甲基丙烯酸2-羟乙酯水溶液聚合与硫氰化钠的效应

<正> 甲基丙烯酸2-羟乙酯(HEMA)是一带有羟基的功能性单体,它可以在自由基聚合引发剂如过氧化苯甲酰、偶氮二异丁腈、过氧化二碳酸二异丙酯或氧化还原引发体系过硫酸盐-乙酸二甲胺基乙酯的作用下进行自由基聚合,我们已报道带有羟基的单体如HEMA、甲基丙烯酸羟丙酯(HPMA)及甲基丙烯酯3-甲氧基-2-羟丙酯(MHPMA)可用

THE AQUEOUS POLYMERIZATION OF 2-HYDROXYETHYLMETHACRYLATE AND THE EFFECT OF SODIUM THIOCYANATE

The radical polymerization of a well known functional monomer with hydroxy group such as 2-hydroxyethyl methacrylate (HEMA) in aqueous solution initiated with potassium persulfate (KPS) was studied. The polymerization rate and percentage of conversion increased as the concentration of KPS increased. Kinetic studies of aqueous solution polymerization of HEMA using KPS] =2.4 × 10-3mol/1 was made under different temperatures within the range of 35-50℃, and the overall activation energy of polymerization E. of HEMA using KPS as initiator was evaluated to be 33 Kcal/mol (138 KJ/mol). It was found that the amount of NaSCN played an important role on the peroxide initiated aqueous solution polymerization of HEMA. When the concentration of KPS and H2O2 were equal to 2.4 × 10-3 and 3.0× 10-3 mol/1 respectively, NaSCN would act as activator within the range of NaSCN]/KPS] =1-10, or NaSCN]/H2O2] =0.007-0.7, when these molar ratios increased then NaSCN would always show its inhibition or retardation effect and would lower the percentage of conversion. In the case of TBH, NaSCN would act as activator and increase the percentage of conversion.