Spatial distribution of intra-molecular water and polymeric components in polyelectrolyte dendrimers revealed by small angle scattering investigations
- ORNL
- Rensselaer Polytechnic Institute (RPI)
- National Institute of Standards and Technology (NIST)
An experimental scheme using contrast variation small angle neutron scattering technique (SANS), is developed to investigate the structural characteristics of amine-terminated poly(amidoamine) dendrimers (PAMAM) solutions. The focus is placed on understanding the dependence of intra-dendrimer water and polymer distribution on molecular protonation, which can be precisely adjusted by tuning the pH value of solution. Assuming the spherical symmetry in the spatial arrangement of the constituent component of dendrimer, and the atomic ratio of hydrogen-to-deuterium for the solvent residing within the cavities of dendrimer is identical to that for the solvent outside dendrimer, the intra-dendrimer water distribution along the radial direction can be determined based on the model of coherent scattering cross section developed in this work. Moreover, our result clearly reveals an outward relocation of the peripheral groups, as well as the enhanced intra-dendrimer hydration, upon increasing the molecular protonation and therefore allows the determination of segmental backfolding in a quantitative manner. The connection between these charge-induced structural changes and our recently observed progressively active segmental dynamics is also discussed.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1037639
- Journal Information:
- The Journal of Chemical Physics, Vol. 135, Issue 14; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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