Supramolecular self-assembly through inclusion complex formation between poly(ethylene oxide-b-N-isopropylacrylamide) block copolymer and alpha-cyclodextrin

Abstract

A well-defined poly(ethylene oxide-block-N-isopropylacrylamide) (PEO-b-PNIPAM) diblock copolymer was synthesized by atom transfer radical polymerization and formed the inclusion complexes (ICs) after selective threading of the PEO segment of the block copolymer through the cavities of alpha-cyclodextrin (alpha-CD) units. The formation of the alpha-CD/PEO ICs between alpha-CD and PEO segment of the PEO-b-PNIPAM transformed the system from its original random coil conformation into a rod/coil-like structure. The stacking of the alpha-CD/PEO ICs and phase separation within the alpha-CD/PEO-b-PNIPAM IC resulted in the self-assembly of long-range-ordered lamellar structure exhibiting alternating layers of (i) alpha-CD/PEO ICs with hexagonally packed plates and (ii) amorphous phase of unincluded PEO/PNIPAM with brush conformation. (C) 2009 Elsevier Ltd. All rights reserved.