Synthesis And Properties Of Alginate Hydrogel

Multifunction intelligence hydrogels not only have the traditional properties of the hydrogels,such as high water absorption and high mechanical strength,but also have other performances,such as thermosensitivity,p H-sensitivity,freezing resistance and pressure resistance performance.In this paper,bimetallic ions cross-linked alginate hydrogels were prepared with sodium alginate as materials,and the Ca²⁺and Zn²⁺ions as cross-linkers.The effects of ions concentration and cross-linked time on the swelling ratios and mechanical strength are studied.We designed and prepared robust and tough alginate hydrogels（GMA-SA-PAM）using the ingenious strategy of fully interpenetrating crosslinking,in which the glycidyl methacrylate（GMA）was used as a bridge to link alginate with acrylamide（AM）through covalent bonds for the fabrication of high strength modified alginate hydrogels.The homogeneous network constructed from modified alginate and acrylamide contributes to the strength and elasticity of hydrogels.GSP-Na hydrogel with electrochemical properties without loss of mechanical strength was obtained by soaking GMA-SA-PAM hydrogel in NaCl solution.Strong mechanical strength and excellent electrical conductivity will make GSP-Na hydrogels have greater development potential in the field of electrochemical applications.1.The Ca²⁺cross-linked alginate hydrogel was successfully prepared,and effect of the cross-link time on the compressive strength of hydrogel was investigated,the cross-link time was selected as 24 h.With Zn²⁺ions as the second crosslinker,the Ca²⁺and Zn²⁺ions double cross-linked alginate hydrogel displays excellent frost resistance.When the temperature at 25℃and-18℃,the compressive strengths of hydrogels were118.88 KPa,97.3 KPa,and the elongations were 142%and 129%,respectively.The experiment result indicates that hydrogels still have good mechanical properties when the temperature at-18℃.2.With SA and AM as materials,N,N-methylenebisacrylamide（BIS）as crosslinker,a series of composite SA-PAM hydrogels with combined features were fabricated.SA-PAM hydrogel display excellent swelling property and moderate crosslinking density which BIS dosage was 1 W_t%and 2 W_t%.When the BIS dosage is 1 W_t%,the SA-PAM hydrogels display compression strength and tensile strength of hydrogel was 4.6 KPa and 0.59 MPa,and the elongation at break was 368.3%.3.Using Ca²⁺cross-linked the SA-PAM hydrogel,Ca-SA-PAM hydrogels with fully interpenetrating network structure were successfully prepared.The Ca-SA-PAM hydrogels display ultra-stretchable（strain up to²09%of tensile strain）,tensile strength（0.77MPa）and highly compressible（²6.37 KPa of compression strength）properties.4.The alginate was modified with GMA,the grafting ratio of GMA-SA hydrogel was 20.45%.5.Using the ingenious strategy of fully interpenetrating crosslinking,the robust and tough alginate hydrogels（GMA-SA-PAM）were prepared,in which the GMA-SA copolymerized with AM,BIS as cross-linker.The complete cross-linked structures can average dissipating energy and polymerized structures can maintain hydrogel three-dimensional to greatly improve the mechanical performance of hydrogels.The GMA-SA-PAM hydrogels display ultra-stretchable（strain up to⁴07%of tensile strain,tensile strength 0.86MPa）and highly compressible(compression strength 21.63 KPa properties.6.In addition,soaking the GMA-SA-PAM hydrogel in 5 W_t%NaCl solution also endows the hydrogel（GSP-Na）with excellent conductivity properties（5.26 s*m-1）.The GSP-Na hydrogel with high stability,durability,as well as wide range extent sensor,is also demonstrated by researching the electro-chemical signals,showing the potential for applications in wearable and quickly responded electronics.