Properties of polymers far from thermodynamic equilibrium

Polymers that are quenched during processing, for example in thin film formation, exhibit properties that vary from those of equilibrated materials.

Introduction

Polymer films are ubiquitous in our daily life. They are used in a large number of technological applications in the form of coatings, lubrication layers or mixing of small volumes of liquid (for example in micro- and nano-fluidics), all of great industrial interest.

Due to confinement, the properties of a thin film near the solid interface can be very different than that in the bulk. Furthermore film properties are believed to depend on the preparation of the thin film. Therefore, due to fabrication, thermal history and ageing time such films show significant changes in property and behaviour.

Thin polymer films

Aims of our project are to examine under which condition thin polymer films can be located in thermodynamic equilibrium and to find a description when they are not. It also includes the investigation of how entangled polymer chains do affect the process of equilibration regarding frustration or deceleration.

We want to develop a model which explains the non-equilibrium conformation of thin polymer melts and which predicts the consequences of thermodynamic non-equilibrium states in matters of behaviour and properties of the thin film.

Electro-hydrodynamic destabilisation (EHD)

The investigation of the conformations is done with Electro-hydrodynamic destabilisation and atomic force microscopy. Columnar patterns grow in liquid films upon application of an electric field. Wavelength and onset time of the instabilities indicate the stresses and the rheological properties of the polymer.

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