Department of Forest Biomaterials, North Carolina State University, Raleigh, North Carolina 27695-8005, USA.
Langmuir. 2010 Jan 19;26(2):990-1001. doi: 10.1021/la902444x.
Model cellulose surfaces based on cellulose nanocrystals (CNs) were prepared by the Langmuir-Schaeffer technique. Cellulose nanocrystals were obtained by acid hydrolysis of different natural fibers, producing rodlike nanoparticles with differences in charge density, aspect ratio, and crystallinity. Dioctadecyldimethylammonium bromide (DODA-Br) cationic surfactant was used to create CN-DODA complexes that allowed transfer of the CNs from the air/liquid interface in an aqueous suspension to hydrophobic solid substrates. Langmuir-Schaeffer horizontal deposition at various surface pressures was employed to carry out such particle transfer that resulted in CN monolayers coating the substrate. The morphology and chemical composition of the CN films were characterized by using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Also, their swelling behavior and stability after treatment with aqueous and alkaline solutions were studied using quartz crystal microgravimetry (QCM). Overall, it is concluded that the Langmuir-Schaeffer method can be used to produce single coating layers of CNs that were shown to be smooth, stable, and strongly attached to the solid support. The packing density of the films was controlled by selecting the right combination of surface pressure during transfer to the solid substrate and the amount of CNs available relative to the cationic charges at the interface.
基于纤维素纳米晶体（CNs）的模型纤维素表面通过 Langmuir-Schaeffer 技术制备。通过不同天然纤维的酸水解获得纤维素纳米晶体，产生带不同电荷量、纵横比和结晶度的棒状纳米颗粒。使用双十八烷基二甲基溴化铵（DODA-Br）阳离子表面活性剂来制备 CN-DODA 配合物，允许将 CNs 从空气/液体界面转移到水悬浮液中的疏水性固体基底上。采用 Langmuir-Schaeffer 水平沉积在不同的表面压力下进行这种颗粒转移，从而导致 CN 单层覆盖基底。使用原子力显微镜（AFM）和 X 射线光电子能谱（XPS）对 CN 薄膜的形貌和化学组成进行了表征。还使用石英晶体微天平（QCM）研究了它们在水和碱性溶液处理后的溶胀行为和稳定性。总的来说，结论是 Langmuir-Schaeffer 方法可用于生产单涂层的 CNs，这些 CNs 表现出光滑、稳定和与固体支撑物牢固结合的特性。通过选择在转移到固体基底时的正确表面压力组合以及相对于界面上的阳离子电荷的可用 CNs 量来控制薄膜的堆积密度。
