本文以壳聚糖为主体材料，在其侧链接枝天然的具有抗氧化作用的芳胺类化合物腺嘌呤来增加它的抗氧化活性，并选用具有更高长径比的纳米纤维素掺杂制备高强度的改性壳聚糖复合膜。通过红外光谱、核磁共振碳谱和元素分析对改性壳聚糖进行结构鉴定，证明了腺嘌呤的接枝成功。抗氧化实验结果表明，腺嘌呤改性后的壳聚糖膜抗氧化活性得到显著提升，DPPH自由基清除率能达到72.20%，而纳米纤维素的掺杂增加了壳聚糖膜的机械性能和尺寸稳定性，MCBC-CNF-2膜的拉伸强度能达到65.06 MPa，吸水率和溶胀率分别仅为36.20%和6.06%，尽管随着纳米纤维素掺杂量的增加，改性壳聚糖膜的抗氧化活性有所降低，但MCBC-CNF-2膜的DPPH自由基清除率仍能达到54.20%。这种全生物质膜科生物降解并且成本较低，有望应用于食品包装材料。

In this paper, an antioxidant composite was prepared using chitosan as the main material. Chitosan was modified by natural aromatic amine compound via grafting reaction and then blended with nanocellulose with higher aspect ratio, forming a new composite material. The structure of the polymer was characterized by FT-IR, 13C NMR and elemental analysis, which proved the success of adenine grafting. The antioxidant test results show that the obtained composite showed much higher strength than both chitosan and cellulose. Antioxidant evaluation also showed that the antioxidant activity of chitosan-based material significantly improved DPPH scavenging capability. The DPPH radical scavenging activity of MCBC membrane can reach 72.20%. And the doping of nanocellulose further increased its mechanical properties and dimensional stability. The tensile strength of MCBC-CNF-2 membrane reached 65.06 MPa, and the water absorption and swelling ratio were only 36.20% and 6.06%, respectively. Although the antioxidant activity of the modified chitosan membrane decreased with the increase of nanocellulose doping amount, the DPPH radical scavenging activity of MCBC-CNF-2 membrane still reached 54.20%. This obtained composite material was biodegradable and cost-effective, which is expected to be applied to food packaging materials.

国家自然科学基金项目(21676105)；制浆造纸工程国家重点实验室项目(201838)