Addressing the role of triphenylphosphine in copper catalyzed ATRP

Abstract

A new Atom Transfer Radical Polymerization (ATRP) process with triphenylphosphine (PPh₃) and [Cu^IIMe₆TREN]²⁺ as the catalyst system is reported. It is shown that PPh₃ can act not only as an efficient reducing agent (RA) but also as a supplemental activator (SA). The kinetics and mechanism of SARA ATRP of methyl acrylate (MA) in DMSO and DMSO/H₂O (90/10 v/v) were investigated in detail. The polymers presented controlled molecular weight, very low dispersity (Đ ≈ 1.03), and well-defined chain-end functionality. UV-Vis and electrochemical studies were performed to understand the role of PPh₃ and the Cu^IIBr₂/Me₆TREN complex in MA polymerization. It is demonstrated that the presence of PPh₃ does not affect the stability of the [BrCu^IIMe₆TREN]⁺ deactivator. The reported results reveal the high versatility of PPh₃ in ATRP, which, besides being commonly used in iron-mediated polymerizations, can also be employed as a SARA agent in copper-based ATRP systems.