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Title: Spatial distribution of intra-molecular water and polymeric components in polyelectrolyte dendrimers revealed by small angle scattering investigations

Abstract

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.

Authors:
 [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1];  [1];  [2];  [3]; ORCiD logo [1];  [1];  [1]; ORCiD logo [1]
  1. ORNL
  2. Rensselaer Polytechnic Institute (RPI)
  3. National Institute of Standards and Technology (NIST)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1037639
DOE Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
The Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 135; Journal Issue: 14; Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COHERENT SCATTERING; DISTRIBUTION; HYDRATION; NEUTRON DIFFRACTION; PH VALUE; POLYMERS; SMALL ANGLE SCATTERING; SOLVENTS; SPATIAL DISTRIBUTION; SYMMETRY; TUNING; WATER; WATER SUPPLY

Citation Formats

Chen, Chun-Yu, Chen, Wei-Ren, Herwig, Kenneth W., Hong, Kunlun, Li, Xin, Liu, Emily, Liu, Yun, Smith, Gregory Scott, Wu, Bin, Yang, Jun, and Do, Changwoo. Spatial distribution of intra-molecular water and polymeric components in polyelectrolyte dendrimers revealed by small angle scattering investigations. United States: N. p., 2011. Web. doi:10.1063/1.3651364.
Chen, Chun-Yu, Chen, Wei-Ren, Herwig, Kenneth W., Hong, Kunlun, Li, Xin, Liu, Emily, Liu, Yun, Smith, Gregory Scott, Wu, Bin, Yang, Jun, & Do, Changwoo. Spatial distribution of intra-molecular water and polymeric components in polyelectrolyte dendrimers revealed by small angle scattering investigations. United States. doi:10.1063/1.3651364.
Chen, Chun-Yu, Chen, Wei-Ren, Herwig, Kenneth W., Hong, Kunlun, Li, Xin, Liu, Emily, Liu, Yun, Smith, Gregory Scott, Wu, Bin, Yang, Jun, and Do, Changwoo. Sat . "Spatial distribution of intra-molecular water and polymeric components in polyelectrolyte dendrimers revealed by small angle scattering investigations". United States. doi:10.1063/1.3651364.
@article{osti_1037639,
title = {Spatial distribution of intra-molecular water and polymeric components in polyelectrolyte dendrimers revealed by small angle scattering investigations},
author = {Chen, Chun-Yu and Chen, Wei-Ren and Herwig, Kenneth W. and Hong, Kunlun and Li, Xin and Liu, Emily and Liu, Yun and Smith, Gregory Scott and Wu, Bin and Yang, Jun and Do, Changwoo},
abstractNote = {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.},
doi = {10.1063/1.3651364},
journal = {The Journal of Chemical Physics},
issn = {0021-9606},
number = 14,
volume = 135,
place = {United States},
year = {2011},
month = {10}
}