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Langmuir : the ACS journal of surfaces and colloids

Complexation of fluorescent tetraphenylthiophene-derived ammonium chloride to poly(N-isopropylacrylamide) with sulfonate terminal: aggregation-induced emission, critical micelle concentration, and lower critical solution temperature.


PMID 23075117

Abstract

Amphiphilic polymers with hydrophilic poly(N-isopropylacylamide) (PNIPAM) shell connecting hydrophobic tetraphenylthiophene (TP) core, which has the novel aggregation-induced emission (AIE) property, by ionic bonds were prepared to explore the AIE-operative emission responses toward critical micelle concentration (CMC) and lower critical solution temperature (LCST). To exercise the idea, ammonium-functionalized TP2NH(3)(+) and sulfonate-terminated PNIPAM were separately prepared and mixed in different molar ratios to yield three amphiphilic TP-PNIPAMn complexes for the evaluations of CMC and LCST by fluorescence responses. The nonemissive dilute aqueous solutions of TP-PNIPAMn became fluorescent when increasing concentrations above CMC. Heating micelles solution to temperatures above LCSTs causes further enhancement on the emission intensity. The fluorescence responses are explained by the extent of aggregation in the micelles and in the globules formed at room temperature and at high temperatures, respectively.