Exploiting Confined Catalysts in Atom Transfer Radical Polymerization

Atom Transfer Radical Polymerization (ATRP) is a powerful method for obtaining highly controlled polymers through the concepts of living polymerization, established via an equilibrium between active radical species and dormant, halogen-capped species. This study aims to explore the application of a novel ligand for the metal catalyst, comprised of two identical tripodal tris(2-pyridilmethyl)amines linked together to form a chiral cage. The goal is to determine how this confined chiral nanospace influences the control and selectivity of ATRP, with the hypothesis that it will enhance selectivity due to the properties of confined spaces. The copper catalyst used operates in its (I) oxidation state for activation and in its (II) oxidation state for deactivation. Activation of the copper (II) catalyst was achieved via potentiostatic chronoamperometry. Voltammetric methods, primarily linear sweep and cyclic voltammetry, were utilized to analyse the behaviour of these complexes. Both analysis and polymerizations were conducted in a 5-necked, jacketed electrochemical cell maintained at 50°C under an inert atmosphere. Kinetic constants of the polymerization of butyl acrylates indicated that the kinetic activation of the halogen-capped, dormant growing chains decreased as the length of these molecules increased. Further studies on polystyrene initiators of different molecular weight showed that as the size of the initiator increased, the catalytic effect of the novel cage catalyst decreased drastically. These findings corroborate the initial hypothesis of dimensional selectivity of the catalytic complex, paving the way for further exploration of the unique possibilities offered by this kind of catalyst.