An autonomous phase transition-complexation/decomplexation polymer system with a molecular recognition property

We describe a novel polymer that exhibits a coordination of molecular recognition and actuation functionalities within itself. This coordination induces an autonomous polymer shrinking/swelling phase transition, accompanied by the complexation/decomplexation of a guest molecule. The artificial polymer exhibited autonomous behavior induced by molecular recognition, which is a unique function of the living body. We used beta-cyclodextrin (CD) as the molecular recognition moiety, and poly(N-isopropylacrylamide) (NIPAM) as the actuation moiety in the polymer. Both these components affect each other: complexation between CD and its guest molecule 8-anilino1-naphthalenesulfonic acid ammonium salt (ANS) induces a phase transition in the NIPAM chain. Meanwhile, the phase transition in the NIPAM chain affects MANS complex formation. Coordination of these two phenomena induces an autonomous polymer shrinking/swelling behavior with CD/ANS complexation/decomplexation. We successfully observed this behavior using UV-vis and fluorescence spectroscopy.