'Living'/controlled radical polymerization: From emulsion atom transfer radical polymerization to the synthesis of new nitroxides for stable free radical polymerization.

摘要

Emulsion polymerization is an important process for the industrial production of polymers. However, initial attempts at performing "living"/controlled radical polymerization under emulsion conditions were not particularly successful primarily due to latex instability. To address this problem a unique nanoprecipitation process was developed in our laboratory for the stable free radical polymerization (SFRP) process. The first part of this thesis describes attempts to generalize this process and extend it to the copper based atom transfer radical polymerization, ATRP, process. Details describing initial problems we had with reproducing some initial successful results are provided. Once the process was under control it was used to synthesize block copolymers. The ability of these block copolymers to self-assemble in aqueous solutions and in bulk were subsequently investigated and the results of these studies are detailed at the end of the discussion on the emulsion process.; The second part of the thesis deals with the SFRP process and more specifically with the difficulty of the process to moderate the polymerization of acrylates. Two reasons have been advanced to account for this difficulty; a high bond dissociation energy between the C-O bond linking the nitroxide moiety to the end of the polymer chain and an accumulation of excess nitroxide, caused by unavoidable chain termination, which causes inhibition of the polymerization. To address the high bond dissociation energy a nitroxide, specifically, 1,1'-diadamantyl nitroxide, containing very bulky substituents that might cause the bond to weaken, was synthesized and studied. To address the accumulation of excess free nitroxide, high temperature additives, that would slowly dissociate over time and consume the excess nitroxides, were studied. The results of both of these approaches are provided enabling some insight into what might be actually restricting the polymerization of acrylates.