1. Effect of counterion valence on the pH responsiveness of polyamidoamine dendrimer structure.
- Author
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Yun Liu, Porcar, Lionel, Kunlun Hong, Chwen-Yang Shew, Xin Li, Liu, Emily, Butler, Paul D., Herwig, Kenneth W., Smith, Gregory S., and Wei-Ren Chen
- Subjects
DENDRIMERS ,STATISTICAL mechanics ,VALENCE fluctuations ,NANOSCIENCE ,RESEARCH methodology - Abstract
An accurate determination of the structure characteristics of protonated generation 5 polyamidoamine dendrimers in aqueous solution has been conducted by analyzing the small angle neutron scattering databased on a statistical mechanics model. In our investigation, the primary focus is to elucidate the effect of counterion valence on the counterion association and its impact on the intramolecular density profile within a dendrimer. In the range of our study for molecular protonation, a strong dependence of the structural properties of charged dendrimers on counterion valence is revealed. Our findings indicate that the association of a large amount of divalent counterions significantly reduces the effective charge of a dendrimer molecule. Surprisingly, no discernible transition of the density distribution profile is observed for the dendrimer charged by D
2 SO4 , as opposed to our previous observation of a pronounced transition in intramolecular density profile for the dendrimer charged by DCl. These findings may be understood from the thermodynamic processes of counterions. [ABSTRACT FROM AUTHOR]- Published
- 2010
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