Synthesis of Star Poly(N-isopropylacrylamide) with a Core of Cucurbit[6]uril via ATRP and Controlled Thermoresponsivity

A series of CB[6]-based macroinitiators with "n" bromo-initiation sites on the "equator" of CB[6] is developed for the synthesis of CB[6]-star poly(N-isopropylacrylamide) (CB[6]-star PNIPAM) by atom transfer radical polymerization. By taking advantage of the exceptional binding affinity of the CB[6] core, CB[6]-star PNIPAM is used as a host macromolecule to construct large compound vesicles in the presence of protonated n-butylamine at pH 5.63. The deprotonated n-butylamine is detached from the CB[6] core at pH 11.1, which destructs the vesicular structures. For CB[6]-star PNIPAM, the thermoresponsive properties can be adjusted by simply changing the formation and destruction of the inclusion complexes of the CB[6] core with n-butylamine. These results suggest that the prepared CB[6]-star PNIPAM shows pH and temperature responsiveness, which has great potential for the design of a dual response smart material.