Rheological and electron microscopic characterization of aqueous carboxymethyl cellulose gels Part II: Visualization of the gel structure by freeze-fracturing

Abstract

The spatial structure of gels of sodium carboxymethyl cellulose (NaCMC-gel) and carboxymethyl cellulose in the free acid form can be imaged in the transmission electron microscope (TEM). The freeze-fracturing technique is suitable for this. Experiments with test preparations (10 % aqueous glycerol solution) show that cooling rates during freeze-fixing are decisive for visualization, and that cooling rates can be improved substantially by using a cryojet. The increase of the cooling rate to more than 15 000 K/s makes it possible to obtain extremely fine network structures with a mesh width of 5-25 nm and with a filament thickness of 2-3 nm. The results obtained after jet-freezing show differences in the structure of the two gels: quasi-crystalline microaggregates in the HCMC-gel can be seen, and they cause an increased elasticity and opalescence of the aged HCMC-gels.

Critical roles of binders and formulation at multiscales of silicon-based composite electrodes

“…20e30 nm), as seen in Fig. 6 [24,25]. Note that the maximum stretching value before breaking of threads of a few chains could be different from the one of a massive (bulky) film.…”

“…Copyright (2003), with permission from Elsevier. (b) Visualization of the gel structure of a 1.5% HCMC gel in water after freeze-fracturing[25]. With kind permission from Springer Science and Business Media.…”

A technique for labelling the sample surface for quick‐freeze, deep‐etch, rotary replication electron microscopy: application to the study of geletin gel structure

“…Most previous studies on gel structure were carried out using preparation techniques which could introduce artifacts into the observed specimen geometry as well as disturb the fragile components in their natural configuration. The limitations imposed by preparation methods such as chemical fixation, negative staining, cryoprotective pretreatment and cryofixation, including freeze-fracturing [16], in TEM or SEM electron microscopy have been discussed in several publications [4, 7, 11, 14, 15, 20, 21, 261. Gelatin gels have been previously studied using various methods: chemical fixation [14,15] negative staining [22,24]; cryofixation [5,23,24], for example, but no decisive conclusion could be drawn on gelatin gel structure from these techniques.…”

“…Knowledge of the network organization and correlated properties of polymer gels is of great interest for biological and industrial purposes. Up to the present, few studies have dealt with three-dimensional (3-D) visualization of gel structure [16,25] and, in particular, physical gels such as gelatin.…”

The effect of binders on the rheological properties and the microstructure formation of lithium-ion battery anode slurries

“…The size of the structure is about a few hundred nanometer scale, and the network size is the same as in the anode slurry. In addition, there exists another evidence that the CMC molecules form the network structure [39]. So, it can be argued that the network structure in anode slurry at high concentration of CMC is originated from the CMC molecules.…”