Control of rapid phase transition induced by supramolecular complexation of β-cyclodextrin-conjugated poly(ε-lysine) with a specific guest

beta-Cyclodextrin-conjugated poly(is an element of-lysine) (beta-CDPL) was synthesized and used as a polymeric host for inclusion complexation with 3-trimethylsilylpropionic acid (TPA). The specific host-guest interaction was analyzed by electrospray ionization mass and X-ray diffraction spectroscopies. In this system, TPA included into the hydrophobic cyclodextrin cavity acted as a physical cross-linker by cooperative hydrophobic and ionic interactions, which gave an important role in viscosity or transmittance changes near physiological conditions. The pronounced effect of pH on the change of viscosity was supported by rheological data. On the other hand, reversible phase transitions of the supramolecular assembling system occurred very rapidly in response to minute changes of temperature, which was verified by UV-vis measurements. The delicate control of critical aggregation temperature was accomplished by changing the degree of substitution as well as varying molar feed ratio or solution concentrations across their upper critical solution temperature. This rapid and elaborate supramolecular assembling system is promising as smart materials and can find a broad range of applications.