Eur. Phys. J. E 5, 13-20

Shrinking of ultrathin polyelectrolyte multilayer capsules upon annealing: A confocal laser scanning microscopy and scanning force microscopy study

S. Leporatti¹, C. Gao^{1, 2}, A. Voigt^{1, 3}, E. Donath¹ and H. Möhwald<sup>1

1</sup>  Max-Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
²  Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, P.R. China
³  Institute of Transfusion Medicine Medical Faculty Charité, Humboldt University of Berlin, 10098 Berlin, Germany

edwin.donath@mpikg-golm.mpg.de

(Received 20 January 2000 )

Abstract
Heating-induced morphological changes of micrometer size capsules prepared by step-wise deposition of oppositely charged polyelectrolytes onto melamine formaldehyde (MF) latex particles and biological cells with subsequent dissolution of the core have been investigated by confocal laser scanning microscopy (CLSM) and scanning force microscopy (SFM). For poly(styrenesulfonate-Na salt)/poly(allylamine hydrochloride) polyelectrolyte capsules a remarkable heating-induced shrinking is observed. An increase of the wall thickness corresponding to the capsule diameter decrease is found. The morphology of these microcapsules after temperature treatment is characterized. The thickening of the polyelectrolyte multilayer is interpreted in terms of a configurational entropy increase via polyanion-polycation bond rearrangement.

PACS
61.16.Ch - Scanning probe microscopy: scanning tunneling, atomic force, scanning optical, magnetic force, etc..
61.41.+e - Polymers, elastomers, and plastics.
68.60.Dv - Thermal stability; thermal effects.


© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2001