Poly(N‐isopropylacrylamide‐co‐poly(ethylene glycol))‐acrylate simultaneously physically and chemically gelling polymer systems

Abstract

Abstract In an effort to create an in situ physically and chemically cross‐linked hydrogel for in vivo applications, N ‐isopropylacrylamide (NIPAAm) was copolymerized with poly(ethylene glycol)‐monoacrylate (PEG‐monoacrylate) and then the hydroxyl terminus of the PEG was further modified with acryloyl chloride to form poly(NIPAAm‐ co ‐PEG) with acrylate terminated pendant groups. In addition to physically gelling with temperature changes, when mixed with a multi‐thiol compound such as pentaerythritol tetrakis 3‐mercaptopropionate (QT) in phosphate buffer saline solution of pH 7.4, this polymer formed a chemical gel via a Michael‐type addition reaction. The chemical gelation time of the polymer was affected by mixing time; swelling of the copolymer solutions was temperature dependant. Because of its unique gelation properties, this material may be better suited for long‐term functional replacement applications than other thermo‐sensitive physical gels. Also, the PEG content of this material may render it more biocompatible than similar HEMA‐based precursors in previous simultaneous chemically and physically gelling materials. With its improved mechanical strength and biocompatibility, this material could potentially be applied as a thermally gelling injectable biomaterial for aneurysm or arteriovenous malformation (AVM) occlusion. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007