composite hydrogels was compared and studied.And the results showed that the GO(GP)/starch composite hydrogel exhibited positive response to the electric field,and the storage modulus values of the GO(GP)/starch composite hydrogels were decreased first and then increased with the GO(GP)content increased whether with or without the applied electric field.When the addition of GO(GP)content was 1.0 mg/mL,the electric field response of the composite hydrogel reached the maximum value.And comparing the electric field response of the two kinds of composite hydrogels,it was found that the oxygen-containing crown energy group in GO has a great influence on the electric field response performance.2.GO/gelatin composite hydrogels with different GO concentrations of GO of 0,0.25,0.5,0.75,0.1,0.15,0.2,and 0.25 mg/mL were designed and synthesized using gelatin as raw material and glutaraldehyde as crosslinker.The gelation mechanism and electric field response performance were studied.The results show that the storage modulus of the composite hydrogel first decreases and then increases with the addition of GO without applying an electric field;after the application of the electric field,it is consistent with that of the starch composite hydrogels,and show a positive response the externally electric field.,and GO will increase the electrical response of starch hydrogels at specific concentrations.During the study,it was found that the degree of oxidation of GO also had a significant effect on the electrical response of the composite hydrogel.Therefore,comparing the five different degrees of oxidation of the GO/gelatin composite hydrogel,it was found that the addition of GO with different degrees of oxidation was reduced.The storage modulus of gelatin composite hydrogel increase with the increase of GO oxidation degree,its storage modulus under no electric field does not change much,about 17～18 kPa;The higher the degree of GO oxidation,the better the electric field response of the GO/gelatin composite hydrogel.3.Through the overall comparison of the storage modulus(G),storage modulus increment(△G)and storage modulus increment sensitivity(△G/GB)of starch composite hydrogels and gelatin composite hydrogels,it was found that starch composite hydrogels responsiveness better when at high concentrations of graphite oxide,and at the low concentration of graphite oxide gelatin composite hydrogel is better.