Coacervation between Two Positively Charged Poly(ionic liquid)s

Complex coacervates are usually formed through electrostatic attraction between oppositely charged polyelectrolytes, with a few exceptions such as coacervates of like-charge proteins and polyelectrolytes, both in vivo and in vitro. Understanding of the preparation and mechanisms of these coacervates is limited. Here, a positively charged poly(ionic liquid), poly(1-vinyl-3-benzylimidazolium chloride) (PILben), is designed that bears benzene rings in repeating units. Fluidic coacervates are prepared by mixing the PILben aqueous solution with a like-charge poly(ionic liquid) named poly(dimethyl diallyl ammonium chloride) (PDDA). The effects of polymer concentration, temperature, and ionic strength in the PILben-PDDA coacervate are studied. Raman spectroscopy and 2D H-1-C-13 heteronuclear single quantum coherence (H-1-C-13 HSQC) characterizations verify that the coacervate formation benefits from the cation-pi interaction between PILben and PDDA. This work provides principles and understandings of designing coacervates derived from like-charge poly(ionic liquids) with high charge density.