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Tuning Morphologies of Langmuir Polymer Films Through Controlled Relaxations of Non-Equilibrium States.
Chandran, Sivasurender; Dold, Stefanie; Buvignier, Amaury; Krannig, Kai-Steffen; Schlaad, Helmut; Reiter, Günter; Reiter, Renate.
Afiliação
  • Chandran S; †Institute of Physics, Albert Ludwigs Universität Freiburg, Freiburg 79085, Germany.
  • Dold S; †Institute of Physics, Albert Ludwigs Universität Freiburg, Freiburg 79085, Germany.
  • Buvignier A; ‡Ecole Nationale Superieure de Chimie de Rennes, 35708 Rennes Cedex 7, France.
  • Krannig KS; §Department of Colloid Chemistry, Max Planck Institute of Colloids and Interfaces, Potsdam D-14424, Germany.
  • Schlaad H; §Department of Colloid Chemistry, Max Planck Institute of Colloids and Interfaces, Potsdam D-14424, Germany.
  • Reiter G; ∥Institute of Chemistry, Universität Potsdam, Potsdam D-14476, Germany.
  • Reiter R; †Institute of Physics, Albert Ludwigs Universität Freiburg, Freiburg 79085, Germany.
Langmuir ; 31(23): 6426-35, 2015 Jun 16.
Article em En | MEDLINE | ID: mdl-26000718
ABSTRACT
Langmuir polymers films (LPFs) frequently form nonequilibrium states which are manifested in a decay of the surface pressure with time when the system is allowed to relax. Monitoring and manipulating the temporal evolution of these relaxations experimentally helps to shed light on the associated molecular reorganization processes. We present a systematic study based on different compression protocols and show how these reorganization processes impact the morphology of LPFs of poly(γ-benzyl-L-glutamate)(PBLG), visualized by means of atomic force microscopy. Upon continuous compression, a fibrillar morphology was formed with a surface decorated by squeezed-out islands. By contrast, stepwise compression promoted the formation of a fibrillar network with a bimodal distribution of fibril diameters, caused by merging of fibrils. Finally, isobaric compression induced in-plane compaction of the monolayer. We correlate these morphological observations with the kinetics of the corresponding relaxations, described best by a sum of two exponential functions with different time scales representing two molecular processes. We discuss the observed kinetics and the resulting morphologies in the context of nucleation and growth, characteristic for first-order phase transitions. Our results demonstrate that the preparation conditions of LPFs have tremendous impact on ordering of the molecules and hence various macroscopic properties of such films.

Texto completo: 1 Base de dados: MEDLINE Idioma: En Ano de publicação: 2015 Tipo de documento: Article

Texto completo: 1 Base de dados: MEDLINE Idioma: En Ano de publicação: 2015 Tipo de documento: Article