Novel electrospun poly(ε-caprolactone)-based bicomponent nanofibers possessing surface enriched in tertiary amino groups

For the first time preparation of electrospun poly(ε-caprolactone) (PCL) based nanofibers possessing surface enriched in tertiary amino groups is shown. For that purpose the pair PCL and poly(ε-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 surface 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.