Liu Lei, Wang Yuxin, Alhassan Saeed M, Sun Hua, Choi Kyungwho, Yu Choongho, Schiraldi David A
Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, OH 44106-7202, USA.
Department of Chemical Engineering, The Petroleum Institute, P.O. Box 2533, Abu Dhabi, United Arab Emirates (UAE).
Gels. 2018 Jan 12;4(1):8. doi: 10.3390/gels4010008.
Dispersion of graphite in water was achieved using clay as dispersing aid. In the absence of polymer, the clay/graphite suspensions were sufficiently stable to produce aerogels composed of very thin layers of uniformly dispersed nanoparticles. Poly(vinyl alcohol) (PVOH) aerogels containing binary nanofillers (clay plus graphite) were then fabricated and tested. These composites were found to maintain low thermal and electrical conductivities even with high loading of graphite. A unique compressive stress-strain behavior was observed for the aerogel, exhibiting a plateau in the densification region, likely due to sliding between clay and graphite layers within the PVOH matrix. The aerogels containing only graphite exhibited higher compressive modulus, yield stress and toughness values than the samples filled with binary nanofillers. X-ray diffraction (XRD) spectra for the same composite aerogel before and after compression testing illustrated the compression-induced dispersion changes of nanofillers. Composites containing 50 wt % graphite demonstrated a downshift of its 2D Raman peak implying graphite exfoliation to graphene with less than 5 layers.
使用粘土作为分散助剂实现了石墨在水中的分散。在没有聚合物的情况下，粘土/石墨悬浮液足够稳定，能够制备出由非常薄的均匀分散纳米颗粒层组成的气凝胶。然后制备并测试了含有二元纳米填料（粘土加石墨）的聚乙烯醇（PVOH）气凝胶。发现这些复合材料即使在高负载石墨的情况下仍能保持较低的热导率和电导率。观察到气凝胶具有独特的压缩应力-应变行为，在致密化区域呈现出一个平台，这可能是由于PVOH基质中粘土和石墨层之间的滑动所致。仅含石墨的气凝胶比填充二元纳米填料的样品表现出更高的压缩模量、屈服应力和韧性值。压缩测试前后相同复合气凝胶的X射线衍射（XRD）光谱说明了纳米填料的压缩诱导分散变化。含有50 wt%石墨的复合材料其二维拉曼峰发生下移，这意味着石墨剥离成了少于5层的石墨烯。
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