Department of Polymer Science & Engineering, Kyungpook National University, #1370 Sankyuk-Dong, Buk-gu, Daegu 702-701, Republic of Korea.
ACS Appl Mater Interfaces. 2012 Sep 26;4(9):4623-30. doi: 10.1021/am300999g. Epub 2012 Sep 4.
Chemically modified graphene sheets were dispersed in a high-performance polyimide (PI) matrix using polyamic acid (PAA)/graphene nanocomposite as a precursor. PI nanocomposite films with different loadings of graphene sheets were prepared by thermal imidization of the as-prepared PAA/graphene nanocomposites. Graphene oxide (GO) synthesized by Hummer's method was chemically reduced with various reducing agents to produce reduced GOs (rGOs). The incorporation of only 5 wt% GO resulted in an ~12-fold and ~18-fold increase in the tensile strength and tensile modulus of PI, respectively, while the PI/rGO nanocomposites were found to have relatively inferior tensile properties. The superior mechanical properties of the PI/GO nanocomposites were attributed to the good dispersion and effective stress transfer between the polymer and GO sheets, as evidenced by the results from X-ray diffraction (XRD) and morphological studies. Furthermore, the PI/GO nanocomposites exhibited higher loading capacity than PI/rGO. The thermo-oxidative stability of PI was also remarkably improved with the addition of both GO and rGOs, but rGOs had a more pronounced effect. The electrical conductivity of PI/rGO nanocomposites was higher than that of PI/GO, suggesting restoration of the graphene basal plane upon the reduction of GO. The highest electrical conductivity was achieved for the l-ascorbic acid reduced GO-reinforced PI nanocomposites.
采用聚酰胺酸（PAA）/氧化石墨烯（GO）纳米复合材料作为前驱体，将化学改性的石墨烯片分散在高性能聚酰亚胺（PI）基体中。通过对所制备的 PAA/GO 纳米复合材料进行热酰亚胺化，制备了不同 GO 片层负载量的 PI 纳米复合材料薄膜。采用 Hummers 法合成的 GO 通过各种还原剂进行化学还原，得到还原氧化石墨烯（rGO）。仅加入 5wt%的 GO 就使 PI 的拉伸强度和拉伸模量分别提高了约 12 倍和 18 倍，而 PI/rGO 纳米复合材料的拉伸性能相对较差。PI/GO 纳米复合材料具有优异的力学性能，这归因于聚合物和 GO 片之间良好的分散和有效应力传递，这可从 X 射线衍射（XRD）和形貌研究结果得到证明。此外，PI/GO 纳米复合材料的载药量高于 PI/rGO。添加 GO 和 rGOs 均可显著提高 PI 的热氧化稳定性，但 rGOs 的影响更为显著。PI/rGO 纳米复合材料的电导率高于 PI/GO，表明 GO 的还原恢复了石墨烯基面。电导率最高的是 L-抗坏血酸还原的 GO 增强 PI 纳米复合材料。
