Preparation of interconnected highly porous polymeric structures by a replication and freeze-drying process

Preparation of interconnected highly porous polymeric structures by a replication and freeze-drying process
Published Online: 17 Oct 2003
Received: 3 September 2002; Revised: 14 March 2003; Accepted: 23 April 2003
Qingpu Hou, Dirk W. Grijpma, Jan Feijen *
Journal of Biomedical Materials Research Part B: Applied Biomaterials
Volume 67B, Issue 2 , Pages 732 - 740
Wiley InterScience
Institute for Biomedical Technology (BMTI) and Department of Polymer Chemistry and Biomaterials, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands

email: Jan Feijen (j.feijen@utwente.nl)
*Correspondence to Jan Feijen, Institute for Biomedical Technology (BMTI) and Department of Polymer Chemistry and Biomaterials, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
Funded by:
European Community, Brite-Euram; Grant Number: BE 97-4612
Keywords
biodegradable polymers ? leachable template ? freeze-drying ? porous structures ? tissue engineering
Abstract
Three-dimensional degradable porous polymeric structures with high porosities (93-98%) and well-interconnected pore networks have been prepared by freeze-drying polymer solutions in the presence of a leachable template followed by leaching of the template. Templates of the pore network were prepared by fusing sugar or salt particles to form a well-connected structure. The interstices of the template were then filled with a polymer solution (5-15% w/v) in 1,4-dioxane, followed by freeze-drying of the solvent. Subsequent leaching of the sugar template ensures the connectivity of the pore network. The scaffold architecture consists of relatively large interconnected pores modeled after the template and smaller pores resulting from the freeze-drying process. The total porosity of the resultant porous structures is determined by the interstitial space of the leachable template and by the polymer concentration in the freeze-drying solution. The freezing temperature also has an effect on the final morphology of the porous structures. Compared with freeze-drying and combination of freeze-drying /particulate leaching techniques, this method facilitates higher interconnectivity of the scaffolds. Porous structures have been prepared from several relevant polymers in the biomedical and tissue-engineering field: poly(D,L-lactide) (PDLLA), 1000PEOT70PBT30, a segmented poly(ether ester) based on polyethylene oxide and polybutylene terephthalate, and poly(-caprolactone) (PCL). The mechanical properties of the porous structures prepared by this technique depend on the nature of the polymer, porosity, and the freezing temperature. With porosities in the range of 95-97%, the compression moduli of scaffolds prepared from the different polymers could be varied between 13.0 and 301.5 kPa. ? 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 67B: 732-740, 2003
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