Xu Dingfeng, Wang Shennan, Berglund Lars A, Zhou Qi
Division of Glycoscience, Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Centre, Stockholm SE-106 91, Sweden.
Wallenberg Wood Science Center, Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden.
ACS Appl Mater Interfaces. 2021 Jan 27;13(3):4463-4472. doi: 10.1021/acsami.0c18594. Epub 2021 Jan 11.
The interfacial bonding and structure at the nanoscale in the polymer-clay nanocomposites are essential for obtaining desirable material and structure properties. Layered nanocomposite films of cellulose nanofibrils (CNFs)/montmorillonite (MTM) were prepared from the water suspensions of either CNFs bearing quaternary ammonium cations (Q-CNF) or CNFs bearing carboxylate groups (TO-CNF) with MTM nanoplatelets carrying net surface negative charges by using vacuum filtration followed by compressive drying. The effect of the ionic interaction between cationic or anionic charged CNFs and MTM nanoplatelets on the structure, mechanical properties, and flame retardant performance of the TO-CNF/MTM and Q-CNF/MTM nanocomposite films were studied and compared. The MTM nanoplatelets were well dispersed in the network of TO-CNFs in the form of nanoscale tactoids with the MTM content in the range of 5-70 wt %, while an intercalated structure was observed in the Q-CNF/MTM nanocomposites. The resulting TO-CNF/MTM nanocomposite films had a better flame retardant performance as compared to the Q-CNF/MTM films with the same MTM content. In addition, the effective modulus of MTM for the TO-CNF/MTM nanocomposites was as high as 129.9 GPa, 3.5 times higher than that for Q-CNF/MTM (37.1 GPa). On the other hand, the Q-CNF/MTM nanocomposites showed a synergistic enhancement in the modulus and tensile strength together with strain-to-failure and demonstrated a much better toughness as compared to the TO-CNF/MTM nanocomposites.
聚合物-粘土纳米复合材料中纳米尺度的界面结合和结构对于获得理想的材料和结构性能至关重要。通过真空过滤随后进行压缩干燥，由带有季铵阳离子（Q-CNF）的纤维素纳米纤丝（CNF）或带有羧酸根基团（TO-CNF）的CNF的水悬浮液与带有净表面负电荷的蒙脱土（MTM）纳米片制备了纤维素纳米纤丝（CNF）/蒙脱土（MTM）的层状纳米复合薄膜。研究并比较了带阳离子或阴离子电荷的CNF与MTM纳米片之间的离子相互作用对TO-CNF/MTM和Q-CNF/MTM纳米复合薄膜的结构、力学性能和阻燃性能的影响。MTM纳米片以纳米级准晶体的形式很好地分散在TO-CNF的网络中，MTM含量在5-70 wt%范围内，而在Q-CNF/MTM纳米复合材料中观察到插层结构。与具有相同MTM含量的Q-CNF/MTM薄膜相比，所得的TO-CNF/MTM纳米复合薄膜具有更好的阻燃性能。此外，TO-CNF/MTM纳米复合材料中MTM的有效模量高达129.9 GPa，比Q-CNF/MTM的有效模量（37.1 GPa）高3.5倍。另一方面，与TO-CNF/MTM纳米复合材料相比，Q-CNF/MTM纳米复合材料在模量、拉伸强度以及断裂应变方面表现出协同增强，并且韧性要好得多。
