AbstractThe conditions for preparing poly‐N,N‐diethylacrylamide by group transfer polymerization (GTP) were investigated. While electrophiles did not catalyze the reaction, various nucleophilic substances could be used for that purpose. By using an appropriate initiator, either an ester or a carboxylic acid end group could be formed. The highest yields in the first case were obtained using tetrabutylammonium acetate and dimethylketene methyl trimethylsilyl acetal as catalyst and initiator, respectively, while the use of the corresponding bistrimethylsilyl compound as initiator gave polymers, albeit at lower yields, which carried the acidic end group. The1H‐NMR,13C‐NMR, and IR spectra of the polymers were taken and used together with information obtained with soft‐ionization mass spectrometric methods (MALDI‐MS, ESI‐MS, and FD‐MS) to elucidate molecule structure, apparent molecular weight distribution, polydispersity, and possible mechanisms of the termination reaction. The poly‐N,N‐diethylacrylamide prepared, showed an inverse temperature dependency in its water‐solubility, with a lower critical solution temperature between 29.8°C and 30°C. © 1