Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, China.
Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Department of Chemistry, Tsinghua University , Beijing 100084, China.
J Am Chem Soc. 2017 Sep 13;139(36):12517-12523. doi: 10.1021/jacs.7b05490. Epub 2017 Aug 30.
The properties and functions of graphene oxide (GO)-based materials strongly depend on the lateral size and size distribution of GO nanosheets; therefore, GO and its derivatives with narrow size distributions are highly desired. Here we report the size fractionation of GO nanosheets by controlled directional freezing of GO aqueous dispersions. GO nanosheets with a narrow size distribution can be obtained by controlling the growth rate of the freezing front. This interesting phenomenon can be explained by the adsorption of GO nanosheets on the ice crystal surface in combination with the stratification of GO nanosheets at the ice growth front. Such a convenient size fractionation approach will be essential for practical applications of chemically modified graphene, including GO, reduced GO, and their assemblies or composites.
氧化石墨烯（GO）基材料的性质和功能强烈依赖于 GO 纳米片的横向尺寸和尺寸分布；因此，具有较窄尺寸分布的 GO 及其衍生物是非常需要的。在这里，我们通过控制 GO 水基分散体的定向冷冻来实现 GO 纳米片的分级分离。通过控制冷冻前沿的生长速率，可以得到具有较窄尺寸分布的 GO 纳米片。这种有趣的现象可以通过 GO 纳米片在冰晶表面的吸附与 GO 纳米片在冰生长前沿的分层相结合来解释。这种方便的分级分离方法对于化学修饰石墨烯（包括 GO、还原 GO 及其组装体或复合材料）的实际应用至关重要。
