Synthesis of Gold Nanorods Using Poly(vinylpyrrolidone) of Different Molecular Weights as an Additive

Abstract The use of poly(vinylpyrrolidone) (PVP) of different molecular weights (5‐360 kDa) during the synthesis of gold nanorods (AuNRs) via seedless and seed‐mediated approaches is reported. For both syntheses, the LSPR band can be tuned from 700 to 1050 nm by modifying the molecular weight of PVP in a time dependent addition of polymer. Moreover, the growth of AuNRs in 100 mM cetyltrimethylammonium bromide (CTAB) is accelerated as the molecular weight of PVP increases from 5 to 360 kDa for the seedless approach. In the case of AuNRs synthesized by the seed‐mediated approach, the aspect ratio decreases from 7.41 to 3.72 as the molecular weight of PVP increases to 55 kDa. For both protocols, high molecular weight of PVP reduces the shape yield despite of producing smaller AuNRs. Therefore, the incorporation of small amounts of PVP during the growth stage can be utilized for the preparation of anisotropic nanostructures to tune their optical properties and improve their shape yield.