5-Ethylidene-2-norbornene (ENB) and 5-Vinyl-2-norbornene (VNB) based Alicyclic Polyols for the Synthesis of Polyesters

Amorphous polyesters derived from rigid alicyclic monomers with high glass transition temperatures are of great interest as potential substitute for poly(carbonate)s. Therefore, 5-ethylidene-2-norbornene (ENB) and 5-vinyl-2-norbornene (VNB) were identified as interesting diol monomer precursors to enhance the thermal properties of polyesters. The regioselective synthesis of the corresponding diols from ENB and VNB were optimized and first scale up experiments gave promising results for a potential large scale production of these polyester monomers. Moreover, for proof of concept, an alternative procedure was established to synthesize exclusively branched diols. Polymerization experiments were conducted with dimethyl terephthalate (DMT) as model compound to compare the polyesters with commonly used poly(ethylene terephthalate)s. Therefore, a series of polyesters were produced containing branched or linear or a mixture of both regioisomers, and structure property relationships were investigated with GPC, TGA and DSC analysis. The Tg values ranged from 75 to 103 °C, depending on the branched and linear moieties in the polyester microstructure and their molecular weights. Moreover, isosorbide (IS) was introduced as biobased comonomer, resulting in amorphous copolyesters with promising Tgs ranging from 81 to 97 °C.