Hyperbranched polymers meet colloid nanocrystals: a promising avenue to multifunctional, robust nanohybrids

Colloid nanocrystals (NCs) mainly include metal nanocrystals, semiconductor nanocrystals, and insulator nanocrystals, exhibiting interesting size-dependent electrical, optical, magnetic, and chemical properties that cannot be achieved by their bulk counterparts. However, there's a critical problem that NCs tend to aggregate, which induces degradation of their performance. Hyperbranched polymers (HPs) possess excellent attributes of three-dimensional topology, low viscosity, good solubility, and plenty of modifiable terminal groups. The combination of NCs and HPs to form nanohybrids cannot only endow NCs with multifunctionality, uniform dispersibility, and splendid solubility but also can impart extra properties to HPs. This article reviews the recent progress and state-of-the-art of the synthesis and applications of NCs-HPs nanohybrids (NHBs). NHBs can be obtained by three approaches: HPs first (i.e., NCs are formed with the stabilizer of HPs), NCs first (i.e., HPs are grafted on the surface of as-prepared NCs), and ligand exchange (the original ligand of NCs is replaced with HPs). Various HPs including hyperbranched poly(amidoamine), polyethylenimine, polyglycerol, polyester, polyamide, polyurethane, and poly(3-ethyl-3-hydroxymethyloxetane), as well as sorts of NCs such as metals (e.g., Ag, Au, Pd, Pt, and Rh), quantum dots (e.g., ZnO, CdS, CdTe, CdSe, and SnO₂), magnetic oxides (e.g., Fe₃O₄), rare earth compounds, and so forth, have been used to obtain NHBs. The NHBs can be applied in nanocatalysis, antimicrobia, biosensor, biological labeling, and other fields promising their bright future.