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Poly(propylene imine) dendrimers as hydrogen donor in Type II photoinitiated free radical polymerization
Ist Teil von
European polymer journal, 2007-10, Vol.43 (10), p.4423-4430
Ort / Verlag
Oxford: Elsevier Ltd
Erscheinungsjahr
2007
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Three generations of poly(propylene imine) dendrimers, namely (PPI-16, PPI-32 and PPI-64; 16, 32 and 64 for generations 3, 4 and 5, respectively) were used as hydrogen donors in photoinitiated free radical polymerization of methyl methacrylate by using one of the following photosensitizers; benzophenone and thioxanthone. The effect of generation number of the dendrimer on photoinitiation efficiency and molecular weight of the resulting polymers was investigated. Glass transition temperatures and particle size measurements of the resulting polymers indicated the presence of nearly stretched polymer chains around the dendrimers. The location of hydrogen donating sites was evaluated by photolysis studies in the absence of monomer by using a stable radical namely, 2,2,6,6-tetramethylpiperidine-
N-oxyl free radical (TEMPO) and showed that hydrogen abstraction occurs from the inner tertiary amino groups. The TEMPO attached dendrimers were further used in the nitroxide mediated radical polymerization (NMP) of styrene to yield star polymers.