Steric stabilization of a cellulose microcrystal suspension by poly(ethylene glycol) grafting
Steric stabilization of a cellulose microcrystal suspension by poly(ethylene glycol) grafting
复制标题
DOI：
10.1021/la001070m
复制
发表时间：
2001-01-09
期刊：
影响因子：
3.9
通讯作者：
Kuga, S
中科院分区：
文献类型：
--
作者：
Araki, J;Wada, M;Kuga, S
采用天然纤维素酸水解、微晶氧化羧化、一端有末端氨基的聚乙二醇（PEG-NH2, MW = 1000）接枝的方法，制备了具有空间稳定性的棒状纤维素微晶水悬浮液。通过重量增加、羧基减少、热重法和红外光谱证实了PEG与微晶体的化学结合，导致最初引入的羧基消耗了20-30%。结合PEG的量为0.2 ~ 0.3 g/g纤维素。聚乙二醇接枝的纤维素微晶表现出显著增强的分散稳定性，即抗2 M氯化钠的加入，并能从冻干状态再分散到水中或氯仿中。聚乙二醇接枝微晶的浓水悬浮液通过类似于未接枝样品的相分离形成了手性向列中间相，但指纹图谱间距减小。
A sterically stabilized aqueous suspension of rodlike cellulose microcrystals was prepared by the combination of acid hydrolysis of native cellulose, oxidative carboxylation of microcrystals, and grafting of poly(ethylene glycol) having a terminal amino group on one end (PEG-NH2, MW = 1000) using water-soluble carbodiimide. Chemical binding of PEG to the microcrystals was confirmed by weight increase, diminishment of carboxyl groups, thermogravimetry, and infrared spectroscopy, resulting in consumption of 20-30% of the initially introduced carboxyl groups. The amount of bound PEG was 0.2-0.3 g/g of cellulose. The PEG-grafted cellulose microcrystals showed drastically enhanced dispersion stability, that is, resistance to addition of 2 M sodium chloride, and ability to redisperse into either water or chloroform from the freeze-dried state. The concentrated aqueous suspension of PEG-grafted microcrystals formed a chiral nematic mesophase through a phase separation similar to that of the ungrafted sample, but with a reduced spacing of the fingerprint pattern.