Aqueous nanogels modified with cyclodextrin

In this work, the incorporation of reactive cyclodextrins (CDs) in aqueous nanogels based on poly(N-vinylcaprolactam) (VCL) is studied by surfactant-free precipitation polymerization process. alpha-, beta-, gamma-CDs were functionalized with acrylic groups and the average amount of vinyl bonds per CD molecule was adjusted to 2, 4, or 6. The increase of the CD concentration in the reaction mixture led to the reduction of the final hydrodynamic radius of nanogels from 227 nm to 62 nm. The increase of the vinyl groups number per CD molecule induced formation of smaller nanogels (R-h = 22.5 nm) and considerable increase of the crosslinking degree. Obtained cyclodextrin-modified nanogels show temperature sensitivity in aqueous medium with a volume transition point around 30 degrees C. The complexation properties of CDs incorporated in nanogel networks were proved by titration with phenolphthalein. (C) 2011 Elsevier Ltd. All rights reserved.