Fabrication of a multi-charge generable poly(phenyl isocyanide)-block-poly(3-hexylthiophene) rod–rod conjugated copolymer

Abstract

A facile construction of diverse polymeric nanostructures was reported by simple quaternization reaction and UV irradiation starting from the same rod–rod conjugated poly(4-isocyano-benzoic acid 5-(2-dimethylamino-ethoxy)-2-nitro-benzyl ester)-b-poly(3-hexylthiophene) (PPI(-DMAENBA)-b-P3HT) diblock copolymers, which were prepared by sequential living copolymerization of 4-isocyano-benzoic acid tert-butyl ester (PI) and 3-hexylthiophene (3HT) using Ni(dppp)Cl₂ as a catalyst in a one-pot process with a subsequent chemical modification. The facile quaternization reaction and UV irradiation upon PPI(-DMAENBA)-b-P3HT could afford quaternized PPI(-DMAENBA)-b-P3HT (PPI(-QDMAENBA)-b-P3HT) and poly(4-isocyano-benzoic acid)-b-poly(3-hexylthiophene) (PPI(-AA)-b-P3HT) copolymers. Two different polymeric micellar supramolecular structures with cationic and anionic surface properties could be obtained by direct dispersion of positively charged PPI(-QDMAENBA)-b-P3HT and negatively charged PPI(-AA)-b-P3HT copolymers into water. Interestingly, the resultant PPI(-QDMAENBA/DMAENBA)-b-P3HT block copolymers with a 40% degree of quaternization were found to exhibit unique light emissions with the color transformed from luminous yellow to pink depending on the solvent ratio of THF and water used. An almost neutral and ordered thin film was achieved on the exact stoichiometric charge balance between these two types of oppositely charged micelles, which highlights the potential to incorporate conjugated copolymers into the assembled block copolymer micelles (BCMs) to yield multifunctional ordered films and relevant applications.