Effect of Solvent Quality on the Solution Properties of Assemblies of Partially Fluorinated Amphiphilic Diblock Copolymers

Abstract

The effect of solvent on the formation of assemblies of partially fluorinated block copolymers in solution has been examined. Two classes of materials based respectively on 2,2,2-trifluoroethyl acrylate (TFEA) and 2,2,2-trifluoroethyl methacrylate (TFEMA) were dissolved in organic solvents, and the properties on successive addition of water were studied using NMR spectroscopy, NMR imaging, AFM, and TEM. The relatively high glass transition temperature of the methacrylate blocks resulted in the formation of kinetically trapped structures that could only be resolved following heating to temperatures well above the T g. The acrylate polymers formed loose assemblies in pure dimethylformamide, and on addition of water cylindrical micelles were observed. On the other hand, in pure acetone the partially fluorinated segments interacted more strongly with the solvent, with this structure inverting on addition of water. The NMR parameters were strongly dependent on the proposed structures in solution, and most markedly the mutual association of the fluorinated segments resulted in strong dipole–dipole interactions with the 19F spins. The importance of structure and solvent on the potential of these copolymers as MRI contrast agents is discussed, and broad design rules for effective 19F MRI agents are given.

Control through monomer placement of surface properties and morphology of fluoromethacrylate copolymers

“…Very few reports exist in the literature of the solubility parameters of fluorinated methacrylate polymers, apart from several studies using inverse gas chromatography by Papadopoulou and colleagues . In addition to that work, we have previously used the Van Krevelen group contribution method to calculate a solubility parameter ( δ 2 ) for PF1MA of 17.1 (MPa) 0.5 , in good agreement with the value obtained by extrapolating the data of Papadopoulou et al to room temperature. Using the same approach for the current system, we obtain a value of δ 2 for PF3MA equal to 16.7, close to the experimental value of 17.2.…”

Biodegradable core crosslinked star polymer nanoparticles as19F MRI contrast agents for selective imaging

“…Similar conclusions were reached by Peng et al in their study of the behaviour of linear block copolymers. 23,25 For CCS-2, the T 2 was much lower than that of CCS-1, but it showed a similar behaviour 15 with changes in pH. As before, the T 2 above pH 7 could not be measured, demonstrating the reduced mobility of the 19 F nuclei.…”

Fluorinated POSS‐Star Polymers for 19F MRI

“…Very recently, the development of polymeric agents for 19 F MRI has been an active research field. Owing to abundant architectures and functionalities present in polymeric systems, a wide range of partly fluorinated polymers have been developed as contrast agents (CAs) for 19 F MRI, including linear polymers, star polymers, hyperbranched polymers, and dendrimers . These studies have emphasized that successful 19 F MRI CAs should possess high fluorine content as well as highly mobile 19 F nuclei.…”