Generalized concentration dependence of self-diffusion coefficients in poly(allylcarbosilane) dendrimer solutions

Self-diffusion of three high generations (the fifth, sixth, and seventh) of poly(allylcarbosilane) dendrimer in solutions with deuterated chloroform has been studied over a wide range of macromolecular concentrations (φ). Diffusivity has been measured by NMR with a pulsed gradient of the magnetic field. It is shown that concentration dependences of the dendrimer self-diffusion coefficients (D) can be reduced to the generalized concentration dependence. Over the range of volume concentrations from 0.01 up to 0.55, the curve of the generalized dependence of D for dendrimers coincides with the analogous dependence for globular protein in aqueous solutions. Analogous to the universal concentration dependence of D for linear polymers in solvent, the generalized concentration dependence of dendrimers tends to the asymptote D′(φ)/D0 ∞ φ0 = 1 in the limit of extremely dilute solutions and to the asymptote D(φ)/D0 ∞ φ-3 in the range of concentrated solutions 0.3 < φ < 0.55. Here, D0 - limφ-0 D(φ) and D(φ) are the self-diffusion coefficients of dendrimer in an extremely dilute solution and in a solution with macromolecular concentration φ, respectively. D′(φ) = D(φ)/L(φ), where L(φ) is a normalizing function, taking into account the change of the local mobility of dendritic branches as the macromolecular concentration increases; the L(φ) functions have been experimentally extracted from the concentration dependence of the longitudinal relaxation times for the dendrimers in solutions studied

Self-Diffusion and Nuclear Magnetic Relaxation of Dendritic Macromolecules in Solutions

The self-diffusion and nuclear magnetic relaxation of poly(butylcarbosilane) and poly(allylcarbosilane) dendrimers dissolved in deuterated chloroform 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(φ) obtained for macromolecules in the dendrimer-solvent 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 dendrimers 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. It is also shown that the experimental data obtained permit one to characterize the changes of the own monomer density of dendrimers depending on their molecular weight and, as a consequence, to make a conclusion about the swelling of dendritic macromolecules in the solutions studied

Generalized concentration dependence of self-diffusion coefficients in poly(allylcarbosilane) dendrimer solutions

Self-diffusion of three high generations (the fifth, sixth, and seventh) of poly(allylcarbosilane) dendrimer in solutions with deuterated chloroform has been studied over a wide range of macromolecular concentrations (φ). Diffusivity has been measured by NMR with a pulsed gradient of the magnetic field. It is shown that concentration dependences of the dendrimer self-diffusion coefficients (D) can be reduced to the generalized concentration dependence. Over the range of volume concentrations from 0.01 up to 0.55, the curve of the generalized dependence of D for dendrimers coincides with the analogous dependence for globular protein in aqueous solutions. Analogous to the universal concentration dependence of D for linear polymers in solvent, the generalized concentration dependence of dendrimers tends to the asymptote D′(φ)/D0 ∞ φ0 = 1 in the limit of extremely dilute solutions and to the asymptote D(φ)/D0 ∞ φ-3 in the range of concentrated solutions 0.3 < φ < 0.55. Here, D0 - limφ-0 D(φ) and D(φ) are the self-diffusion coefficients of dendrimer in an extremely dilute solution and in a solution with macromolecular concentration φ, respectively. D′(φ) = D(φ)/L(φ), where L(φ) is a normalizing function, taking into account the change of the local mobility of dendritic branches as the macromolecular concentration increases; the L(φ) functions have been experimentally extracted from the concentration dependence of the longitudinal relaxation times for the dendrimers in solutions studied

Generalized concentration dependence of self-diffusion coefficients in poly(allylcarbosilane) dendrimer solutions

