The Viscosity of Solutions of Poly(propylene imine) Dendrimers in Methanol

Rietveld, Ivo B.; Bedeaux, Dick

doi:10.1006/jcis.2000.7250

Cited by 19 publications

(14 citation statements)

References 17 publications

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“…We suspect that this result of the formation of a dense outside sphere (corona) with the increase of n . This effect was observed in the series of experimental works 19, 20, 39–46. Furthermore, authors assumed that the dendrimer possessed a dense corona 47–49.…”

Section: Part Iiia: Terminal Segments Modified By Massive Rigid Groupmentioning

confidence: 82%

Influence of Modified Terminal Segments on Dynamic Modulus and Viscosity of Dendrimer

Markelov

Lähderanta

Gotlib

2010

Macro Theory & Simulations

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Theoretical studies of the influence of modified terminal segments (TSs) on the relaxation spectrum of a dendrimer and dendrimer mechanical properties such as dynamic viscosity, η(ω), the elastic, G′(ω), and loss, G″(ω), moduli have been carried out by the Rouse model. Two major types of modified TS have been studied: (i) TS with an attached rigid massive group (i.e., TSs with additional friction) and (ii) TSs with a length different from the length of an inner segment. In the low‐frequency region, G′(ω), G″(ω), and η(ω) increase with the rise of friction of TS. In the high‐frequency region, dynamic moduli and viscosity depend on the length of TS. In the intermediate region, the moduli and viscosity are determined by a combined parameter: the characteristic time of TS, τend, which depends on the friction and length of TS. For both types of TSs, the position of the G″(ω) maximum, ωmax, depends on τend. In most of the considered cases, the linear dependence of ωmax on τend has been found. The method, which takes into account a deceleration of TS mobility with the rise in the number of generations, n, has been proposed. It was supposed that the effect of the deceleration corresponds to the forming of a dense surface shell with the rise of n, but similar behavior can also be caused by other reasons. In this case, ωmax shifts to the low‐frequency region with an increase in the number of generations. The conclusions of the theory developed in this paper are in agreement with results of the experiment, in which G′(ω) and G″(ω) were obtained for polyamidoamine dendrimers.magnified image

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Section: Part Iiia: Terminal Segments Modified By Massive Rigid Groupmentioning

confidence: 82%

Influence of Modified Terminal Segments on Dynamic Modulus and Viscosity of Dendrimer

Markelov

Lähderanta

Gotlib

2010

Macro Theory & Simulations

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“…These molecules are thought to have soft interiors and more densely packed outer layers, which do not allow interdendrimer penetration (18). Dendrimers differ from these suspensions in a number of ways.…”

Section: Discussionmentioning

confidence: 99%

“…Uppuluri et al concluded from this observation that adjacent dendrimers do not interpenetrate to form entanglements, even at high molecular weights (17). Furthermore, dendrimers in good solvents are Newtonian over a wide range of shear and have viscosities that increase with concentration approximately exponentially, or only slightly more than exponentially, over a wide range of molecular weight and concentration (15,17,18). Uppuluri et al concluded that this behavior is consistent with dendrimers having soft interiors and outer layers that are more densely packed and do not allow interdendrimer penetration (17).…”

Section: Introductionmentioning

confidence: 95%

“…In the melt, linear polymers show a step change in log viscosity η as a function of log molecular weight M. The step is thought to correspond to the onset of interchain entanglements, after which η ∼ M 3.4 (16). Dendrimers exhibit quite different behavior: they show a lower dependence of viscosity on molecular weight, with exponent 1.4 (polyamidoamine dendrimers in ethylenediamine) (17) and 2.1 (polypropyleneimine in methanol) (18). Uppuluri et al concluded from this observation that adjacent dendrimers do not interpenetrate to form entanglements, even at high molecular weights (17).…”

Section: Introductionmentioning

confidence: 99%

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Viscosity of Colloidal Suspensions in Aqueous Gelatin

Hone

Howe

2002

Journal of Colloid and Interface Science

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“…A linear dependence of scattering loss versus λ −4 was observed in a wide spectral range with the slope increasing for higher dendrimer concentrations, though some influence of background absorption was still evident. An increase of light scattering in dendrimer solutions of higher generations is well understood taking into account a corresponding increase of viscosity [15] and the phase behaviour in amine terminated dendrimer solutions [16].…”

Section: Resultsmentioning

confidence: 99%

UV spectral features of poly(propylene imine) dendrimers

Franckevičius¹,

Tamulienė²,

Babonas³

et al. 2011

Lith. J. Phys.

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The UV optical spectra of amine terminated poly(propylene-imine) (PPI) dendrimers of generations G1 to G5 were investigated experimentally. The occurrence of double band at 270-290 nm in absorption spectra of amine terminated dendrimer and the dependence of the spectra on the generation number and concentration in dichloromethane solution were discussed. The lineshape of double band was similar in the sequence G1 to G5, though some redistribution of the intensity of components was observed. A linear dependence of the absorbance in the double band was determined in the solutions at low concentrations of order 1·10−5 M. Experimental data have indicated that double band is caused by several optical transitions related to the core electronic excitations. A significant Rayleigh light scattering was found for higher dendrimer generations.

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The Viscosity of Solutions of Poly(propylene imine) Dendrimers in Methanol

Cited by 19 publications

References 17 publications

Influence of Modified Terminal Segments on Dynamic Modulus and Viscosity of Dendrimer

Influence of Modified Terminal Segments on Dynamic Modulus and Viscosity of Dendrimer

Viscosity of Colloidal Suspensions in Aqueous Gelatin

UV spectral features of poly(propylene imine) dendrimers

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