The Association of Polymer Molecules in Dilute Solution.

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

Note on the distribution of polymer molecules in dilute solution

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

The direct observation of polymer molecules and determination of their molecular weight

1964 ◽  
Vol 279 (1376) ◽  
pp. 50-61 ◽  
Keyword(s):  
Molecular Weight ◽  
Direct Observation ◽  
Particle Diameter ◽  
Dilute Solution ◽  
Crystalline Polymers ◽  
Polymer Molecules ◽  
Molecular Weights ◽  
Preferential Evaporation ◽  
Poor Solvent

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.

On the dimensions of intramolecularly crosslinked polymer molecules I. The synthesis and chemical characterization of intramolecularly crosslinked polystyrene molecules having a narrow distribution of molecular weight

1973 ◽  
Vol 334 (1599) ◽  
pp. 453-463 ◽  
Keyword(s):  
Molecular Weight ◽  
Secondary Amine ◽  
Chemical Characterization ◽  
Polymer Molecule ◽  
Dilute Solution ◽  
Polymer Molecules ◽  
Crosslinked Polymer ◽  
Crosslinked Polystyrene ◽  
Infrared Studies

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.

Direct Observations of Polymer Molecules and Determination of their Molecular Weight

1966 ◽  
Vol 39 (3) ◽  
pp. 567-580
Author(s):  
M. J. Richardson
Keyword(s):  
Molecular Weight ◽  
Particle Diameter ◽  
Dilute Solution ◽  
Crystalline Polymers ◽  
Polymer Molecules ◽  
Molecular Weights ◽  
Direct Observations ◽  
Preferential Evaporation ◽  
Poor Solvent

Abstract 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 amorphous 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 water stability of natural clay aggregates containing polyvinyl alcohol

Soil Research ◽  
1968 ◽  
Vol 6 (1) ◽  
pp. 59 ◽  
Author(s):  
BG Williams ◽  
DJ Greenland ◽  
JP Quirk
Keyword(s):  
Polyvinyl Alcohol ◽  
Soil Aggregates ◽  
Equal Weight ◽  
Dilute Solution ◽  
Natural Clay ◽  
Clay Particles ◽  
Polymer Molecules ◽  
Loam Soil ◽  
Concentrated Solution ◽  
Clay Aggregates

The effect of the adsorption of polyvinyl alcohol (PVA) by natural clay aggregates on their ability to withstand rapid wetting and shaking in water has been determined. It was found for aggregates from the B horizon of the Urrbrae loam soil (60% of < 2 � material and 0.74% of organic carbon) that between 1 and 2% by weight of PVA was sufficient to almost completely prevent breakdown into micro-aggregates. Separation of clay particles from the aggregates by abrasive forces was also largely prevented. Polymer adsorbed slowly from a dilute solution was more effective than an equal weight of polymer adsorbed rapidly from a concentrated solution. Analysis of the rate of breakdown curves enabled the initial breakdown due to rapid wetting, and the subsequent abrasive forces, to be distinguished. The results provide further support for the hypothesis previously advanced that soil aggregates are stabilized by polymer molecules that line the surfaces of the pores, binding together the clay domains which comprise the walls of the larger pores.

Dynamics of branched polymer molecules in dilute solution

1959 ◽  
Vol 37 (131) ◽  
pp. 19-42 ◽  
Author(s):  
Bruno H. Zimm ◽  
Ralph W. Kilb
Keyword(s):  
Dilute Solution ◽  
Branched Polymer ◽  
Polymer Molecules
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