pH‐Sensitive Polymethacrylates as Potential Contrast Agents in ¹⁹F MRI

Abstract19F MRI is a promising method of diagnosis that can complement the commonly used 1H MRI with gadolinium contrast agents. Copolymers containing fluoroorganic groups demonstrate many advantages as potential 19F MRI contrast agents. In this work, a series of copolymers based on 2,2,2‐trifluoroethyl methacrylate (TFEMA), 1,1,1,3,3,3‐hexafluoroisopropyl methacrylate (HFiPMA), 2‐(dimethylamino)ethyl methacrylate (DMAEMA), or 2‐hydroxyethyl methacrylate (HEMA) units are prepared using atom transfer radical polymerization. The highest S/N values in a 19F NMR spectra is achieved with a copolymer containing 15–25 wt% TFEMA or 18–22 wt% HFiPMA. Copolymers of HFiPMA show a strong effect of pH on T1 and T2 relaxation times while only T2 is significantly affected for the TFEMA copolymers. DFT calculations reveal that the phenomenon is most likely caused by the pH‐induced changes in the distance of fluoroorganic groups within a polymer chain.