16. Functional Membranes with Molecular-Recognizable Properties

In this chapter, the design, fabrication, and performance of smart functional membranes with molecular-recognizable properties are introduced. The membranes are prepared by suspending β-cyclodextrin (CD) host molecules onto the freely mobile ends of thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) chains grafted in the membrane pores. By virtue of the interaction between the lower critical solution temperature (LCST) of PNIPAM chains and association constant of CD toward guest molecules, the membranes based on PNIPAM and CD are demonstrated to chiral separate enantiomers, adsorb/desorb guest molecules, and controlled-release model drug molecules. During the chiral separation, the PNG-ECD-grafted membranes separate D,L-tryptophan enantiomers with a high selectivity and regenerate with a high decomplexation ratio by simply changing the operation temperature. By simply adjusting the operation temperature, the membranes adsorb guest molecules at lower temperature and desorb at higher temperature. Moreover, the membranes with the same functional gate are featured with triple stimuli-responsive gating functions and release the model drug molecules in a controlled manner. The as-prepared membranes based on PNIPAM and CD are highly attractive for chiral separation, affinity separation, and controlled-release systems responding to the environmental temperature and guest molecules.