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Accelerant‐promoted free radical polymerization of methacrylates by stabilized nitroxide unimolecular initiators: synthesis and characterization
Author(s) -
Ansong Omari E,
Jansen Susan,
Wei Yen,
Pomrink Gregory,
Li Shuxi,
Patel Alpa
Publication year - 2008
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.2414
Subject(s) - polymer chemistry , polymerization , radical polymerization , methacrylate , monomer , materials science , thermal stability , methyl methacrylate , dispersity , polymer , bulk polymerization , chemistry , organic chemistry
BACKGROUND: This investigation evaluates the effectiveness of initiator adducts for living and controlled polymerization of methacrylates, crosslinking of dimethacrylates and thermal stabilities of the resulting polymers. Adducts of 2,2,6,6‐tetramethyl‐1‐piperidinyloxy with benzoyl peroxide and with azobisisobutyronitrile were prepared and evaluated as stabilized unimolecular initiators for the free radical polymerization of methacrylate monomers using sulfuric acid as catalyst. The monomers used were methyl methacrylate, triethylene glycol dimethacrylate (TEGDMA) and ethoxylated bisphenol A dimethacrylate (EBPADMA). RESULTS: Successful polymerization was achieved at 70 and 130 °C with reaction times ranging from 45 min to 120 h. The dispersity ( D ) of poly(methyl methacrylate) (PMMA) was 1.09–1.28. The livingness and extent of control over polymerization were confirmed with plots of M n evolution as a function of monomer conversion and of the first‐order kinetics. The glass transition temperature ( T g ) for PMMA was 123–128 °C. The degradation temperature ( T d ) for PMMA was 350–410 °C. T d for poly(TEGMA) was 250–310 °C and for poly(EBPADMA) was 320–390 °C. CONCLUSION: The initiators are suitable for free radical living and controlled polymerization of methacrylates and dimethacrylates under mild thermal and acid‐catalyzed conditions, yielding medium to high molecular weight polymers with low dispersity, high crosslinking and good thermal stability. Copyright © 2008 Society of Chemical Industry