Multi-network Hydrogels For Three-Dimendional Printing

Polyacrylamide hydrogel is a kind of biological materials which has been developing very rapidly in recent years.It has been widely used in many fields such as drug release,petrochemical engineering,tissue engineering,etc.With the development of the hydrogel,the traditional processing method has been unable to meet the needs of complex functional structure,and the rapid development of 3D printing technology has solved the original complicated processing problem.Therefore,it is particularly important to prepare hydrogels with excellent mechanical properties and suitable for 3D printing.In the paper,the multi-network polyacrylamide natural polymer hydrogel was obtained by acrylamide,photoinitiator,crosslinker,sodium alginate,gelatin,calcium chloride.In the system,a network system was formed by polymerization of acrylamide with crosslinker and initiator.The second network system can be formed by the crosslinks between sodium alginate and calcium chloride,and the hydrogen bonds in the gelatin are cross-linked to the third network system.At the same time,gelatin is used as a support material for 3D printing.It is rapidly formed by 3D printing technology.In the experiment,the appropriate ratio of hydrogels was found by a single variable method and the tension,pressure,and viscosity were tested later.he results were as follows : When the gelatin content was 20 wt.%,the sodium alginate content was 1.5 wt.%,the acrylamide content was 10 wt.%,and the crosslinker content was 0.05 wt.%,the mechanical properties of the hydrogel were optimal at this time.The tensile strength was 0.2395 Mpa,the compression strength was 1.8915 Mpa,the swelling ratio was 4.96,the elongation was 300.0%,and the viscosity was 11400 mPa·s.At the same time,it was also found that the natural polyacrylamide hydrogels had self-healing properties,when calcium chloride was not cross-linked with sodium alginate.Sodium alginate plays a role in regulating viscosity in the experiment.Based on the previous work,the paper studied the proper ratio of 3D printing for self-healing polyacrylamide hydrogel,and its mechanical properties and self-healingeffect.The experimental results showed that when the gelatin content was 30 wt.%,the acrylamide content was 10 wt.%,and the crosslinker content was 0.05 wt.%,the hydrogel had a tensile strength of 0.1796 MPa,a compression strength of 1.7610 MPa,a swell ratio of 8.50,and a viscosity of 1800 mPa·s,the elongation was 495.5 %.At last,the thesis used the polyacrylamide hydrogel as an adsorbent to adsorb methylene blue,an organic dye molecule in aqueous solution since hydrogels have good swelling properties.Then,the adsorption kinetics were studied.The results showed that the hydrogels obtained by the two parts of the experiment all conformed to the pseudo-second-order kinetic model.