Document Detail


The Viscosity of Solutions of Poly(propylene imine) Dendrimers in Methanol.
MedLine Citation:
PMID:  11237446     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The viscosity of solutions of poly(propylene imine) dendrimers in methanol has been determined. An Ubbelohde and a low-shear rotational viscometer have been used. The viscosity was Newtonian for every concentration and shear rate used. The value of the Huggins coefficient indicates soft sphere behavior. The viscosity of the lower generations as a function of the volume fraction can be described with a single exponent, where the exponent is comparable to the intrinsic viscosity. The viscosity of the 4th and 5th generation dendrimers shows a stronger increase from a volume fraction of about 0.15 to 0.30. This increase is much smaller than that expected, using the Krieger-Dougherty formula for hard spheres with the hydrodynamic radius determined from the intrinsic viscosity. This smaller increase and the small value of the Huggins coefficient are interpreted in terms of a breakdown of the solvation layer. At a volume fraction of 0.3 the dendrimers, using the radius of gyration as the radius, start to touch each other. From the dependence of the viscosity on the concentration and the dependence of the viscosity on the molar weight, it can be concluded that dendrimers do not interpenetrate. It is concluded that they deform (collapse). Copyright 2001 Academic Press.
Authors:
Ivo B. Rietveld; Dick Bedeaux
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Publication Detail:
Type:  JOURNAL ARTICLE    
Journal Detail:
Title:  Journal of colloid and interface science     Volume:  235     ISSN:  1095-7103     ISO Abbreviation:  J Colloid Interface Sci     Publication Date:  2001 Mar 
Date Detail:
Created Date:  2001-Mar-9     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0043125     Medline TA:  J Colloid Interface Sci     Country:  -    
Other Details:
Languages:  ENG     Pagination:  89-92     Citation Subset:  -    
Affiliation:
Colloid and Interface Science Group, Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, Leiden, 2300 RA, The Netherlands
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