Crystallization-promoted emission enhancement of poly(L-lactide) containing a fluorescent salicylideneazine center with aggregation-enhanced emission properties

摘要: Fluorescent 1,2-bis(2,4-dihydroxybenzylidene)hydrazine (CN4OH) with aggregation-enhanced emission (AEE) properties was used as the initiator to induce ring-opening polymerization (ROP) of L-lactide, resulting in polymer CN-PLLA(n)s containing an AEE-active CN center. With both pairs p- and o-hydroxyl (OH) groups, CN4OH initiates ROP L-lactide solely p-OH groups are highly-emissive due rotational restriction imposed by remaining p-OHs central unit. A study on solid reveals that crystallization neighbouring PLLA chains, instead fluorescent center itself, determines AEE activity, e.g. crystalline is much higher intensity than amorphous CN-PLLA(n)s. As restricted molecular rotation main mechanism leading effective polylactide chains responsible for high CN-PLLA(n)s, contrast weak CN-PLLAs. The promotion designated crystallization-promoted enhancement (CPEE) focus study.