Synthesis and characterization of cross-linked water-dispersible conjugated polymer nanoparticles

Abstract

In this study, a novel synthetic method was demonstrated for the water-dispersible crosslinked light-emitting conjugated polymer nanoparticles with enhanced stability. In order to synthesize the novel conjugated polymer nanoparticles, thiophene-based monomers were synthesized with different functional groups such as bromine, hydroxyl and azide groups. These monomers were characterized by 1H-NMR spectroscopy. After the synthesis of the monomers, various polymers were synthesized via Suzuki coupling and oxidative polymerization. Their structural and optical properties were fully characterized by spectroscopic techniques such as 1H-NMR spectroscopy, FT-IR spectroscopy and Gel Permeation Chromatography (GPC). Finally, crosslinked conjugated polymer nanoparticles were synthesized by a diaminoalkyne crosslinker and various useful functional groups were introduced to the nanoparticles such as triazoles and amine groups. Incorporation of the hydrophilic functional groups to the conjugated polymer nanoparticles resulted with patchy, janus-like nanoparticles. CB6 was used as a catalyst for the first time in nanoparticle synthesis for 1,3-azide alkyne Huisgen cycloaddition which formed a conjugated polymer-based nanosized rotaxanes. Crosslinking of the conjugated polymer nanoparticles was also achieved by the irradiation of the nanoparticles under UV light in order to get shape-persistent nanoparticles. Various functional groups of the conjugated polymer nanoparticles make them highly versatile for biological studies such as cell imaging and drug delivery in biological systems. Synthesized nanoparticles were fully characterized by dynamic light scattering (DLS) measurement, transmission electron microscopy (TEM), FT-IR spectroscopy and UV-Vis spectroscopy.