Conformational effect on small angle neutron scattering behavior of interacting polyelectrolyte solutions: a perspective of integral equation theory.
We present small angle neutron scattering (SANS) measurements of deuterium oxide (D(2)O) solutions of linear and star sodium poly(styrene sulfonate) (NaPSS) as a function of polyelectrolyte concentration. Emphasis is on understanding the dependence of their SANS coherent scattering cross section I(Q) on the molecular architecture of single polyelectrolyte. The key finding is that for a given concentration, star polyelectrolytes exhibit more pronounced characteristic peaks in I(Q), and the position of the first peak occurs at a smaller Q compared to their linear counterparts. Based on a model of integral equation theory, we first compare the SANS experimental I(Q) of salt-free polyelectrolyte solutions with that predicted theoretically. Having seen their satisfactory qualitative agreement, the dependence of counterion association behavior on polyelectrolyte geometry and concentration is further explored. Our predictions reveal that the ionic environment of polyelectrolyte exhibits a strong dependence on polyelectrolyte geometry at lower polyelectrolyte concentration. However, when both linear and star polyelectrolytes exceed their overlap concentrations, the spatial distribution of counterion is found to be essentially insensitive to polyelectrolyte geometry due to the steric effect.
Department of Chemistry, College of Staten Island, City University of New York, Staten Island, New York 10314, USA.
Chwen-Yang
CY
Shew
Changwoo
C
Do
Kunlun
K
Hong
Yun
Y
Liu
Lionel
L
Porcar
Gregory S
GS
Smith
Wei-Ren
WR
Chen
D017666:Deuterium Oxide / Q000737:chemistry; D004573:Electrolytes / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D033363:Neutron Diffraction; D011108:Polymers / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry; D053838:Scattering, Small Angle; D012996:Solutions
D004573:Electrolytes; D011108:Polymers; D011137:Polystyrenes; D012996:Solutions; C003321:polystyrene sulfonic acid; D017666:Deuterium Oxide