N-vinyleaprolactam-based microgels:: Effect of the concentration and type of cross-linker

New microgel particles produced by using N-vinylcaprolactam (VCL) and poly(ethylene glycol) diacrylate (PEGDA) or N,N'-methylenbisacrylamide (BA) were synthesized in a batch reactor. The influence of the concentration and type of crosslinker on polymerization kinetics and colloidal characteristics of such temperature-sensitive particles was studied. The partial and total conversion evolutions of VCL, PEGDA, and BA were determined by quantitative H-1 NMR and the average diameters of microgel particles together with the swelling-deswelling behavior were analyzed by means of photon correlation spectroscopy (PCS). Partial and total conversions, final average diameters at collapsed state, and the swelling-deswelling behavior varied as a function of the type of crosslinker. These results were attributed to the higher solubility and stabilizing ability of PEGDA compared with that of BA. (c) 2008 Wiley Periodicals, Inc.