Microporous membranes staining

The second reactive inclusion method was developed [129] for microporous membranes. Stretched polypropylene, Celgard 2500 (trademark, Hoechst Celanese Corp.), shows little fine structure after ultrathin sectioning and examination in the TEM (Fig. 4.13A), although SEM study clearly reveals a surface pore structure. In order to enhance contrast, the membrane was treated with an unsaturated surfactant followed by osmium tetroxide staining and ultrathin sectioning. A 1-2% solution of polyoxyethylene allyl ether, Brij 97 (available from ICI Americas Inc.), in 50/50 methanol/water solution was used to... 

Fig. 4.13 TEM micrographs of a sectioned microporous membrane show little detail of the structure due to the low electron scattering of the polymer (A). Treatment with an unsaturated surfactant followed by osmium staining results in sections with enhanced contrast which permits assessment of the microporous structure (B).

A method using staining and ultramicrotomy (Section 4.4.2) has been demonstrated that shows the three dimensional structure of microporous membranes. such as Celgard 2500 membrane (trademark, Celanese Corp., New York [131]. Celgard is formed by film extrusion, annealing... 

Pechanek et al. (1982) determined ionic polysaccharides by fl migration through polyacrylamide and agarose gels and on cellulose acetate membranes the polyanions were detected by staining. At the dimensions found in gel micropores, pairs of surfaces create an adsorption potential ( ) 3.5 times that created at the same distance from a single surface (Void and Void, 1983). 

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