Research Unit of Sustainable Chemistry, University of Oulu, P.O. Box 4300, FI-90014 Oulu, Finland.
Fibre and Particle Engineering Research Unit, University of Oulu, P.O. Box 4300, FI-90014 Oulu, Finland.
ACS Macro Lett. 2023 Feb 21;12(2):147-151. doi: 10.1021/acsmacrolett.2c00743. Epub 2023 Jan 13.
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 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.
一种新型生物基单体 3,3'-联呋喃-5,5'-二羧酸制备的具有优异氧气阻隔性能的聚酯被报道。当暴露于空气中时，基于呋喃的聚酯会发生交联，其氧气透过率降低 2 个数量级，性能可与该类别的最佳聚合物（如乙烯-乙烯醇共聚物）相媲美。交联阻碍了无定形样品的结晶，也使它们不溶。这一过程可以通过紫外-可见测量来观察，在自由站立的薄膜中，在 320nm 和 520nm 之间的波长范围内，吸光度逐渐增加。导致这些变化的结构触发因素似乎很微妙：含有 5,5'-二取代 3,3'-联呋喃部分的聚酯发生交联，而含有 5,5'-二取代 2,2'-联呋喃部分的聚酯则无反应。基于 3,3'-联呋喃的聚酯实际上是一种半结晶热塑性塑料，一旦充分暴露于环境空气中，它就会缓慢转化为具有有趣材料性能的交联材料。
