Department of Chemistry, McGill University, Pulp and Paper Building, 3420 University Street, Montréal, Québec H3A 2A7, Canada.
Langmuir. 2010 Aug 17;26(16):13450-6. doi: 10.1021/la101795s.
Aqueous suspensions of poly(ethylene oxide)-grafted nanocrystalline cellulose (PEO-grafted NCC) were prepared in order to achieve steric instead of electrostatic stabilization. A two-step process was employed: in the first step NCC suspensions prepared by sulfuric acid hydrolysis were desulfated with sodium hydroxide, and in the second step the surfaces of the crystals were functionalized with epoxy-terminated poly(ethylene oxide) (PEO epoxide) under alkaline conditions. The PEO-grafted samples were analyzed by conductometric titration, ATR-IR, solid-state NMR, MALDI-TOF MS, SEC MALLS, and AFM. The covalent nature of the linkage was confirmed by weight increase and MALDI-TOF analysis. The PEO-grafted cellulose nanocrystals (CNCs) formed a stable colloidal suspension that remained well dispersed, while the desulfated nanoparticles aggregated and precipitated. Upon concentration of the PEO-grafted aqueous NCC suspension, a chiral nematic phase was observed.
为了实现空间稳定而不是静电稳定，制备了接枝聚氧化乙烯（PEO）的纳米纤维素晶须（PEO 接枝 NCC）的水悬浮液。采用两步法：第一步，用硫酸水解制备 NCC 悬浮液，然后用氢氧化钠脱硫酸根；第二步，在碱性条件下，用端环氧聚氧化乙烯（PEO 环氧化物）对晶体表面进行功能化。通过电导率滴定、ATR-IR、固态 NMR、MALDI-TOF MS、SEC-MALLS 和 AFM 对 PEO 接枝样品进行了分析。通过重量增加和 MALDI-TOF 分析证实了键的共价性质。PEO 接枝纤维素纳米晶（CNCs）形成了稳定的胶体悬浮液，保持良好的分散状态，而脱硫酸根的纳米颗粒则聚集和沉淀。当 PEO 接枝水基 NCC 悬浮液浓缩时，观察到手性向列相。
