基于共混和层层自组装方法协同交联剂对琼胶/海藻酸钠复合膜性能的影响

Effect of synergistic crosslinking agent based on blending and layer-by-layer assembly method on properties of agar/sodium alginate composite film

以琼胶和海藻酸钠为成膜基质,通过共混和层层自组装两种方法制备了琼胶/海藻酸钠共混膜和双层膜,并引入交联剂柠檬酸和阿魏酸,通过测定复合膜的机械强度、耐水性、热稳定性、傅里叶变换红外光谱(Fourier transform infrared spectrometer,FT-IR)和微观结构等指标,探究了不同制膜方式结合交联剂对复合膜性能的影响。结果表明,与共混膜相比,双层膜表现出更优异的机械性能和耐水性,添加交联剂后,膜的水蒸气透过率(P<0.05)显著降低,拉伸强度、热稳定性和不透明度提高。其中柠檬酸交联的双层膜综合性能最佳,即拉伸强度51.57 MPa,断裂伸长率26.02%,水溶性24.42%,溶胀率101.67%。FT-IR分析表明柠檬酸通过与琼胶和海藻酸钠发生酯化反应形成CO进行共价交联,而阿魏酸通过与成膜基质形成氢键进行非共价交联。扫描电镜分析表明琼胶和海藻酸钠的相容性良好,各膜表面均平整、光滑,而添加交联剂后,膜截面褶皱减少,膜结构更加紧密。由此表明,层层自组装技术和交联剂的结合使用可以制备出综合性能更好的复合膜。

Agar/sodium alginate blend films and bilayer films were prepared by direct mixing and layer-by-layer assembly,and the cross-linking agents involving citric acid and ferulic acid were introduced.By investigating the mechanical strength,water resistance,thermal stability,Fourier transform infrared spectrometer(FT-IR),and microstructure of the composite films,the effects of different film-making methods combined with cross-linking agents on the properties of the composite films were explored.Results showed that compared with the blend films,the bilayer films showed better mechanical properties and water resistance.After adding crosslinking agents,the water vapor permeability of the films decreased significantly(P<0.05)and the tensile strength,thermal stability,and opacity increased.Among them,citric acid crosslinked bilayer film had the best comprehensive properties,namely,tensile strength of 51.57 MPa,elongation at break of 26.02%,water solubility of 24.42%,and swelling rate of 101.67%.FT-IR analysis showed that citric acid was covalently crosslinked by esterification with seaweed polysaccharide to form C O,while ferulic acid was noncovalently crosslinked by hydrogen bonding with the film-forming substrate.SEM analysis showed that agar and sodium alginate had good compatibility,and the surface of each film was flat and smooth.After adding a crosslinking agent,the cross-sections of the films were smoother and the structure of the films was more compact.Therefore,the combination of layer-by-layer assembly and crosslinking agents can prepare a composite membrane with better comprehensive properties.