Dynamics of branched polymer molecules in dilute solution

1996 ◽  
Vol 34 (8) ◽  
pp. 1367-1390 ◽  
Author(s):  
Bruno H. Zimm ◽  
Ralph W. Kilb
1959 ◽  
Vol 37 (131) ◽  
pp. 19-42 ◽  
Author(s):  
Bruno H. Zimm ◽  
Ralph W. Kilb

1950 ◽  
Vol 5 (3) ◽  
pp. 383-386 ◽  
Author(s):  
Paul M. Doty ◽  
Robert F. Steiner

1947 ◽  
Vol 51 (1) ◽  
pp. 32-57 ◽  
Author(s):  
Paul Doty ◽  
Herman Wagner ◽  
Seymour Singer

An experimental investigation of the conditions necessary for the production of compact, single polymer molecules, in a form suitable for direct observation in the electron microscope, is described. Molecules are isolated by dispersing a dilute solution of the polymer as fine droplets on to a suitable substrate: ideally each droplet should contain either one or no polymer molecules. The solution is a mixture of two solvents, a good one and a poor one. Initially the good solvent predominates so that the probability of polymer aggregation is low. Preferential evaporation of the relatively volatile solvent on the substrate itself gives the poor solvent conditions needed for the formation of well-defined molecular spheres. Factors determining the choice of solvent, precipitant, and the composition of the mixture are discussed. There is little difficulty in obtaining single molecules with glassy amorphus polymers; rubbery polymers collapse and spherical molecules are formed only if the entire preparation is carried out at a temperature below that of the glass transition; crystalline polymers are not amenable to this technique. To obtain sufficient contrast the particles have to be shadowed and it is shown that, although certain dimensions are distorted by the metal coating, the shadow length faithfully represents the true particle diameter. Molecular weights, and their distribution, when of the order of a million and above, can readily be accurately determined. Conventional methods are unreliable in this region of high molecular weight.


The synthesis of intramolecularly crosslinked polystyrene molecules has bee nachieved by controlled chlormethylation of anionic polystyrene. The chlormethyl groups were reacted with n -butylamine and the secondary amine derivative thus produced was crosslinked by reaction with a diisocyanate in dilute solution. Samples were prepared containing a selected number of crosslinks in the range 5 to 150 per polymer molecule. The materials were completely soluble. The number of crosslinks in each sample was determined by quantitative infrared studies.


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