Dramatically shrinking of hydrogels controlled by pillar[5]arene-based synergetic effect of host-guest recognition and electrostatic effect

Polyacrylamide-based polymer networks were constructed as a hydrogel, and the novel and simple method was demonstrated to create dramatically shrinking hydrogels triggered by water-soluble pillar [5]arene (WP5)-based synergetic effect of host-guest recognition and electrostatic effect. The shrinking behavior of hydrogels was studied, which significantly exhibited an equilibrium shrinking percentage of approximately 89.2% in weight. More importantly, the WP5 controlled shrinking behavior of hydrogels was further investigated by the encapsulation and release of two types of small molecular drug models (anionic calcein and cationic rhodamine B), which displayed a much better selective release of anionic calcein than that of cationic rhodamine B, due to the host-guest interaction of WP5 and guest moiety of polymer networks in hydrogel as well as the electrostatic effect of anionic host molecule WP5. (C) 2017 Elsevier B.V. All rights reserved.