Palladium And Nickel Acetylide Complexes As Single-component Initiators For The Homo-and Co-polvmerization Of Polar Vinyl Monomers

By using a neutral palladium a-acetylide complex trans-bis(2-phenylethynyl)bis(triphenylphosphine)palladium [(Ph3P)2Pd(C=CPh)2, PPP] as a single-component catalyst, homopolymerization of 2-(dime-thylamino)ethyl methacrylate (DMAEMA) which has both amine and ester polar groups and its copolymrization with other polar monomers have been performed. Atom transfer radical' polymerization (ARTP) of methyl methacrylate (MMA) initiated by bis(2-phenylethynyl)bis- . (tributylphosphine)nickel [(Bu3P)2Ni(CsCPh)2, NBP] was also studied.1. Catalytic activities of different catalysts for DMAEMA were compared. The effects of solvent, catalyst concentration, monomer concentration, reaction time and reaction temperature on the polymerization of DMAEMA initiated by PPP were studied. PDMAEMA with high molecular weight (Mn=~300 000) and narrow molecular weight distribution (Mw/Mn=~2.0) was obtained. The best reaction conditions are: [M]=5mol/L , [M]/[Cat]=2500 , 60 , CHC13. Polymerization was immediately and completely terminated by a addition of radical scavenger, 2,2,6,6-Tetramethylpiperidinooxy (TEMPO), indicated that the polymerization proceeds via a radical mechanism. Further study shows that the polymerization has some living characteristic.2. By using PPP as a single-component catalyst, copolymerizations of DMAEMA with MMA, butyl methacrylate (BMA), methyl acrylate (MA) and butyl acrylate (BA), respectively, were studied. The reactivity ratio for each of them was determined by the Kelen-Tiidos method, they are: (1)rDMAEMA=1-13 rMMA=1.07; (2) rDMAEMA=0.77 , rBMA=0.84 ; (3) rDMAEMA=1.54 rMA=0.09; (4) rDMAEMA=0.71 rBA=0.14, respectively. The effects of .catalyst concentration, monomer concentration, reaction time and reaction temperature on the copolymerization of DMAEMA/MMA initiated by PPP were studied and found that molar ratios of the two monomers in the comonomer feed and resulting copolymer are very close. The present copolymerization is hindered completely by TEMPO and a radical mechanism is suggested.3. ATRP of MMA initiated NBP was also studied and narrow molecular weight distribution (Mu/Mn=~1.3) of PMMA was obtained. The effects of initiator, initiator concentration, catalyst concentration, monomer concentration and reaction time on the polymerization of MMA were studied.