Murphy, Ryan P.Kelley, Elizabeth G.Rogers, Simon A.Sullivan, Millicent O.Epps, Thomas H. III2015-12-162015-12-16Copyright2014-10-14Unlocking Chain Exchange in Highly Amphiphilic Block Polymer Micellar Systems: Influence of Agitation. - ACS Macro Lett. (- 11):- 1106.2161-1653http://udspace.udel.edu/handle/19716/17325Publisher's PDFChain exchange between block polymer micelles in highly selective solvents, such as water, is well-known to be arrested under quiescent conditions, yet this work demonstrates that simple agitation methods can induce rapid chain exchange in these solvents. Aqueous solutions containing either pure poly(butadiene-b-ethylene oxide) or pure poly(butadiene-b-ethylene oxide-d4) micelles were combined and then subjected to agitation by vortex mixing, concentric cylinder Couette flow, or nitrogen gas sparging. Subsequently, the extent of chain exchange between micelles was quantified using small angle neutron scattering. Rapid vortex mixing induced chain exchange within minutes, as evidenced by a monotonic decrease in scattered intensity, whereas Couette flow and sparging did not lead to measurable chain exchange over the examined time scale of hours. The linear kinetics with respect to agitation time suggested a surface-limited exchange process at the air–water interface. These findings demonstrate the strong influence of processing conditions on block polymer solution assemblies.en-USACS AuthorChoice - This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.Articledoi:10.1021/mz500435d