Application Of Amine Bisphenol Cobalt Metal Complexes And Tubular Magnesium Silicate In Polymerization And Copolymerization

Metal cobalt complexes were widely used in many fields such as materials and chemistry due to their excellent catalytic properties.At present,the use of free radical polymerization technology to prepare homopolymers and copolymers with narrow molecular weight distribution has became a hotspot in the field of polymerization technology.In this paper,four aminobisphenol-based cobalt metal complexes were used as catalysts to mediate the homopolymerization of monomeric acrylamide(AM),while mediate the copolymerization of polar monomer vinyl acetate(VAc),tert-butyl acrylate(t BA)and the polar monomer styrene(St).The copolymers were characterized by NMR,gel permeation chromatography(GPC),field emission scanning electron microscopy and field emission transmission electron microscopy.(1)Solution polymerization and dispersion polymerization of acrylamide were mediated by four amine bisphenol cobalt metal complexes.And the PAM with narrow molecular weight distribution(1.1-1.5)was obtained;monomer conversion increased with time,and conversion rate was as high as 93.9%at 280 min;additionally in alcohol/water system the polymer emulsion has good fluidity and stability,and the polymer powder exhibits a uniform sphere under scanning electron microscopy.(2)The sequential syntheses of well-defined poly(vinyl acetate)-block-polystyrene copolymer(PVAc-b-PS)and poly(tert-butyl acrylate)-block-polystyrene copolymer(Pt BA-b-PS)were challenging due to inactive vinyl acetate(VAc)monomer and active styrene(St)monomer.Sequential syntheses of VAc and St monomer were carried out by organometallic mediated radical polymerization(OMRP)and catalytic chain transfer(CCT)by using low-cost,highly active and versatile amino-bis(phenolate)cobalt complex.PVAc and Pt BA obtained via solution polymerization mediated by cobalt complex and initiated by azobisisobutyronitrile(AIBN),as macro-initiators,initiated dispersion polymerization of styrene to achieve PVAc-b-PS and Pt BA-b-PS with lower polydispersity(?1.8)for the first time.Linear kinetics with different feeding ratios of St and macro-initiator were obtained and the number-average molecular weight(M_n)increased linearly with monomer conversion.Synthesized block copolymers were characterized by Gel Permeation Chromatography,nuclear magnetic resonance spectroscopy,scanning electron microscopy.(3)About 8-15nm magnesium silicate nanotubes were used in the polymerization of vinyl acetate and copolymerization of t BA and styrene.In the experiment,the confinement effect of tubular magnesium silicate on polymerization was explored.PVAc with a narrow molecular weight distribution(PDI=1.9)and Pt BA-b-PS with a molecular weight distribution(PDI=2.5)were synthesized in magnesium silicate nanotubes.