Study On High-strength Gels And Smart Gel Devices

At present,hydrogels and smart gel materials have been widely concerned and applied in many fields.However,the internal structure of traditional hydrogels are not uniform and lack of effective energy dissipation mechanism,resulting in poor mechanical properties.At the same time,in terms of functionalization of gel materials,its unique structural characteristics make it more advantageous in many aspects.Through improvements,the researchers have prepared and synthesized a series of high-strength hydrogels and smart gel devices,which can be used in biological engineering scaffolds,artificial muscles,software robots and electro-stimulus-controlled actuators.In this thesis,the main research purposes are to synthesize high-intensity hydrogel and controllable driving motion intelligent gel device.Achieved the following research goals:In order to achieve the purpose of enhancing and toughening hydrogels,we are based on the synthesis process of double-network hydrogel.The traditional hydrophobically-associated hydrogel is used as the first network.The octadecyl acrylate(SA)and Acrylic acid(MA)as monomers during the synthesis process.cetyltrimethylammonium bromide(CTAB)was used as cationic surfactant,ammonium persulfate(APS)and sodium metabisulfite(SMS)as the initiator system,The single network hydrophobic associating hydrogels were obtained by micelles polymerization in sodium bromide(NaBr)solution.By adjusting the ratio of monomer to surfactant,the gel tensile strength reaches 4.5 MPa and the tearing energy reaches 16.6 kJ·m-2.After the single network gel was immersed in the solution containing N-isopropyl acrylamide(NIPAM)and photoinitiator,the double network hydrogel was obtained.At this point,the gel contains hydrophobic interactions,electrostatic interactions between charged groups and hydrogen bonds formed by amide groups and PMA carboxyl groups.The two networks are entangled with each other,so that the double-network hydrogel exhibits high strength and excellent tear resistance,the tensile strength of the gel reaches 13.6 MPa,the tearing energy can reach 35.01 kJ·-2,and the sample is simultaneously being subjected to freezing treatment,heat treatment,drying and swelling,and immersed in an ethanol solution,The double network shows better resistance to external environment and resistance to swelling of organic solvents.Based on the high-strength double-network hydrogel,we added a flexible polyacrylamide chain to prepare a three-network hydrogel.The double-network gel was immersed in an aqueous solution containing acrylamide and a photoinitiator and form third network inside the gel by photoinitiating polymerization.At this time,the hydrophobic interaction,electrostatic attraction and hydrogen bonding in the network are more coMPact.The three networks inside the gel are more tighter,the tighter entanglement leads to the decrease of water content in the three-network hydrogels,but the mechanical properties are more excellent,it is better to resist the external environment and resist the swelling of the organic solvent.Design gel smart devices.PDMS-CB-C20 film and SEBS-CB-C20 film were prepared separately.After being combined with polyimide(PI)films,the smart gel devices were obtained.Through temperature sensitivity-density curve and DSC curve analysis,the gel device has a significant density change around the melting point of eicosane(36.8?),which coincided with the temperature range of the crystallization peak and melting peak in the DSC curve.The near-field infrared laser is used to locally heat the material and the infrared imager FLUKE Ti110 is used for temperature measurement.The results show that the gel material can rapidly heat up to a sufficient temperature during laser irradiation,and when the light source leaves,the temperature decreases rapidly,which makes the response process of the gel material is performed at a faster rate.