Living Free Radical Polymerization of Styrene in the Presence of Sodium Nitrite and Iron(Ⅱ) Sulfate
- 化学化工－已发表论文 
[中文文摘]研究了NaNO2/FeSO4·7H2O存在下苯乙烯的活性自由基聚合.发现亚硝酸钠与硫酸亚铁反应生成的 NO能够与AIBN裂解的自由基,生成氧氮自由基,且能控制苯乙烯的自由基聚合.当 AIBN/NaNO2/FeSO4 ·7H2O的摩尔比为1/2.5/2.5时,得到分子量分布较窄,分子量在5万以下可控的聚合物,实测分子量与理论分子量相近.聚合过程中转化率随反应时间增长而增高,分子量随转化率增高而增大,具有典型活性自由基聚合的特征.经纯化后的聚苯乙烯可作为大分子引发剂,引发新加入单体的聚合,证明是活的高分子.[英文文摘]Sodium nitrite is an quite inexpensive compound which can impart control to the radical polymerization of styrene initiated by AIBN.The polymerization of styrene in the presence of small amounts of sodium nitrite and iron(Ⅱ)sulfate was studied in this paper.The polymerization of styrene was living when the molar ratio of AIBN/NaNO2/FeSO4·7H2O was 1/2.5/2.5,the molecular weight polydispersities was <1.5,the experimental molecular weights of the polymers prepared using AIBN/NaNO2/FeSO4·7H2O were close to the theor etical molecular weight calculated from the ratio of styrene to AIBN.At molecular weights below 5×104 ,the agreement was excellent.As the molecular weight increased,this difference increased distinctly at molecular weights above 6 ×104, and the polydispersity also increased.With the increasing of the conversion of monomer ,the molecular weight of polymer evolved in a nearly linear fashion with increasing conversion.This linear relationship is characteristic of living polymerization and the nit roxide mediated f ree radical polymerizations of styrene.The diblock copolymers of styrene were prepared by adding styrene monomer to polystyrene macroinitiator and heating 16 h at 120 ℃.The polydispersities of all of the diblock copolystyrenes were low ,the real molecular weight of these copolymers was similar to the theoretical molecular weight. A typical low molecular weight ( Mn = 2. 53 ×103 )polystyrene prepared using AIBN/ NaNO2 / FeSO4 ·7H2O was confirmed by 1 HNMR.