Microfibres of conducting polythiophene and biodegradable poly(ester urea) for scaffolds

Hybrid scaffolds constituted of a mixture of conducting and biodegradable polymers are obtained by the electrospinning technique. Specifically, poly(3-thiophene methyl acetate) (P3TMA) and a copolymer derived from l -leucine, which bears ester, urea and amide groups (PEU- co -PEA), have been employed. Both polymers were selected because of their intrinsic properties and their high solubility in organic solvents. The biodegradable polymer renders continuous and homogeneous microfibers under most of the electrospinning conditions tested, appearing to be an ideal carrier for the polythiophene derivative. A spontaneous phase separation has been observed for concentrated solutions of PEU- co -PEA and P3TMA in chloroform-methanol mixtures. An enriched dense phase results on the conducting polymer and can be successfully electrospun, giving rise to scaffolds with up to 90 wt% of P3TMA. Morphological observations have indicated that continuous and regular microfibers are attained despite the high conducting polymer content. P3TMA presents a high doping level and leads to stable electrospun scaffolds by the simple addition of a low percentage of a high molecular weight carrier. The resulting scaffolds are practically amorphous and thermally stable, also presenting a pronounced electrochemical response and being electrochemically active. Thus, the formation of polarons and bipolarons at specific positions, the ability to exchange charge reversibly and the electrical stability of hybrid PEU- co -PEA/P3TMA electrospun scaffolds and P3TMA alone are practically the same. Electroactive scaffolds with up to 90 wt% of polythiophene are prepared by electrospinning using a poly(ester urea) carrier.