Novel Method for Visualizing Water Transport Through Phase-Separated Polymer Films
Journal article, 2014

Drug release from oral pharmaceutical formulations can be modified by applying a polymeric coating film with controlled mass transport properties. Interaction of the coating film with water may crucially influence its composition and permeability to both water and drug. Understanding this interaction between film microstructure, wetting, and mass transport is important for the development of new coatings. We present a novel method for controlled wetting of polymer coating films in an environmental scanning electron microscope, providing direct visual information about the processes occurring as the film goes from dry to wet. Free films made of phase-separated blends of water-insoluble ethyl cellulose (EC) and water-soluble hydroxypropyl cellulose (HPC) were used as a model system, and the blend ratio was varied to study the effect on the water transport properties. Local variations in water transport through the EC/HPC films were directly observed, enabling the immediate analysis of the structure-mass transport relationships. The leaching of HPC could be studied by evaporating water from the films in situ. Significant differences were observed between films of varying composition. The method provides a valuable complement to the current approach of making distinct diffusion and microscopy experiments for studying the dynamic interaction of polymer films with water.

hydroxypropyl cellulose

water transport

ethyl cellulose

environmental scanning electron microscopy

in situ


Anna Jansson

Chalmers, Applied Physics, Eva Olsson Group

SuMo Biomaterials

Catherine Boissier

AstraZeneca AB

M. Marucci

AstraZeneca AB

Mark Nicholas

AstraZeneca AB

Stefan Gustafsson

Chalmers, Applied Physics, Eva Olsson Group

SuMo Biomaterials

Anne-Marie Hermansson

SuMo Biomaterials

Chalmers, Chemical and Biological Engineering, Applied Surface Chemistry

Eva Olsson

Chalmers, Applied Physics, Eva Olsson Group

Microscopy and Microanalysis

1431-9276 (ISSN) 1435-8115 (eISSN)

Vol. 20 2 394-406

Subject Categories

Other Engineering and Technologies



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