明胶基天然高分子/氧化石墨烯复合微胶囊的制备及调湿性能

利用调湿材料的吸放湿性能调节湿度是一种环保节能的被动调湿技术，广泛应用于室内调湿、食品包装、文物保护等领域。采用壳聚糖、液体石蜡、氧化石墨烯(GO)为微胶囊核心材料，利用壳聚糖和GO的静电作用形成类似表面活性剂亲水亲油结构的壳聚糖-GO结合体，在乳化剂和壳聚糖-GO结合体共同作用下乳化获得乳胶束，然后以此乳胶束为模板，采用戊二醛交联法制备了明胶基天然高分子/GO复合微胶囊(M-GO)。考察了GO用量、乳化pH值对乳液胶束粒径和稳定性的影响。在最佳乳化条件下制备了微胶囊，并研究了GO的引入对微胶囊的结构和吸/放湿性能的影响。通过傅立叶红外光谱(FT-IR)、扫描电镜(SEM)、透射电镜(TEM)、氮气吸附对微胶囊的结构进行表征，通过测试微胶囊吸湿率和放湿率研究其调湿性能。结果表明，当GO用量为3 mL (1 mg/mL)、乳化pH值为5.10时，乳化形成的乳液粒径均匀且乳液的稳定性较好。GO与壳聚糖、明胶相互作用成功制备了微胶囊，未引入GO的微胶囊呈封闭的微球结构，当引入GO后所得的微胶囊M-GO为壳层开孔的中空结构，具有较大的比表面积和孔体积，有利于对水分的吸附。M-GO在不同湿度下的饱和吸湿量、吸湿/放湿率均优于未引入GO微胶囊，说明GO通过改变微胶囊的微结构、增加吸附水分的表面积，从而能够提高调湿性能。

Preparation and humidity-regulation performance of gelatin based natural polymer/graphene oxide composite microcapsules

It is an environmental friendly and energy saving passive humidity regulation technology to use humidity control materials, which has been widely used in indoor humidity control, food packaging, cultural relic protection and other fields. The chitosan, liquid paraffin and graphene oxide were used as the microcapsule core materials. The surfactant-like hydrophilic and oleophilic chitosan-graphene oxide complex was formed by the electrostatic interaction between chitosan and graphene oxide. And the emulsion micelle was obtained emulsified by the combined assistance of emulsifier and chitosan-graphene oxide complex. Then using the emulsion micelle as template, the gelatin-based natural polymer/graphene oxide composite microcapsules (M-GO) were fabricated by the crosslinking of glutaraldehyde. The influence of graphene oxide dosage and emulsifying pH value on the micelle size and stability of emulsion was investigated. The microcapsules were obtained under the optimal emulsifying condition. The effect of graphene oxide on the structure and moisture adsorption/desorption performance of microcapsules were studied. The as-prepared microcapsules were characterized by Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N2 adsorption-desorption isotherms. The humidity-regulation performance was studied by measuring the moisture absorption and desorption rates. The results showed that emulsion micelle size was uniform with good stability when the dosage of graphene oxide was 3 mL (1 mg/mL) and the emulsifying pH value was 5.10. The results indicated that the microcapsules were successfully prepared by the interaction between graphene oxide, chitosan and gelatin. The microcapsule without graphene oxide showed a closed microsphere structure. After introducing graphene oxide, the microcapsule M-GO exhibited an open hollow shell and had larger surface area and pore volume, which was beneficial to adsorption moisture. The saturated moisture content and adsorption/desorption rate of M-GO in different humidity conditions were better than those of microcapsules without graphene oxide. It indicated that the introduction of graphene oxide can improve humidity-regulation performance by changing the microstructure and increasing the surface area for adsorbing moisture.