Jordan Jacobs H, Easson Michael W, Condon Brian D
The Southern Regional Research Center, Agricultural Research Service, USDA, 1100 Robert E. Lee Blvd., New Orleans, LA 70124, USA.
Nanomaterials (Basel). 2019 Aug 30;9(9):1232. doi: 10.3390/nano9091232.
Cellulose nanocrystals (CNCs) are a biorenewable resource, which may be chemically modified to impart specific properties. Modified CNCs have found use in imaging applications, as rheology modifiers, polymer reinforcements, barrier and/or optical films, and nanocomposites. Nanoparticle dimensions of CNCs are typically 5-10 nm in width, with lengths of <100-300 nm. However, the physical properties are dependent upon the number and nature of the surface charge groups imparted during preparation. In the case of CNCs produced from sulfuric acid hydrolysis, the sulfated surface groups may be partially removed prior to further functionalization. This gives more available hydroxyls yet renders the CNCs less colloidally stable. Furthermore, conditions vary significantly and there is no consensus about the optimal conditions for partial removal of sulfate functionality or conditions developed to give specific surface charge. In the following, alkali hydrolysis of sulfate half-esters was quantified by conductometric titration of the strong acid groups, and using a design of experiments (DOE), optimal conditions were determined to produce CNCs with tailored surface charge.
纤维素纳米晶体（CNCs）是一种生物可再生资源，可通过化学修饰赋予其特定性能。改性CNCs已应用于成像、流变学改性剂、聚合物增强材料、阻隔和/或光学薄膜以及纳米复合材料等领域。CNCs的纳米颗粒尺寸通常宽度为5-10纳米，长度小于100-300纳米。然而，其物理性质取决于制备过程中赋予的表面电荷基团的数量和性质。对于由硫酸水解制备的CNCs，在进一步功能化之前，硫酸化表面基团可能会被部分去除。这会产生更多可用的羟基，但使CNCs的胶体稳定性降低。此外，条件差异很大，对于部分去除硫酸盐官能团的最佳条件或产生特定表面电荷的条件尚无共识。在此，通过对强酸基团进行电导滴定来定量硫酸盐半酯的碱水解，并使用实验设计（DOE）确定了制备具有定制表面电荷的CNCs的最佳条件。
