Thermosome (THS), a group II chaperonin from the archaea Thermoplasma acidophilum, is described as nanoreactor for controlled/living radical polymerization. THS is a protein cage approx. 15.8 nm in size that displays two hemispheres with cavities of approx. 130 nm3 each (Figure A). The cavities of THS possess large pores that allow for macromolecules to enter and leave the reaction space.A copper catalyst was engineered into the cavities of the THS using bis-aryl hydrazone chemistry. The confined space of the nanoscale volume in the nanoreactor favorably influenced the atom transfer radical polymerization (ATRP) of N-isopropyl acrylamide and poly(ethylene glycol)methylether acrylate (Figure B). Reactions in the THS resulted in polymers with lower polydispersity indices in comparison to polymerizations that were catalyzed by globular protein-catalyst conjugates. This effect results most likely from a closer proximity of the reaction partners within the confined space of the protein nanoreactor.

Effect of the confined space within a protein nanoreactor on atom transfer radical polymerization

248th National Meeting (2014)

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