Pokharel Pashupati, Lee Dai Soo
J Nanosci Nanotechnol. 2014 Aug;14(8):5718-21. doi: 10.1166/jnn.2014.8824.
Reduced graphene oxide (RGO) based polyurethane (PU) nanocomposites have been successfully prepared without using solvent by in-situ polymerization. RGO was derived from microwave (MW) irradiation of graphite oxide (GO) powder prepared by a modified Hummer's method. A minimum amount of poly(tetramethylene glycol) (PTMEG) was added during the dispersion of RGO in a solvent to stabilize the graphene sheets and to prevent RGO from the restacking after the removal of the solvent. After the reaction of RGO with 4,4'-diphenylmethane diisocyanate (MDI), we obtained the concentrate of RGO in MDI with a minimum amount of PTMEG. Our method facilitated the fine dispersion of RGO in PU elastomers and improved the interfacial strength between RGO and PU. With the incorporation of 2.0 wt% of RGO, the tensile strength and Young's modulus of the PU nanocomposites increased by 30% and 50%, respectively without sacrificing the elongation at break. It was found that the crystalline portion of hard segments of the PU was lowered by the RGO in the nanocomposites.
通过原位聚合成功制备了基于还原氧化石墨烯（RGO）的聚氨酯（PU）纳米复合材料，且未使用溶剂。RGO由采用改进的Hummer法制备的氧化石墨（GO）粉末经微波（MW）辐照得到。在将RGO分散于溶剂过程中加入少量聚四亚甲基二醇（PTMEG），以稳定石墨烯片层，并防止去除溶剂后RGO重新堆叠。RGO与4,4'-二苯基甲烷二异氰酸酯（MDI）反应后，得到含有少量PTMEG的RGO在MDI中的浓缩物。我们的方法有助于RGO在PU弹性体中良好分散，并提高RGO与PU之间的界面强度。加入2.0 wt%的RGO时，PU纳米复合材料的拉伸强度和杨氏模量分别提高了30%和50%，同时不牺牲断裂伸长率。研究发现，纳米复合材料中的RGO降低了PU硬段的结晶部分。
