Liquid sorbitol ether carbonate as intermediate for rigid and segmented non-isocyanate polyhydroxyurethane thermosets

Abstract

The facile chemical fixation of 18wt.% carbon dioxide by catalytic carbonation of sorbitol glycidyl ether, monitored by means of NMR and FTIR spectroscopy, affords sorbitol-based cyclic ether carbonate (SEC) as versatile intermediate for producing renewable non-isocyanate polyhydroxydroxyurethane (NIPU) materials. In sharp contrast to the solid, crystalline and highly insoluble pure sorbitol tricarbonate (STC), melting above 200°C close to its decomposition temperature, SEC is liquid at room temperature and fully miscible with a wide variety of polyfunctional amine curing agents. Despite high SEC carbonate functionality (4.2mol/kg), both gel time and pot-life time measurements confirm easy processing by curing SEC with polyfunctional aliphatic amines to produce new families of sorbitol-based NIPU materials. Particularly, blends combining flexible long-chain diamines such as dimer fatty acid based diamine (Priamine™ 1074) or polyether triamine (Jeffamine™ T403), respectively, with rigid short-chain diamines such as 1,6-hexamethylene diamine (HMDA), 1,12-dodecyl diamine (DDA), 2,2,4-trimethylhexamethylene diamine (TMHMDA) and isophorone diamine (IPDA), enable the simultaneous incorporation of soft and hard segments into NIPU networks. Moreover, miscible blends of SEC with STC remain liquid up to high STC content. Unparalleled by conventional bio-based NIPU chemistry, the curing of SEC or miscible SEC/STC blends, respectively, with IPDA yields sorbitol-based NIPU thermosets exhibiting significantly improved thermal and mechanical properties, as reflected by high glass transition temperatures surpassing 180°C and Young moduli exceeding 4000MPa.