BIM Kemi AB, Box 3102, SE-443 03 Stenkullen, Sweden, Department of Fibre and Polymer Technology, School of Chemical Science and Engineering, The Royal Institute of Technology, SE-100 44 Stockholm, Sweden, and Innventia AB, Box 5604, SE-114 86 Stockholm, Sweden.
Biomacromolecules. 2010 Apr 12;11(4):872-82. doi: 10.1021/bm100075e.
The possibility of forming self-organized films using only charge-stabilized dispersions of cellulose I nanofibrils with opposite charges is presented, that is, the multilayers were composed solely of anionically and cationically modified microfibrillated cellulose (MFC) with a low degree of substitution. The build-up behavior and the properties of the layer-by-layer (LbL)-constructed films were studied using a quartz crystal microbalance with dissipation (QCM-D) and stagnation point adsorption reflectometry (SPAR). The adsorption behavior of cationic/anionic MFC was compared with that of polyethyleneimine (PEI)/anionic MFC. The water contents of five bilayers of cationic/anionic MFC and PEI/anionic MFC were approximately 70 and 50%, respectively. The MFC surface coverage was studied by atomic force microscopy (AFM) measurements, which clearly showed a more dense fibrillar structure in the five bilayer PEI/anionic MFC than in the five bilayer cationic/anionic MFC. The forces between the cellulose-based multilayers were examined using the AFM colloidal probe technique. The forces on approach were characterized by a combination of electrostatic and steric repulsion. The wet adhesive forces were very long-range and were characterized by multiple adhesive events. Surfaces covered by PEI/anionic MFC multilayers required more energy to be separated than surfaces covered by cationic/anionic MFC multilayers.
本文提出了仅使用带有相反电荷的纤维素 I 纳米原纤维的电荷稳定分散体形成自组装膜的可能性，即多层膜仅由低取代度的阴离子和阳离子改性的微原纤化纤维素（MFC）组成。使用石英晶体微天平（QCM-D）和停流点吸附反射测量法（SPAR）研究了层层（LbL）构建膜的堆积行为和性质。比较了阳离子/阴离子 MFC 和聚乙烯亚胺（PEI）/阴离子 MFC 的吸附行为。阳离子/阴离子 MFC 和 PEI/阴离子 MFC 的五个双层的含水量分别约为 70%和 50%。原子力显微镜（AFM）测量研究了 MFC 的表面覆盖率，结果清楚地表明，五个双层的 PEI/阴离子 MFC 比五个双层的阳离子/阴离子 MFC 具有更密集的纤维状结构。使用 AFM 胶体探针技术研究了基于纤维素的多层之间的力。接近时的力由静电和空间排斥的组合来表征。湿粘着力是长程的，其特征是多次粘附有多个附着事件。与由阳离子/阴离子 MFC 多层覆盖的表面相比，由 PEI/阴离子 MFC 多层覆盖的表面需要更多的能量才能分离。
