Preparation And Friction Properties Of Double-crosslinked Sodium Alginate/polyacrylamide Hydrogel With High Strength

Sodium alginate has excellent biocompatibility,hydrophilicity and stability,and is easy to chelate with metal ions to form a gel,which is often used to prepare hydrogels.However,the low mechanical properties of traditional sodium alginate hydrogel limit its development and practical application.In recent years,the proposal of doublenetwork hydrogels has improved the shortcomings of low mechanical properties of traditional hydrogels,and greatly improved the tensile strength and compressive strength of hydrogels,and broadened the application range of hydrogels.Another reason that limits the practical application of hydrogels is the lack of systematic research on the friction and wear properties of hydrogels.Friction and wear are the main cause of material damage in a complex force environment.Good friction and wear performance is also an important standard for material application,but there is insufficient research on the friction performance and wear of hydrogels.In order to solve the above problems,this thesis uses sodium alginate(SA)and acrylamide(AM)as raw materials,and uses ion electrostatic interaction and hydrophobic association to prepare a self-healing double cross-linked hydrogel.And the friction and wear properties of hydrogels were systematically studied.Firstly,in this thesis,polyacrylamide(PAM)single network hydrogel,polyacrylamide/sodium alginate(PAM/SA)semi-interpenetrating hydrogel and polyacrylamide/sodium alginate(PAM/SA-Fe)double network hydrogel were prepared.Then the chemical structure and microstructure of the hydrogel were observed by infrared spectroscopy and scanning electron microscope,the results prove that AM and the hydrophobic monomer octadecyl methacrylate(SMA)have copolymerized,and no new chemical bonds are formed between the two interpenetrating networks.Secondly,the tensile and compressive properties of PAM/SA-Fe hydrogel were tested by universal testing machine.The breaking strength of PAM/SA-Fe hydrogel was up to 1.40 MPa,which is 7 times of single network hydrogel,the elongation at break reached 1500%,the compressive strength could reach 6.02 MPa,and the toughness of PAM/SA-Fe hydrogel was high.At the same time,the energy dissipation mechanism of PAM/SA-Fe hydrogels was explored through tensile-retraction experiments and rheological experiments,and it was found that PAM/SA-Fe hydrogels have excellent self-healing properties and fatigue resistance Then the self-healing properties of PAM/SA-Fe hydrogel were studied,and the self-healing efficiency of hydrogel could reach 60% at 70℃.Finally,the swelling properties,thermodynamic properties,PH responsiveness and temperature response of PAM/SA-Fe hydrogels were studied.Finally,with reference to the movement mode of the human body,a systematic study on the friction and wear of hydrogels was carried out.Thirdly,with reference to the movement mode of the human body,a systematic study on the friction and wear of hydrogels was carried out.The friction and wear properties of different types of hydrogels were studied.The effects of different pressures,different speeds,different lubrication conditions,different friction methods,and different sizes of grinding pairs on the friction and wear properties of PAM/SA-Fe hydrogels were also studied.Studies have shown that PAM/SA-Fe hydrogel has a low coefficient of friction and wear,and is suitable for artificial cartilage or cartilage repair materials.The type of hydrogel wear was observed through environmental scanning electron microscopy.The in vitro cytotoxicity test and hemolysis test prove that the above hydrogels have good biological safety and have good application prospects.