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氧化石墨烯/聚合物纳米复合材料的制备与表征
【作者】 王晓燕；
【导师】 刘天西；
【作者基本信息】 复旦大学 ， 高分子化学与物理， 2010， 硕士
【摘要】 石墨烯是具有单原子厚度的碳原子层,C-C之间通过共价键相连接,它可以包裹形成零维的富勒烯,卷曲形成一维的碳纳米管,也可以叠加形成三维的石墨。石墨烯的出现改变了人们对二维物质在常温下无法存在的观点,它在电学、力学以及热学等方面都表现出优异的性能,从而引起人们广泛的关注,并在晶体管、纳米电子器件以及新型高性能电池等方面具有广泛的应用。本文通过超声分散方法制备了具有单层结构的氧化石墨烯,并分别与聚乙烯醇和壳聚糖通过物理化学相互作用制备出性能良好的纳米复合材料。(1)对比热解膨胀和超声分散两种制备氧化石墨烯的方法。结果表明,热解氧化石墨后不能完全实现单层的剥离,片层中仍存在大量多片层结构,且得到的膨胀石墨中化学活性基团大大减少,限制了其在高分子复合材料中的应用；而超声剥离后则能够在不破坏其化学活性的基础上,大量制备出剥离比较完全的单片层氧化石墨烯,拓宽了石墨烯在复合材料中的应用。(2)通过层层自组装方法制备聚乙烯醇／氧化石墨烯纳米复合超薄膜。聚乙烯醇和氧化石墨烯通过氢键相结合,XRD和UV结果均表明,GO在溶液中分散良好,并能与聚乙烯醇之间发生层层吸附,按照一定的结构构筑单元表现出规律性变化,实现了氧化石墨烯在聚乙烯醇基体中的高度取向,成功获得了(PVA/GO)n纳米复合超薄膜。(3)通过溶液共混法制备了壳聚糖／氧化石墨烯的纳米复合材料。TEM以及拉伸测试等结果均表明,氧化石墨烯纳米粒子在壳聚糖基体中能够分散良好,且氧化石墨烯的加入能够使壳聚糖纳米复合材料的拉伸强度和模量显著提高,但另一方面,却也使复合材料的断裂伸长率或韧性下降。
【Abstract】 Graphene sheets, two-dimensional one-atom-thick layers of sp2-bonded carbon, have attracted tremendous attention from the experimental and theoretical communities. It can form zero-dimensional fullerenes, one-dimensional carbon nanotube and three-dimensional graphite. Graphene has changed the opinion that two-dimensional material can not exist at room temperature. It has a wide application in the transistors, nano-electronic devices, batteries for the outstanding electrical, mechanical and thermal properties. In this thesis, a single-layer structure of graphene oxide was prepared by sonicating and two different types of nanocomposites based on graphene were respectively obtained with poly(vinyl alcohol) and chitosan.(1)By comparing thermal expansion and ultrasonication methods, it can be observed that pyrolytic graphite can not be exfoliated to single layer graphene. The chemically active groups were greatly reduced due to the thermal expansion process and thus the applications of graphene in polymer composites were limited. After sonicating, however, graphene oxide was exfoliated to single layer with the chemically active groups, which can find wide applications in polymer nanocomposites.(2) (PVA/GO)n ultrathin film composites were prepared via layer-by-layer (LBL) self-assembly technique. UV-vis and XRD results indicated that GO could readily form ordered ultrathin films with PVA at molecular level owing to strong hydrogen bonding interaction between them. High orientation of graphene oxide in PVA matrix was achieved through such a self-assembly. Therefore, it offers an approach to fabricate a plenty of composite films based on water-soluble polymers and graphene oxide.(3) Chitosan/graphene oxide composites were prepared by solution blending. TEM and tensile test results showed that the graphene oxide was well dispersed in chitosan. Tensile strength and modulus of the nanocomposites were significantly increased, while the elongation at break of the nanocomposites was decreased.