High Oxygen Barrier Polyester from 3,3′-Bifuran-5,5′-dicarboxylic Acid
Tuomo P. Kainulainen, Tomi A. O. Parviainen, Juho Antti Sirviö, Liam McGeachie, Juha P. Heiskanen
Abstract
High Resolution Image Download MS PowerPoint Slide An exceptional oxygen barrier polyester prepared from a new biomass-derived monomer, 3,3′-bifuran-5,5′-dicarboxylic acid, is reported. When exposed to air, the furan-based polyester cross-links and gains O 2 permeability 2 orders of magnitude lower than initially, resulting in performance comparable to the best polymers in this class, such as ethylene-vinyl alcohol copolymers. The cross-links hinder the crystallization of amorphous samples, also rendering them insoluble. The process was observable via UV–vis measurements, which showed a gradual increase of absorbance between wavelengths of 320 and 520 nm in free-standing films. The structural trigger bringing about these changes appears subtle: the polyester containing 5,5′-disubstituted 3,3′-bifuran moieties cross-linked, whereas the polyester with 5,5′-disubstituted 2,2′-bifuran moieties was inert. The 3,3′-bifuran-based polyester is effectively a semicrystalline thermoplastic, which is slowly converted into a cross-linked material with intriguing material properties once sufficiently exposed to ambient air.