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

Maiti, Prabal K. and Li, Youyong and Çağin, Tahir and Goddard, William A., III (2009) Structure of polyamidoamide dendrimers up to limiting generations : a mesoscale description. Journal of Chemical Physics, 130 (14). Art. No. 144902. ISSN 0021-9606.

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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:Article
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URLURL TypeDescription
Çağin, Tahir0000-0002-3665-0932
Goddard, William A., III0000-0003-0097-5716
Additional Information:© 2009 American Institute of Physics. Received 21 November 2008; accepted 23 February 2009; published 8 April 2009. P.K.M. thanks DST, India for financial support. W.A.G. thanks NSF (CTS-0506951, CTS-0608889, CMMI-072870) for support.
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Department of Science and Technology (India)UNSPECIFIED
Subject Keywords:Monte Carlo methods; neutron diffraction; polymers; X-ray scattering
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Issue or Number:14
Record Number:CaltechAUTHORS:20090707-135227029
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14509
Deposited By: Tony Diaz
Deposited On:10 Jul 2009 22:09
Last Modified:03 Oct 2019 00:50

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