Size-controlled clustering of iron oxide nanoparticles within fluorescent nanogels using LCST-driven self-assembly.

Size-controlled clustering of iron oxide nanoparticles (IONPs) within the fluorescent polymer nanogels was achieved using the lower critical solution temperature (LCST) driven self-assembly and cross-linking of grafted polymer on the IONPs. The grafted polymer was comprised of oligoethyleneglycol methacrylate (OEGMA) and a novel dichloromaleimide functional methacrylate monomer as building blocks. As a result of the temperature responsive behavior of OEGMA, polymer grafted IONPs clustered to form larger nano-sized aggregates when heated above the LCST of the polymer. When these nano-sized aggregates were cross-linked using an amine-dichloromaleimide reaction, well-defined fluorescent hybrid nanogels could be fabricated. Moreover, the size of these hybrid nanogels was effectively controlled by varying the initial concentration of the polymer grafted IONPs in water.