Morphology and crystallinity of the two diastereomer racemates of triglycidyl isocyanurate (TGIC)

Triglycidyl isocyanurate [2451-62-9] is a trifunctional monomer containing epoxy groups, and is presently used mainly for cross-linking carboxyl-functional polyester resins in powder coatings. There are three chiral carbon atoms in its molecule, and due to its symmetrical structure four antipodes exist according to the configuration of the chiral carbon atoms; namely RRR, SSS, RRS and SSR. Therefore the synthesized or commercially available TGIC is a physical mixture of two diastereomer racemates, i.e. beta-TGIC or RRR/SSS and alpha-TGIC or RRS/SSR. The physical and chemical properties of the two diastereomer racemates of TGIC are different. Their morphology and crystalline structure have been determined by polarizing microscopy and X-ray diffraction analysis. Beta-TGIC has hexagonal symmetry and belongs to the space group R3 or R3m. The cell parameters are: a0 = 14.037 Å, c0 = 11.55 Å, and cell volume: V0 = 1970.88 Å3. Alpha-TGIC has orthorhombic crystallinity and belongs to the space group Pna21. Its cell parameters are: a0 = 9.29 Å, b0 = 9.48 Å, c0 = 15.66 Å and cell volume: V0 = 1379.16 Å3.