Macromolecular Nanotechnology Novel electrospun poly(e-caprolactone)-based bicomponent nanofibers possessing surface enriched in tertiary amino groups Dilyana Paneva a , Franc ßois Bougard b , Nevena Manolova a , Philippe Dubois b , Iliya Rashkov a, * a Laboratory of Bioactive Polymers, Institute of Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev 103A, 1113 Sofia, Bulgaria b Laboratory of Polymeric and Composite Materials, University of Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium Received 7 November 2007; received in revised form 28 December 2007; accepted 4 January 2008 Available online 15 January 2008 Abstract For the first time preparation of electrospun poly(e-caprolactone) (PCL) based nanofibers possessing surface enriched in tertiary amino groups is shown. For that purpose the pair PCL and poly(e-caprolactone)-b-poly[(2-dimethylamino)ethyl methacrylate] (PCL-b-PDMAEMA) diblock copolymers was used. PCL-b-PDMAEMA copolymers were synthesized using a combination of ring-opening polymerization and atom transfer radical polymerization (ATRP). Nanofibers with mean diameters ranging from 400 to 800 nm were obtained. Their morphology was evaluated by scanning electron (SEM) and atomic force microscopy (AFM). It was found that the morphology of the fibers depended on the weight ratio between the partners and the length of the PDMAEMA-block in the copolymers. The enrichment of the fiber surface in tertiary amino groups was studied by X-ray photoelectron spectroscopy (XPS). Increasing the copolymer content and the length of the PDMAEMA-block led to increase of the amount of tertiary amino groups on the fiber surface. The AFM analyses of the mechanical properties of the fiber surface showed that increasing the copolymer content led to decrease of the sur- face stiffness. The increase of the copolymer content led also to decrease of the melting temperature and the crystallinity degree in respect to PCL from the (co)polymer as determined by differential scanning calorimetry. Ó 2008 Elsevier Ltd. All rights reserved. Keywords: Block copolymers; Electrospinning; Nanocharacterization; Nanofibers; Poly(e-caprolactone) 1. Introduction The electrospinning is one of the most promising techniques for preparation of micro- and nanofibers of polyesters like poly(e-caprolactone) (PCL), poly- lactide and polyglycolide [1–3]. Such fibers gained significant interest due to the possibility to be used as scaffolds for cell and tissue engineering. PCL is approved as a biodegradable material compatible with soft and hard tissues, and it has found applica- tion for design of various devices used in the biomedical field [4]. During the last years special attention has been paid onto the preparation of fibers with specific surface chemistry [5,6]. The mod- ification of the surface of polyester materials is of special interest in terms of their biological behavior. 0014-3057/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.eurpolymj.2008.01.010 * Corresponding author. Tel.: +359 (0)2 9793468; fax: +359 (0)2 8700309. E-mail address: rashkov@polymer.bas.bg (I. Rashkov). Available online at www.sciencedirect.com European Polymer Journal 44 (2008) 566–578 www.elsevier.com/locate/europolj EUROPEAN POLYMER JOURNAL MACROMOLECULAR NANOTECHNOLOGY