Self-Assembly of a Tail-End Pyridinium Polyamphiphile Complexed with n-Alkyl Sulfonates of Variable Chain Length

Ionic-surfactants-based thermotropic liquid crystals

Ionic surfactants can be combined with various functional groups through electrostatic interaction, resulting in a series of thermotropic liquid crystals (TLCs).

Dipicolylamine Functionalized Polyfluorene Based Gel with Lower Critical Solution Temperature: Preparation, Characterization, and Application

A thermoresponsive fluorescent polymer gel with lower critical solution temperature (LCST) phase transition has been prepared by cooperating conjugated fluorene homopolymer poly(2,7-(9,9-di(8-di(2-picolyl)aminooctyl))fluorene) (PPAOF) and small organic dye sulforhodamine B (SRB) or its sodium salt (SRB-Na). The sol-gel phase transition originates from the electrostatic interactions between the protonated pyridyl/amino groups in PPAOF and the sulfonic groups in the organic dye molecules, as revealed by FTIR, variable-temperature ¹H NMR spectroscopies, and cyclic voltammetry measurements. Consequently, the LCST value can be finely controlled by simply tuning the component concentrations. Moreover, due to the inefficient energy transfer, the resulting fluorescent polymer gel exhibits two independent emission bands at 440 and 577 nm, assigned to the characteristic emissions from fluorene homopolymer and organic dye, respectively. Furthermore, this fluorescent polymer gel exhibits a reversible electrofluorochromic (EFC) property with high fluorescence contrast when it is assembled in a single-layer supporting electrolyte-free EFC device. Most interestingly, different fluorescence colors can be achieved from the two electrodes of the device. Our findings may present a new way to design conjugated polymer based LCST gels and EFC materials.