RAFT made methacrylate copolymers for reversible pH‐responsive nanoparticles

In this study, we designed and investigated pH-responsive nanoparticles based on different ratios of monomers with primary, secondary or tertiary amino groups. For this purpose, copolymers of methyl methacrylate (MMA) with different compositions of amino methacrylates (2-(dimethylamino)ethyl methacrylate (DMAEMA), 2-(tert-butylamino)ethyl methacrylate (tBAEMA) and 2-aminoethyl methacrylate hydrochloride (AEMA·HCI)) were synthesized using the reversible addition-fragmentation chain transfer (RAFT) polymerization process. The controlled nature of the radical polymerization was demonstrated by kinetic studies. All copolymers show low dispersities (ĐM < 1.2) with amino contents between 9 and 21 mol %. For the nanoparticle formation, nanoprecipitation with subsequent solvent evaporation was used. All suspensions were characterized by dynamic light scattering (DLS) and scanning electron microscopy (SEM). Different initial conditions of the formulations resulted in differently sized nanoparticles that have monomodal size distributions, relatively narrow polydispersity index (PDI) values and positive zeta potential values. The pH-stability test results demonstrated that, depending on the structure and amount of the amino content, the obtained nanoparticles reveal a reversible pH-response, such as dissolution at acidic pH values. The ability of the nanoparticles to encapsulate guest molecules was confirmed by pyrene fluorescence studies. The cytotoxicity assay results showed that the nanoparticles did not have any significant cytotoxic effect. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2711–2721