Communication Macromolecular Rapid Communications 1930 Macromol. Rapid Commun. 2011, 32, 1930−1934 © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim wileyonlinelibrary.com DOI: 10.1002/marc.201100489 1. Introduction Thermoresponsive polymers have gathered enormous attention over the past decade, as they are promising for a variety of uses, especially in the field of biomedical appli- cations. The most prominent polymer exhibiting ther- moresponsive behavior is poly( N-isopropylacrylamide) [P(NIPAM)]. [1] This is mainly due to its lower critical solu- tion temperature (LCST) of 32 °C, which is close to the body temperature and the stability of this value with respect to external influences such as pH or salt concentration. [2] Another class of materials exhibiting LCST behavior in aqueous solutions are polymers bearing oligo(ethylene glycol) side chains. [3] These macromonomer-based comb (co)polymers can either be synthesized by cationic polym- erization, as it has been presented by Aoshima and co-workers, [4] or by (controlled) radical polymerization techniques via the respective (meth)acrylates, that is, oligo (ethylene glycol) (meth)acrylate (OEG(M)A), studied intensively by Lutz. [5] These OEGMA-based materials are highly versatile because their LCST can be tailored by the incorporation of different comonomers [6] or end groups. [7] Another important aspect is their excellent biocompat- ibility, which is in line with their poly(ethylene glycol) (PEG)-based side chain structure. Besides these two prominent examples, only a few reports focus on linear poly(glycidyl ether)s, such as poly(glycidyl methyl ether), obtained by anionic polymerization, [8] with either block [9] or random structures. [10] In addition to these relatively simple systems, more sophisticated polyether-based The lower critical solution temperature (LCST) behavior of novel poly(ethylene glycol) (PEG)- based copolymers bearing multiple functional groups, obtained by anionic ring-opening (co) polymerization (AROP), has been investigated. Variable comonomer ratios of ethylene oxide (EO) and the corresponding oxiranes isopropyli- dene glyceryl glycidyl ether (IGG), ethoxyl vinyl glycidyl ether (EVGE), allyl glycidyl ether (AGE), or N, N-dibenzyl amino glycidyl (DBAG), particu- larly designed to implement functional groups at the PEG backbone, were found to influence the LCST behavior. Sharp transitions from trans- lucent to opaque solutions, comparable to other well-established stimuli-responsive polymers, were observed at temperatures ranging from 9 to 82 °C. The influence of the side group hydropho- bicity could be quantified by the comparison of the different copolymer systems observed. From an Epoxide Monomer Toolkit to Functional PEG Copolymers With Adjustable LCST Behavior Christine Mangold, Boris Obermeier, Frederik Wurm, Holger Frey* C. Mangold, Dr. B. Obermeier, Prof. H. Frey Institute of Organic Chemistry, Johannes Gutenberg-University, Duesbergweg 10-14, 55128 Mainz, Germany E-mail: hfrey@uni-mainz.de Dr. F. Wurm Ecole Polytechnique Fédérale de Lausanne (EPFL), Institut des Matériaux and Institut des Sciences et Ingenierie Chimiques, Laboratoire des Polymères, Batiment MXD, Station 12, 1015 Lausanne, Switzerland