School of Renewable Natural Resources, Louisiana State University AgCenter, Baton Rouge, Louisiana 70803, United States.
Biomacromolecules. 2013 May 13;14(5):1529-40. doi: 10.1021/bm4001734. Epub 2013 Apr 12.
Cellulose nanocrystals and cellulose nanofibers with I and II crystalline allomorphs (designated as CNC I, CNC II, CNF I, and CNF II) were isolated from bleached wood fibers by alkaline pretreatment and acid hydrolysis. The effects of concentration, particle size, surface charge, and crystal structure on the lyophilization-induced self-assembly of cellulose particles in aqueous suspensions were studied. Within the concentration range of 0.5 to 1.0 wt %, cellulose particles self-organized into lamellar structured foam composed of aligned membrane layers with widths between 0.5 and 3 μm. At 0.05 wt %, CNC I, CNF I, CNC II, and CNF II self-assembled into oriented ultrafine fibers with mean diameters of 0.57, 1.02, 1.50, and 1.00 μm, respectively. The size of self-assembled fibers became larger when more hydroxyl groups and fewer sulfates (weaker electrostatic repulsion) were on cellulose surfaces. Possible formation mechanism was inferred from ice growth and interaction between cellulose nanoparticles in liquid-crystalline suspensions.
纤维素纳米晶和纤维素纳米纤维的 I 和 II 晶型（分别指定为 CNC I、CNC II、CNF I 和 CNF II）是通过碱性预处理和酸水解从漂白木纤维中分离出来的。研究了浓度、粒径、表面电荷和晶体结构对水悬浮液中冻干诱导纤维素颗粒自组装的影响。在浓度为 0.5 到 1.0 重量%的范围内，纤维素颗粒自组装成层状结构的泡沫，由宽度在 0.5 到 3 微米之间的定向膜层组成。在 0.05 重量%时，CNC I、CNF I、CNC II 和 CNF II 自组装成取向的超细纤维，平均直径分别为 0.57、1.02、1.50 和 1.00 微米。当纤维素表面的羟基越多、硫酸酯越少（静电排斥力越弱）时，自组装纤维的尺寸就会越大。根据冰晶生长和液晶悬浮液中纤维素纳米颗粒之间的相互作用，推断出可能的形成机制。
