Dynamics of Semiflexible Dendrimers in Dilute Solutions

Abstract

The dilute solution dynamic properties of dendrimers are theoretically studied in the framework of an optimized Rouse−Zimm approach. Semiflexibility is implemented by modeling topological restrictions on the directions and orientations of the respective bond vectors. This accounts for the neglect of excluded volume interactions in the limit of short spacers. The transport properties, particularly, the behavior of intrinsic viscosity and translational diffusion coefficient are analyzed as functions of flexibility and dendrimer generational growth. The intrinsic viscosity reveals a characteristic maxima, as is experimentally observed in some cases. The value and position of the maxima varies with the topology of the molecule and is mainly dictated by the longest relaxation times. The diffusion coefficient shows a steady decrease for all topologically different conformations up to the fourth generation. The inclusion of hydrodynamic interactions accelerates the dynamics of all semiflexible dendrimer models by decreasing the respective range of intrinsic viscosity and diffusion coefficient values. The structural differences between the different conformations are manifest in the subsequent generations. These topologically dependent flexibility parameters provide suitable approximations to explore the intramolecular dynamics of real dendrimers.

Analytical model for the dynamics of semiflexible dendritic polymers

“…The situation described by the GGS is certainly not that of dendrimers in the narrow sense, whose monomers are connected by quite stiff, covalent bonds, with relatively well-defined orientations. To realistically describe such objects one has to put up with strong local restrictions, [19][20][21] and such semiflexible schemes [22][23][24][25] as considered here cannot do them full justice. Our semiflexible scheme is better justified in treating dendritic polymers with linear spacers between their branching points, such as given in Ref.…”

Conformation and intramolecular relaxation dynamics of semiflexible randomly hyperbranched polymers

“…Semiflexibility is accounted by introducing bond correlations, which is implemented as restrictions on the direction and orientation of the constituent bond vectors. These restrictions are modeled through an appropriate choice of normalized spherical harmonics Y m l (θ, φ), used in our recent studies of the transport properties, 14 intramolecular relaxation 15 dynamics and various conformational properties 16,17 of dendrimers. This approximation accounts for the neglect of the excluded volume interactions, especially for short spacers.…”

Branched Semiflexible Polymers: Theoretical and Simulation Aspects

“…It is thus understandable that most recent works which study semiflexible branched polymers are connected to the discrete ORZ model. [35] Systems investigated in this way include star polymers, [41,42] dendrimers, [43][44][45] Cayley trees [43] and randomly branched polymers. [46] More recently, the ORZ model was used in determining the dynamics of proteins, [47] and its applications were reviewed in ref.…”