The influence of the molecular weight of the water-soluble polymer on phase-separated films for controlled release
Artikel i vetenskaplig tidskrift, 2016

Hydroxypropyl cellulose (HPC) and ethyl cellulose (EC) can be used for extended release coatings, where the water-soluble HPC may act as a pore former. The aim was to investigate the effect of the molecular weight of HPC on the microstructure and mass transport in phase-separated freestanding EC/HPC films with 30% w/w HPC. Four different HPC grades were used, with weight averaged molecular weights (Mw) of 30.0 (SSL), 55.0 (SL), 83.5 (L) and 365 (M) kg/mol. Results showed that the phase-separated structure changed from HPC-discontinuous to bicontinuous with increasing Mw of HPC. The film with the lowest Mw HPC (SSL) had unconnected oval-shaped HPC-rich domains, leaked almost no HPC and had the lowest water permeability. The remaining higher Mw films had connected complex-shaped pores, which resulted in higher permeabilities. The highest Mw film (M) had the smallest pores and very slow HPC leakage, which led to a slow increase in permeability. Films with grade L and SL released most of their HPC, yet the permeability of the L film was three times higher due to greater pore connectivity. It was concluded that the phase-separated microstructure, the level of pore percolation and the leakage rate of HPC will be affected by the choice of HPC Mw grade used in the film and this will in turn have strong impact on the film permeability.

Pellet formulation

Controlled release

Hydroxypropyl cellulose

Phase separation

Molecular weight

Film coating

Ethyl cellulose


Helene Andersson

Chalmers, Material- och tillverkningsteknik, Polymera material och kompositer

SuMo Biomaterials

Henrike Häbel

Chalmers, Matematiska vetenskaper, Matematisk statistik

Göteborgs universitet

SuMo Biomaterials

Anna Olsson

Chalmers, Fysik, Eva Olsson Group

SuMo Biomaterials

Sofie Sandhagen

Chalmers, Kemi och kemiteknik

Christian von Corswant

AstraZeneca AB

Johan Hjärtstam

AstraZeneca AB

Michael Persson

Chalmers, Kemi och kemiteknik

Mats Stading

Chalmers, Material- och tillverkningsteknik, Polymera material och kompositer

Anette Larsson

Chalmers, Kemi och kemiteknik, Tillämpad kemi

SuMo Biomaterials

International Journal of Pharmaceutics

0378-5173 (ISSN) 1873-3476 (eISSN)

Vol. 511 1 223-235


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