Precise Control of Molecular Weight Characteristics of Charge-Shifting Poly(2-(N,N-Dimethylamino)Ethylacrylate) Synthesized by Reversible Addition-Fragmentation Chain Transfer Polymerization.

Abstract

Poly(2-(N,N-dimethylamino)ethyl acrylate) (PDMAEA) is a promising charge-shifting polycation with the capacity to form a range of morphologically distinct polyelectrolyte assemblies. Nevertheless, the basic character of the monomer and its hydrolytic instability impedes its controlled synthesis to higher molecular weight (MW). Herein, the reversible addition-fragmentation chain transfer polymerization of DMAEA is reported using a tert-butanol/V70 initiator/trithiocarbonate-based chain transfer agent (CTA) polymerization setup. The CTA instability is demonstrated in the presence of the unprotonated tertiary amino group of the DMAEA monomer, which limits the control over the conversion and MW of the polymer. In contrast, the shielding of the amino groups by their protonation leads to polymerization with high conversions and excellent control over MWs of polymer up to 100000g mol-1. Hydrolytic degradation study at pH values ranging from 5 to 9 reveals that both basic and protonated PDMAEA undergo a pH-dependent hydrolysis. The proposed polymerization conditions provide a means of synthesizing PDMAEA with well-controlled characteristics, which are beneficial for controlling the complexation processes during the formation of various polyelectrolyte assemblies.