Characterization of pore structure of polymer blended films used for controlled drug release
Journal article, 2016

The characterization of the pore structure in pharmaceutical coatings is crucial for understanding and controlling mass transport properties and function in controlled drug release. Since the drug release rate can be associated with the film permeability, the effect of the pore structure on the permeability is important to study. In this paper, a new approach for characterizing the pore structure in polymer blended films was developed based on an image processing procedure for given two-dimensional scanning electron microscopy images of film cross-sections. The focus was on different measures for characterizing the complexity of the shape of a pore. The pore characterization developed was applied to ethyl cellulose (EC) and hydroxypropyl cellulose (HPC) blended films, often used as pharmaceutical coatings, where HPC acts as the pore former. It was studied how two different HPC viscosity grades influence the pore structure and, hence, mass transport through the respective films. The film with higher HPC viscosity grade had been observed to be more permeable than the other in a previous study; however, experiments had failed to show a difference between their pore structures. By instead characterizing the pore structures using tools from image analysis, statistically significant differences in pore area fraction and pore shape were identified. More specifically, it was found that the more permeable film with higher HPC viscosity grade seemed to have more extended and complex pore shapes than the film with lower HPC viscosity grade. This result indicates a greater degree of connectivity in the film with higher permeability and statistically confirms hypotheses on permeability from related experimental studies.

pore shape

image processing


porous material scanning electron microscopy


Henrike Häbel

Chalmers, Mathematical Sciences, Mathematical Statistics

University of Gothenburg

SuMo Biomaterials

Helene Andersson

SuMo Biomaterials

Chalmers, Materials and Manufacturing Technology, Polymeric Materials and Composites

Anna Olsson

Chalmers, Physics, Eva Olsson Group

SuMo Biomaterials

Eva Olsson

SuMo Biomaterials

Chalmers, Physics, Eva Olsson Group

Anette Larsson

SuMo Biomaterials

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry

Aila Särkkä

SuMo Biomaterials

University of Gothenburg

Chalmers, Mathematical Sciences, Mathematical Statistics

Journal of Controlled Release

0168-3659 (ISSN)

Vol. 222 151-158

Subject Categories

Polymer Chemistry

Other Physics Topics

Probability Theory and Statistics

Areas of Advance

Materials Science





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4/5/2022 1