Static and Dynamic Behavior in Model Dendrimer Melts:  Toward the Glass Transition

Abstract

Molecular dynamics (MD) simulations were employed in order to explore the static and dynamic response of model AB2 dendrimer melts of generations 3 and 4, in a temperature range covering the states of enhanced mobility, as well as the states where a significant dynamic slowdown led to a virtual freezing-in of the dendrimer motion. Particular emphasis was given to the investigation of the motional and conformational changes of the models in the proximity of a glasslike transition observed upon temperature decrease. The qualitative picture emerging from this study is consistent with recent pertinent experiments, offering thus the possibility for a better understanding of basic mechanisms responsible for the observed behavior.

Orientational mobility and relaxation spectra of dendrimers: Theory and computer simulation

“…At the same time their relaxation properties, which are very important for many practical applications, are poorly understood. [9][10][11][12][13] Computer simulation [14][15][16][17][18][19][20][21][22] is one of the perspective methods to study the dendrimer relaxation properties. Obtained simulation results correlate well with the existing experimental data on large-scale relaxation processes, such as diffusion 14 and intrinsic viscosity.…”

Local polymer dynamics under strong connectivity constraints: The dendrimer case

“…6,16,24 In this work we aim at a closer view on those mechanisms governing local polymer motion under a dense connectivity pattern and a well defined mobility contrast, by examining polymeric models bearing the dendritic topology. Dendrimers are glass-forming polymeric materials [25][26][27][28] with a quantitatively described level of dynamic heterogeneity well localized within their structure. [27][28][29][30][31] These attributes may essentially "filter out" certain dynamic features met either in liquids or linear polymers allowing a better assessment of the relative importance of each factor.…”

“…Dendrimers are glass-forming polymeric materials [25][26][27][28] with a quantitatively described level of dynamic heterogeneity well localized within their structure. [27][28][29][30][31] These attributes may essentially "filter out" certain dynamic features met either in liquids or linear polymers allowing a better assessment of the relative importance of each factor. For instance, in both of these glass-forming systems, regions of low or high mobility may fluctuate through the sample in a finite time scale, promoting specific mechanisms for cooperative particle rearrangements ͑e.g., stringlike particle/monomer clusters 9,22 ͒ that are expected to be suppressed in dendrimers.…”

Coarse-grained simulations of poly(propylene imine) dendrimers in solution

“…Still the interesting observation that interpenetration increases with decreasing temperature, and this dependence is greater for smaller dendrimers 34 , deserves further investigation.…”

“…Yet another method was applied on a melt of general bead-spring trifunctional core dendrimers under increasing temperatures 34 . There the interpenetration was calculated by looking at the average radial monomer density from the core bead, and where this graph overlaps with the average monomer density of other dendrimers this is counted as interpenetration.…”