Multistimuli responsive ternary polyampholytes: Formation and crosslinking of coacervates

A series of multiresponsive ternary polyampholytes were prepared by free‐radical copolymerization of N‐(3‐aminopropyl) methacrylamide hydrochloride (APM), methacrylic acid (MAA), and N‐(2‐hydroxyethyl) acrylamide (HEA). APM and MAA were held at 1:1 molar ratio, while the HEA monomer feed was varied between 14 and 33 mol %. Compositional drift during polymerization was monitored by ¹H nuclear magnetic resonance, and minimized by adjusting the reactivity of MAA through its degree of ionization. The resulting polyampholytes phase‐separate from aqueous solution to form coacervate droplets, depending on HEA content, pH, ionic strength, and temperature. These coacervate droplets could be covalently crosslinked and the resulting hydrogel particles were found to swell with increasing ionic strength. Such soluble and microgel polyampholytes open opportunities for new multistimuli responsive biomaterials. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2109–2118