Insights into the Network Structure of Cross-Linked Polymers Synthesized via Miniemulsion Nitroxide-Mediated Radical Polymerization

The effect of reversible-deactivation radical polymerization on the structure of the network formed by copolymerization of mono- and divinyl monomers is studied. The nitroxide-mediated radical copolymerization (NMP) of butyl methacrylate and ethylene glycol dimethacrylate, initiated with the alkoxyamine 3-(((2-cyanopropan-2-yl)oxy)cyclohexylamino)-2,2-dimethyl-3-phenylpropanenitrile (Dispolreg 007) in an aqueous miniemulsion was used as a case study. Combination of asymmetric-flow field flow fractionation and small-angle X-ray scattering clearly showed that NMP led to a more homogeneous network structure formed by regions of relatively open networks connected with short polymer chain segments, whereas that of the polymer formed by free radical polymerization consists of densely cross-linked regions linked by long polymer chain portions.