A zwitterionic “schizophrenic” copolymer with dual-responsiveness to temperature and carbon dioxide self-assembles to undergo a reversible phase transition in a weakly alkaline borate buffer solution. It can be switched “on” and “off” when sequentially treated with carbon dioxide/nitrogen (CO2/N2) due to the protonation–deprotonation of the tertiary amine groups along the polymer skeleton.
