Self-diffusion and nuclear magnetic relaxation of dendritic macromolecules in solutions

Abstract

The self-diffusion and nuclear magnetic relaxation of poly(butylcarbosilane) and poly(allylcarbosilane) dendrimers disso[ved in deuterated chioroform and poly(amidoamine) dendrimers with hydroxyl surface groups in solutions with methanol have been studied. The diffusion rates (D) have been measured by the pulsed-field-gradient nuclear magnetic resonance. It is shown that experimental concentration dependences D((o) obtained for macromolecules in the dend¡ systems studied can be reduced to a unified view, and thus, the generalized concentration dependence of the normalized diffusion rates of dendrimers can be obtained. In the macromolecular volume concentration range from 0.01 up to 0.55, the generalized dependence of the normalized diffusion rates for dend¡ coincides with the analogous dependence for globular proteins in aqueous solutions; the last result suggests that self-diffusion features of dendrimers and globular proteins are in general similar. [t is also shown that the experimental data obtained permit one to characterize the changes of the own monoroer density of dendrimers depending on their molecular weight and, asa consequence, to make a conclusion about the swelling of dendritic macromolecules in the solutions studied.

Scaling Behaviour of PAMAM Dendrimers Determined by Diffusion NMR

“…With the obtained diffusion coefficients ( D ) the hydrodynamic radii ( R h ) have been calculated using the Stokes‐Einstein equation,22,23 where k B is the Boltzmann constant, T the temperature and η = 0.55 mPa is the viscosity of the solvent. This holds for dilute solutions, the concentration used here is in the dilute regime as has been shown before 24,25…”

Synthesis and study of the properties of the homologous series of polyallylcarbosilane dendrimers and their nonfunctional analogs

“…The properties of such samples have been stud ied previously by adiabatic calorimetry, 24,25 SAXS and SANS, 26 and NMR spectroscopy. 27 We measured the vis cosity of dendrimers in dilute solutions in toluene and the dendrimer density. The dependence of intrinsic viscosity on the generation number measured for the third to ninth …”

From the discovery of sodiumoxyorganoalkoxysilanes to the organosilicon dendrimers and back

“…The most important results turned out to be the data on dependence of characteristic Along with those obtained on capacity of dendrimer interior sphere, [24][25][26][27] the new results allowed us to characterize unambiguously carbosilane dendrimers as polymer objects not only according to formal features-presence of a great number of repeating units in molecular structure, but also to the ability to swell and shrink depending on a solvent quality. Figure 11 illustrates the operation done based on SANS contrast variation experiment results indicating the amount of solvent within hydrodynamic volume of carbosilane dendrimer.…”