TEMPERATURE SENSITIVITY OF A HYDROGEL NETWORK CONTAINING DIFFERENT LCST OLIGOMERS GRAFTED TO THE HYDROGEL BACKBONE

Hydrogels (HGs) containing two different lower critical solution tempe rature (LCST) oligomers grafted to the same HG backbone were synthesiz ed using macromonomers of the LCST oligomers. Cal boxy-terminated olig o(N-isopropylacrylamide) (oNIPAAm), oligo(N-vinylcaprolactam) (oVCL), and a random co-oligomer of NIPAAm and acrylamide (AAm) (o[NIPAAm-co-A Am]) were selected as the LCST oligomers. The macromonomers were synth esized by reaction of the terminal carboxy groups with glycidyl methac rylate. Using AAm as the base monomer for the HG, macromonomers of the carboxy-terminated oNIPAAm and oVCL were copolymerized with AAm and a cross-linker, and the HG was obtained. Despite the lack of temperatur e-sensitivity of the PAAm HG, the grafted HG showed two volume phase t ransitions corresponding to the LCSTs of the grafted side chains of oN IPAAm and oVCL. (C) 1998 Elsevier Science Ltd. All rights reserved.