配位催化苯乙烯乳液聚合的动力学研究

以Ni(COD)2和含磷、氧配体为催化剂,利用乳液聚合法合成了间规聚苯乙烯.对产物进行了13C-NMR、1H-NMR、GPC、TEM、DSC、TG等表征.在此反应体系下,最佳聚合条件为:乳化剂用量为1.50 g,St]0=1.79 mol·L-1,T=60℃,t=2h,Ni(COD)2]=1.102 mmol·L-...

KINETICS OF THE COORDINATIVE CATALYTIC EMULSION POLYMERIZATION OF STYRENE

Syndiotactic polystyrene was synthesized by emulsion polymerization using Ni(COD)2 and ligands containing P and O as catalyst.The reaction kinetics of the above process was studied.The product was characterized with 13C-NMR,1H-NMR,GPC,TEM,DSC and TG etc.The best polymerization condition for this reaction system was found to be:emulsifier 1.50 g,0=1.79 mol·L-1,T=60℃,t=2 h,Ni(COD)2]=1.10 mmol·L-1,the conversion was 78%.The activity of the catalyst was 662.14 gPS·(gNi·h)-1.The emulsion particle size was 100~120 nm from the results of particle size analysis and TEM techniques.Very good thermal stabilities of latex are observed in the temperature range of ambient temperature up to ca.376℃.The GPC analysis results show that:the weight average molecular weight Mw is 1.64×106,while the number-average molecular weight Mn is 9.79×105 and the width of molecular weight distribution is 1.6.The 13C-NMR,1H-NMR and TG analysis results proved the syndiotactic structure.The polymers exhibit glass transition temperature of Tg=114.95℃.The rate of polymerization(Rp) was found to be dependent on the monomer,catalysts concentrations.Preliminary study on the kinetics of the polymerization indicates that:the apparent activation energy Ea is 20.76 kJ/mol,the rate equations are:Rp=1.687×0.241Ni(COD)2]0.542(when ≤1.79 mol·L-1),Rp=0.03683×-0.187Ni(COD)2]0.542(when >1.79 mol·L-1).