Structure of polyamidoamide dendrimers up to limiting generations: A mesoscale description

Maiti, Prabal K and Li, Youyong and Cagin, Tahir and Goddard, William A (2009) Structure of polyamidoamide dendrimers up to limiting generations: A mesoscale description. In: Journal of Chemical Physics, 130 (14).

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Abstract

The polyamidoamide (PAMAM) class of dendrimers was one of the first dendrimers synthesized by Tomalia and co-workers at Dow. Since its discovery the PAMAMs have stimulated many discussions on the structure and dynamics of such hyperbranched polymers. Many questions remain open because the huge conformation disorder combined with very similar local symmetries have made it difficult to characterize experimentally at the atomistic level the structure and dynamics of PAMAM dendrimers. The higher generation dendrimers have also been difficult to characterize computationally because of the large size (294852 atoms for generation 11) and the huge number of conformations. To help provide a practical means of atomistic computational studies, we have developed an atomistically informed coarse-grained description for the PAMAM dendrimer. We find that a two-bead per monomer representation retains the accuracy of atomistic simulations for predicting size and conformational complexity, while reducing the degrees of freedom by tenfold. This mesoscale description has allowed us to study the structural properties of PAMAM dendrimer up to generation 11 for time scale of up to several nanoseconds. The gross properties such as the radius of gyration compare very well with those from full atomistic simulation and with available small angle x-ray experiment and small angle neutron scattering data. The radial monomer density shows very similar behavior with those obtained from the fully atomistic simulation. Our approach to deriving the coarse-grain model is general and straightforward to apply to other classes of dendrimers.

Item Type:	Journal Article
Publication:	Journal of Chemical Physics
Publisher:	American Institute of Physics
Additional Information:	Copyright of this article belongs to American Institute of Physics.
Keywords:	Monte Carlo methods; neutron diffraction; polymers; X-ray scattering
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	04 Jun 2010 10:22
Last Modified:	19 Sep 2010 05:56
URI:	http://eprints.iisc.ac.in/id/eprint/26182

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