Strong and Facile Adhesives Based on Phase Transitional Poly(acrylic acid)/Poly(ethylenimine) Complexes

Polyelectrolyte complexes have demonstrated their potential application as adhesives to several substrates. However, it is unfortunate that the in-depth study focusing on polyelectrolyte phases as well as rheological analysis is insufficient to uncover the origin of the adhesive properties. Here, we precisely investigated the factors of polyelectrolyte adhesives in terms of electrostatic interaction using conventional rod coating and pH-induced phase transition, followed by a phase study between poly(acrylic acid) and branched poly(ethylenimine). The phase was systemically controlled by parameters such as polymer ratio, concentration of NaCl, and pH level. Then, the rheological modulus of each phase was studied to understand physical cross-linking. In relation to polyelectrolyte adhesives, it was found that a higher viscous phase led to more intensive adhesion strength. In addition, ther…