2-(Diethyl)aminoethyl Methacrylate as a CO₂-Switchable Comonomer for the Preparation of Readily Coagulated and Redispersed Polymer Latexes

CO 2 stimuli-responsive polystyrene latexes having a solids content of 27% were prepared in a surfactant-free emulsion polymerization (SFEP) under a CO 2 atmosphere, employing only commercially available chemical compounds: styrene, the initiator VA-061, and 0.54 mol % of the CO 2 -switchable comonomer DEAEMA. The resulting polymer particles are 230–300 nm in diameter and are monodisperse (PDI ≤ 0.054), as confirmed by DLS, TEM, and SEM. Although they are stable under a CO 2 atmosphere, the latexes can be easily destabilized by the bubbling of air through the sample at 40 °C, allowing for recovery of the particles by filtration. Recovered polymer particles can be dried to powder and readily redispersed in carbonated water, yielding latexes with very similar zeta-potential and particle size as the original latexes. In addition, the bicarbonate salt of poly(DEAEMA) formed during the polymerization has been found to act as a CO 2 -switchable flocculant, thus, facilitating the coagulation of the latex without altering the properties of the latex after redispersion.