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N,N-diethyl dithiocarbamato group induced photografting of methyl methacrylate onto polyurethane



The N,N-diethyl dithiocarbamato group present in a variety of compounds acts as an initiator in the photopolymerization processes. The photolability of this group is due to the cleavage of the C[BOND]S bond by UV irradiation. N,N-Diethyl dithiocarbamato-(1,2)-propane diol with a pendent N,N-diethyl dithiocarbamato group was prepared from 3-chloro-(1,2)-propane diol and sodium diethyl dithiocarbamate. A polyurethane macrophotoinitiator was then synthesized by a two-step process, where N,N-diethyl dithiocarbamato-(1,2)-propane diol was used as the chain extender. Other components used included 4,4′-diphenylmethane diisocyanate and poly(propylene glycol) (molecular weight = 1000). The polyurethane thus synthesized had pendent N,N-diethyl dithiocarbamato groups. This polyurethane macrophotoinitiator was then used to polymerize methyl methacrylate in a photochemical reactor (Compact-LP-MP 88) at 254 nm. The resulting graft copolymer, polyurethane-g-poly(methyl methacrylate), was freed from the homopolymer by a standard procedure. The graft copolymer was characterized by Fourier transform infrared spectroscopy, 1H-NMR spectroscopy, thermogravimetric analysis, differential scanning calorimetry, solution viscometry, and scanning electron microscopy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009