Preparation And Characterization Of Alginate-based Foam Sponges

Three kinds of porous calcium alginate（ALG）sponges were prepared by stirring alginate solution to produce a mass of bubbles,including ALG sponges,ALG sponges surface modified by CS（CS-ALG）and ALG-CS polyblend sponges.The porous structure,swelling property,absorbing and remaining water and mechical property of the sponges were tested.Moreover,the antibacterial capacity and loaded silver nano-particles of ALG songes and（CS-ALG）sponges were experimented.The main results in this paper were concluded as following:（1）Soft Al G sponges with excellent flexibility were prepared by impregnating dry alginate sponges into alcohol-glycerol solution.The absorbing and preserving liquid capacity and tensile strength were increased with the increase of alcohol content,but decreased with the increase of glycerol content.However,the nominal strain at break was opposite.Ag NPs-loaded ALG sponges using Ag NO₃ as precursor,alginate and glycerol as reducing agent were prepared only by one step.the sponges showed good antibacterial capability against both Staphylococcus aureus and Escherichia coli.（2）The CS-MMT and CS-Ag-MMT polymer-silicate nanocomposite was prepared by the intercalation of chitosan（CS）or/and Ag⁺into the silicate galleries of montomorillonite（MMT）.CS-ALG sponges and CS-MMT-ALG sponges were prepared by covering CS and CS-MMT on the surface of ALG sponges.Equilibrium swelling degree was decreased after ALG sponges were covered by CS.It had no effect on the equilibrium swelling degree when MMT was added to CS-ALG sponges,but the swelling rate was reduced.The CCD results displayed the absorbing and preserving liquid capacity of CS-ALG sponges and CS-MMT-ALG sponges.The absorbing and preserving liquid capacity was decreased with the increase of CS and glycerol content.In addition,The CCS results showed the tensile strength of CS-ALG sponges was increased with the increase of CS content.When MMT was 0.03g,CS was 0.3%,and glycerol was 6%,the best tensile strength of the sponges reached to0.14MPa.CS-Ag-MMT-ALG sponges showed good antibacterial capability against both Staphylococcus aureus and Escherichia coli.（3）CS-ALG blended sponges with homogeneous structure were prepared by mixing ALG foam liquid with CS foam liquid.The diameter of the pores of the sponges showed increased tendency with the increase of the ratio of alginate and chitosan,the percentage of small pores was increased with the increase of Ca Cl₂ in Ca Cl₂-glycerol solution.The absorbing and preserving liquid capacity to distilled water and normal saline was decreased with the increase of the ratio of alginate and chitosan,and increased with the increase of Ca Cl₂ in Ca Cl₂-glycerol solution.The tensile strength of CS-ALG blended sponges was increased with the increase of chitosan content and Ca Cl₂ content.The maximum tensile strength attained to0.29MPa when the ratio of alginate and CS was 1:1,and the concentration of Ca Cl₂was 0.3%.The absorbing liquid capacity of the three kinds of the sponges can approximately reach to 10 times.