Converse transitions between the micelles and the vesicles of pyrrolidone-based AIE amphiphilic copolymers in polar and apolar solvents.

ABSTRACT: Herein, a new family of aggregation-induced emission (AIE) amphiphilic copolymers, named poly(N-(2-methacryloyloxyethyl)pyrrolidone)-b-poly(lauryl methacrylate-co-1-ethenyl-4-(1,2,2-triphenylethenyl)benzene), PNMP _x -b-P(LMA _y -co-TPE _z ), was developed by the reversible addition-fragmentation chain transfer (RAFT) polymerization method. The polymerization degree x of the NMP segment was kept constant at 35, whereas that of the LMA segment ranged from 9 to 55 with the polymerization degree ratio y/z of the LMA and TPE segments being around 9. As a result, the PNMP _x -b-P(LMA _y -co-TPE _z ) copolymer gradually transformed from being water soluble to oil soluble with an increase in the length of the P(LMA _y -co-TPE _z ) segment. Moreover, these copolymers could form self-organized normal and reverse assemblies in both water and n-dodecane. Various morphologies, including spherical micelles, worm-like micelles and vesicles, were confirmed by the transmission electron microscopy (TEM) observation. Specifically, the micelle-to-vesicle transition via worm-like micelles occurred in the aqueous solution upon increasing the length of the P(LMA _y -co-TPE _z ) segment, whereas the reverse transition occurred in n-dodecane. Because of the presence of the AIE-active TPE segment, both the aqueous and the n-dodecane solutions of PNMP _x -b-P(LMA _y -co-TPE _z ) were highly luminescent, and their fluorescence quantum yields significantly depended on the polarity of the solvent and the morphology of the assemblies. Due to the strong luminescence properties of PNMP _x -b-P(LMA _y -co-TPE _z ) assemblies, these AIE-active amphiphilic copolymers acted as excellent bioimaging probes with high efficiency.

SUBMITTER: He X 

PROVIDER: S-EPMC9070998 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature