Synthesis and Morphological Transformation of Conjugated Amphiphilic Diblock Copolymers in Mixed Solvents

Abstract

The synthesis, morphological transformation, and photophysical properties of a rod-coil block copolymer, poly[2,7-(9,9-dihexylfluorene)]-block-poly(2-vinylpyridine) (PF-b-P2VP), with P2VP coils of various lengths in a mixed methanol/tetrahydrofuran (MeOH/THF) solvent are reported. Various morphological structures of PF-b-P2VP aggregates, including spheres, short worm-like structures, long cylinders, and large compound micelles (LCMs), were observed after varying the coil length of PF-b-P2VP and the selectivity of mixed solvents. These aggregated structures demonstrated considerable variation with regard to optical absorption, fluorescence, and the PL quantum yield of rod-coil copolymers. The degree of hypsochromic spectral shift was enhanced as the length of P2VP coils and the content of poor solvent increased. This study reveals the influence of coil length and selectivity of solvents on the morphology and the optical characteristics of rod-coil amphiphilic copolymers.

Preparation and Characterization of Thermo-Responsive Rod-Coil Diblock Copolymers

“…The self-assembly of conjugated rod-coil block copolymers has been studied extensively towards novel structural, functional, and physical properties of supramolecular species [ 1 , 2 , 3 ]. The aggregation and microphase separation of such block copolymers driven by various novel functionalities of p–p interaction through solvent selection or rigid segmentation may result in various nanosized morphologies [ 4 , 5 , 6 ]. Different conjugated rod-coil block copolymers have been reported in the literature, including those of thiophene [ 7 , 8 ], phenylene [ 9 , 10 , 11 ], and quinolone [ 12 , 13 ].…”