Enhancing the emission of hexa-peri-hexabenzocoronene-containing polynorbornene via electron donating, unsymmetric constitution and solvent effects

Abstract

The organo-soluble and extremely stable polynorbornene PHNB-HPB with a hexaphenylbenzene (HPB) moiety was prepared by ring-opening metathesis polymerization (ROMP) followed by hydrogenation. The hexa-peri-hexabenzocoronene (HBC)-containing PHNB-HBC, which is insoluble in commercial organic solvents, was prepared by the cyclodehydrogenation of PHNB-HPB. The glass transition temperature of PHNB-HPB was 205 °C. The temperatures required for a 10% weight loss (T_d10) for PHNB-HPB and PHNB-HBC were 428 °C and 456 °C under a nitrogen flow, respectively. The PHNB-HBC exhibited an ordered self-assembly in the solid state. The exfoliation of PHNB-HBC aggregates was tested by ultrasonication in various solvents. The PHNB-HBC dispersion solutions showed an intensive emission of the 0–0 transition (465 nm) due to the lower D_6h symmetrical structure and alkoxy substituents. Between different solvents, the dispersion in N-cyclohexyl-2-pyrrolidone (CHP) showed the highest individual metric and the strongest 0–0 transition (465 nm), indicating higher dispersibility.