ISSN:
0025-116X
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Molecular weigth distribution curves determined by electron microscopy exhibit a deviation when approaching a molecular weight of 106. Picturing of single molecules therefore was improved by the introduction of shadowing by electron beam. Techniques of preparation (by freeze-drying) and shadowing are described in detail. The scanning size of the electron beam shadowing is in between 15 and 20 Å and is given by the structure of the supporting film. By double shadowing from different sides it is demonstrated, that there is no “decoration effect” in electron beam shadowing. The lower limit of an exact determination of the dimensions is a molecular weight of ca. 105. It is shown with latex particles that there is a change of shape with time of the particles after sedimentation on the support which is dependent on the kind of polymer and of the conditions. Their volume though remains constant within the limits of error.
Additional Material:
13 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/macp.1977.021780416
