UiO-MOFs are based on zirconium cluster and carboxylic acid linkers. They have excellent 15 chemical and thermal stability, tolerance to linkers of different length and functionalities, 16 making them good candidates for a broad range of applications. However, difficulties of 17 processing the polycrystalline powder of MOFs limit their application. Here, we report for 18 the first time the synthesis of the UiO-66 in the presence of a well-defined poly 19 (methacrylic acid)-b-poly (methyl methacrylate) (PMAA-b-PMMA) nanoparticles (NPs) 20 prepared via Reversible Addition−Fragmentation Chain-transfer Polymerization 21 controlled Polymerization Induced Self-Assembly (RAFT-PISA). The PMAA-b-PMMA NPs 22 with multi carboxylic acid groups on their surface, well defined in shape and size, act as 23 multivalent connecting agent for the synthesis of the UiO-66. The resulting colloidally 24 stable UiO-polymer NPs are crystalline, porous, and with an improved processability as 25 was demonstrated by the preparation of a thin film nanocomposite (TFN) membrane. 26 This membrane was applied in the filtration of Nickel(II) phthalocyanine-tetrasulfonic 27 acid tetrasodium salt aqueous solution obtaining a water permeability circa 20 L m-2 h-1 28 bar-1 with a rejection of more than 90%. This unprecedented facile synthesis approach 29 could be universally applied to other MOFs, expanding their application in different fields 30 due to their enhanced processability.