Aminophosphine Based Lewis Pair for the Controlled Polymerization of Methyl Methacrylate

Abstract Lewis pair polymerization (LPP) has made significant progress in recent decades as a powerful method to synthesize polymers. The matching of electronic and steric properties of Lewis base/acid plays a decisive role in the activity, controlled behavior, and initiation efficiency (I*) of the polymerization. However, exploration of aminophosphine based Lewis base for polymer synthesis has been limited. Herein, commercially available aminophosphine, namely hexamethylphosphorous triamide (HMPT) in combination with common organoaluminum for the polymerization of methyl methacrylate (MMA), is presented. HMPT/iBu3Al shows controlled behavior in MMA polymerization with polymerization degree from 48 to 800, affording defined polymethyl methacrylate (PMMA) with molecular weight (Mn = 15.1–110.7 kg mol−1) with relatively narrow molecular weight distributions (Ð = 1.11–1.37). Matrix‐assisted laser desorption/ionization time of flight mass spectroscopy (MALDI‐TOF‐MS) affirmed the chain‐end fidelity of PMMA. The interaction mode between Lewis pair affects the in situ generated fraction of active species. The basicity and the cone angle of the aminophosphine determine the activity of the formed active species and I*. The successful application highlights the benefits of introducing P─N bonds into Lewis bases, thereby expanding the variety of Lewis base categories.