The design and construction of high-efficiency nanoreactor systems have attracted a great deal of attention for their potential applications in materials science, biomedicine and catalysis. Especially, understanding the relationship between the precise internal structure of nanoreactors and their catalytic performance is essential for catalyst design. Here we report two bulky G2 dendronized norbornene macromonomers 8 and 13 containing nine hydrophilic triethylene glycol (TEG) termini with three and nine, respectively, 1,2,3-triazole (trz) rings, and their controlled polymerizations via the ring-opening metathesis polymerization (ROMP) technique using Grubbs' third-generation olefin metathesis catalyst. The self-assemblies of the obtained dendronized polymers (DPs) 9 and 14 in water then yield novel micellar nanoreactors with different location distribution of the coordinative intradendritic trz ligands. The recyclable nanoreactors are used to support Cu-I ion generated by in situ reduction of CuSO4 center dot 5H(2)O via sodium ascorbate, and strongly activate the Cu-I-catalyzed azide alkyne cycloaddition (CuAAC) "click" reactions in water, leading to exceptional TONs up to 250 000 and TOFs up to 16 670 h(-1). Remarkably, when the amount of Cu-I catalysts is less than 50 ppm, 9a-Cu-I exhibits considerably higher catalytic efficiency than 14a-Cu-I, which is attributed to the architectural difference of the two used DPs 9 and 14. This work highlights the role of the location of trz ligands in DPs nanoreactors on the catalytic efficiency of Cu-I catalyst, and the unique advantage of DP-type nanoreactors by less steric inhibition, compared to the congested dendrimers nanoreactors, and also rationalizes optimization in catalyst engineering. (C) 2018 Elsevier Ltd. All rights reserved.