Self-diffusion of three high generations (the fifth, sixth, and seventh) of poly(allylcarbosilane) dendrimer in solutions with deuterated chloroform has been studied over a wide range of macromolecular concentrations (φ). Diffusivity has been measured by NMR with a pulsed gradient of the magnetic field. It is shown that concentration dependences of the dendrimer self-diffusion coefficients (D) can be reduced to the generalized concentration dependence. Over the range of volume concentrations from 0.01 up to 0.55, the curve of the generalized dependence of D for dendrimers coincides with the analogous dependence for globular protein in aqueous solutions. Analogous to the universal concentration dependence of D for linear polymers in solvent, the generalized concentration dependence of dendrimers tends to the asymptote D′(φ)/D0 ∞ φ0 = 1 in the limit of extremely dilute solutions and to the asymptote D(φ)/D0 ∞ φ-3 in the range of concentrated solutions 0.3 < φ < 0.55. Here, D0 - limφ-0 D(φ) and D(φ) are the self-diffusion coefficients of dendrimer in an extremely dilute solution and in a solution with macromolecular concentration φ, respectively. D′(φ) = D(φ)/L(φ), where L(φ) is a normalizing function, taking into account the change of the local mobility of dendritic branches as the macromolecular concentration increases; the L(φ) functions have been experimentally extracted from the concentration dependence of the longitudinal relaxation times for the dendrimers in solutions studied

Generalized concentration dependence of self-diffusion coefficients in poly(allylcarbosilane) dendrimer solutions

Self-diffusion of three high generations (the fifth, sixth, and seventh) of poly(allylcarbosilane) dendrimer in solutions with deuterated chloroform has been studied over a wide range of macromolecular concentrations (φ). Diffusivity has been measured by NMR with a pulsed gradient of the magnetic field. It is shown that concentration dependences of the dendrimer self-diffusion coefficients (D) can be reduced to the generalized concentration dependence. Over the range of volume concentrations from 0.01 up to 0.55, the curve of the generalized dependence of D for dendrimers coincides with the analogous dependence for globular protein in aqueous solutions. Analogous to the universal concentration dependence of D for linear polymers in solvent, the generalized concentration dependence of dendrimers tends to the asymptote D′(φ)/D0 ∞ φ0 = 1 in the limit of extremely dilute solutions and to the asymptote D(φ)/D0 ∞ φ-3 in the range of concentrated solutions 0.3 < φ < 0.55. Here, D0 - limφ-0 D(φ) and D(φ) are the self-diffusion coefficients of dendrimer in an extremely dilute solution and in a solution with macromolecular concentration φ, respectively. D′(φ) = D(φ)/L(φ), where L(φ) is a normalizing function, taking into account the change of the local mobility of dendritic branches as the macromolecular concentration increases; the L(φ) functions have been experimentally extracted from the concentration dependence of the longitudinal relaxation times for the dendrimers in solutions studied

Self-Diffusion and Nuclear Magnetic Relaxation of Dendritic Macromolecules in Solutions

The self-diffusion and nuclear magnetic relaxation of poly(butylcarbosilane) and poly(allylcarbosilane) dendrimers dissolved in deuterated chloroform 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(φ) obtained for macromolecules in the dendrimer-solvent 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 dendrimers 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. It is also shown that the experimental data obtained permit one to characterize the changes of the own monomer density of dendrimers depending on their molecular weight and, as a consequence, to make a conclusion about the swelling of dendritic macromolecules in the solutions studied

Self-Diffusion and Nuclear Magnetic Relaxation of Dendritic Macromolecules in Solutions

The self-diffusion and nuclear magnetic relaxation of poly(butylcarbosilane) and poly(allylcarbosilane) dendrimers dissolved in deuterated chloroform 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(φ) obtained for macromolecules in the dendrimer-solvent 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 dendrimers 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. It is also shown that the experimental data obtained permit one to characterize the changes of the own monomer density of dendrimers depending on their molecular weight and, as a consequence, to make a conclusion about the swelling of dendritic macromolecules in the solutions studied

Self-Diffusion and Nuclear Magnetic Relaxation of Dendritic Macromolecules in Solutions

The self-diffusion and nuclear magnetic relaxation of poly(butylcarbosilane) and poly(allylcarbosilane) dendrimers dissolved in deuterated chloroform 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(φ) obtained for macromolecules in the dendrimer-solvent 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 dendrimers 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. It is also shown that the experimental data obtained permit one to characterize the changes of the own monomer density of dendrimers depending on their molecular weight and, as a consequence, to make a conclusion about the swelling of dendritic macromolecules in the solutions studied