Biobased polyesters

摘要

Carbohydrates are an interesting source for biobased polymers. However, they contain a large number of functional groups, which can lead to excessive crosslinking. Although some linear polymers have been synthesised using carbohydrate-based monomers bearing free hydroxy groups, most have been undertaken with the excess hydroxyl groups protected. Those carbohydrate-based monomers containing a cyclic structure are preferred due to their superior polymer properties, eg their Tg and properties related to chain stiffness. Hence the interest in 2,5-furandicarboxylic acid as a possible replacement for terephthalic acid in aromatic polyesters. Isosorbide is the only carbohydrate-based bicyclic monomer industrially available today and again there is considerable interest in their use, but isosorbide and other less accessible dianhydrohexitols contain secondary hydroxyl groups with differing spatial positions that consequendy affects their reactivity. Another type of carbohydrate-based bicyclic monomer is the internal acetalised monomers, which have reactivity in the melt comparable to conventional acyclic monomers.