Highly fluorinated polyimide blends - Insights into physico-chemical characterization

A thorough study on the physico-chemical properties of novel blends of fluorinated aromatic polyimides prepared on the basis of the similarity of dianhydride monomer units was performed. High-temperature solution polycondensation reactions resulted in high molecular weights polyimides further used as blend components. The blend films and coatings were rootedly characterized by various methods, including FTIR, DSC, thermal stability, UV-Vis and fluorescence spectroscopy, with emphasis on the miscibility behaviour. They exhibited high thermal stability and unique glass transition temperature, a critical evidence of the blends homogeneity. The presence of charge transfer interactions between neighbour polyimide chains was comprehended by UV-Vis and fluorescence spectroscopy, and discussed in correlation with chemical structures. The hydrophobic blend films showed a porous structure or an interlamellar or interfibrillar segregated morphology, good mechanical and optical properties with high transparency. Furthermore, new insights into their physico-chemical behaviour induced by the trifluoromethyl group or other structural features are discussed. (C) 2014 Elsevier Ltd. All rights reserved.