Fluorine-19 (F-19)-based contrast agents are increasingly used for magnetic resonance imaging. Conjugated to polymers, they provide an excellent quantitative imaging tool to detect the movement of the polymeric nanoparticles in vivo as there is no background signal in tissue. One of the challenges is the decline in signal intensity when the conjugated hydrophobic fluorinated functionalities aggregate. Therefore, a new fluorinated monomer was prepared from l-arginine that carries a 2,2,2-trifluoroethyl functional group for imaging. The resulting monomer, 2,2,2-trifluoroethylamide l-arginine methacrylamide (3FArgMA), was copolymerized with poly(ethylene glycol) methyl ether methacrylate (PEGMEMA), [2-(2,3,4,6-tetra-O-acetyl-alpha-d-mannopyranosyloxy)ethyl methacrylate or 1-O-methacryloyl-2,3:4,5-di-O-isopropylidene-beta-d-fructopyranose, respectively, using poly(methyl methacrylate) macro-reversible addition-fragmentation chain transfer polymerization agent. The resulting block copolymers, which varied in 3FArgMA content, were self-assembled into micelles of hydrodynamic diameters from 25 to 60 nm. The permanently positively charged arginine functionality on the 3FArgMA displayed repulsive forces against aggregation enabling high spin-spin relaxation times (T-2) in acidic as well as alkaline solutions. However, the longer poly(ethylene glycol) side functionality in PEGMEMA enabled better steric stabilization (T(2 similar to)30 ms) while the short fructose side chain was not enough to maintain high T-2 values, in particular when a higher 3FArgMA content was used. (c) 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1994-2001