Surface Modification of Gold Nanorods by Grafting Fluorene-Based Conjugated Copolymers Containing Thiol-Pendants

Two conjugated surfactants of monomer TF and polymer PTF with pendant thiol groups are synthesized for surface modifications of gold nanorods (GNRs). Cetyltrimethylammonium bromide (CTAB)-GNRs (without surface-modification) in aqueous solutions are prepared, and the original CTAB surfactant is replaced with TF and PTF due to their thiol-gold grafting reactions. Surface-modified TF-GNRs and PTF-GNRs in THF are obtained. UV-visible spectra provide the grafting evidence of TF and PTF. Compared with TF-GNRs, the PTF-GNRs show better solubility and stability against aggregations of nanorods in THF. TEM and XPS confirm the existence of binding bonds between the sulfur groups of PTF and the gold surface in PTF-GNRs. Compared with polymer surfactant (PTF), the faster PL emission decay in PTF-GNRs match well with the PL quenching of PTF-GNRs. Surface modifications are verified by UV-visible, TEM, XPS, PL and lifetime measurements.