Hairy Hybrid Nanorattles of Platinum Nanoclusters with Dual-Responsive Polymer Shells for Confined Nanocatalysis

Abstract

Nanoparticles of transition metals, particularly noble metals, have been widely used in nanocatalysis. However, enhancing their stability and reusability during catalytic reactions has been a challenge that has limited the full use of the benefits associated with their miniature size. The encapsulation of noble metal nanocores as guest species into the hollow polymeric shells has emerged with the promise to solve this problem, which usually arises from a combined effect of the properties from their inorganic and polymeric components. In the present study, template-assisted synthesis of monodispersed hairy hybrid nanorattles, consisting of a movable platinum nanocluster and a hairy temperature- and pH-responsive polymer shell (Pt@air@P[MAA-co-(PMA-click-βCD-guest-PVCL)] HHNs; PMAA: poly(methacrylic acid); PPMA: poly(propargyl methacrylate); βCD: β-cyclodextrin; PVCL: poly(N-vinylcaprolactam)), was carried out and preformed as nanocatalyst. The novelty of this approach lies in the use of click chemistry and supramolecular assembly (referred to as “grafting to” approaches) to assist the creation of a protective and stimuli-responsive polymer shell to promote efficient mass transfer to encapsulated metal nanoparticles. The polymer shell not only acts as a physical barrier that prevents the coalescence of Pt nanocores but also provides a void space where organic transformation occurs on the surface of the ligand-free Pt nanocluster in a controlled manner. The as-synthesized HHNs were found to perform as a robust and reusable heterogeneous catalyst for catalytic reactions. One may find the present study a general and effective way for the synthesis of monodispersed hollow nanomaterials in a controllable and green manner.