BCMaterials Fortnightly Seminars #17

“Enhanced CT emission in Polyimides by Cyano-groups doping”  María San Sebastián (BCMaterials) Alternating different monomers, donor-acceptor conjugated polyimides (PI) are successfully synthesized by chemical imidization through in situ silylation of diamines. A detailed photophysical characterization is performed in the pure monomers and different polymers in tetrahydrofuran solutions. The emission spectra of the related donor-acceptor polymers with electron withdrawing cyano groups showed broaden and more intense fluorescence bands respect to the polymer without -CN groups. The new emission band is a consequence of the contribution of two different charge-transfer pathways: i) Intramolecular CT (ICT) state in the donor monomers due to the presence of strong electron withdrawing CN groups and ii) Intramolecular CT complex (CTC) in the PI polymer between the donor-acceptor monomers, which is red-shifted and shows longer lifetime respect to the ICT of the diamine monomers. The very wide emission band is a very interesting effect to obtain white light from UV light.   “How can we improve the scaffolds for tissue engineering?”  Eneko Axpe (UPV/EHU) Tissue engineering combines biology and materials science for developing functional substitutes of tissues and organs. One of the strategies, is to mimic the capacity of extracellular matrix (ECM) to guide and control tissues with a synthetic material. This application requires scaffolds that control nanoscale mechanical properties and mass transport to aid biological delivery and tissue regeneration. In this presentation we will analyse the state of the art of these materials and present a recent study in which we (i) measure the nanomechanical properties in chitosan-carbon nanotube nanocomposite scaffolds in close to physiological conditions and (ii) introduce a novel parameter (free-volume) in tissue engineering, in order to predict variations in transport properties.