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pH Dependent Elasticity of Polystyrene‐ block ‐poly(acrylic acid) Vesicle Shell Membranes by Atomic Force Microscopy
Author(s) -
Chen Qi,
Vancso G. Julius
Publication year - 2011
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201100332
Subject(s) - membrane , polystyrene , atomic force microscopy , elasticity (physics) , acrylic acid , materials science , composite material , vesicle , polymer chemistry , microscopy , chemical engineering , polymer science , chemistry , copolymer , nanotechnology , polymer , optics , physics , biochemistry , engineering
We assess the elastic properties of PS‐ b ‐PAA vesicle membranes under different pH values by AFM force measurements. We find that based on the shell deformation theory, the values of the estimated apparent Young's modulus of the vesicle membranes decrease as the pH of the solution increases. The onset of the decrease of E coincides with the surface p K a determined from ζ‐potential measurements. This decrease of E at higher pH is attributed to electrostatic repulsion between the deprotonated PAA chains resulting in the thinning of the vesicle membrane.