超临界CO2中丙烯酸含氟酯疏水改性聚丙烯酸的合成

研究了在超临界二氧化碳条件下 ,丙烯酸 1,1 二氢全氟辛酯 (FOA)对聚丙烯酸疏水改性的共聚反应 .发现与通常聚合方法相比含氟丙烯酸酯的产率得到提高 ;反应时间从 2 4h缩短到 4h ;所得产物的后处理也更容易 .同时发现温度对反应有影响 ,含氟酯单体在低温 (T <5 5 0℃ )时活性高于丙烯酸单体 ,在高温 (T >6 0 0℃ )时丙烯酸活性提高较大 .而共聚物水溶液粘度随pH值变化先上升后下降 ,在pH =5 0出现峰值 ,显示其中有分子间缔合存在 .与改性聚丙烯酰胺不同 ,改性聚丙烯酸水溶液粘度随FOA含量的增加而单调上升 ,也证明了分子间缔合的存在

COPOLYMERIZATION OF FLUOROCARBON-MODIFIED POLY(ACRYLIC ACID) IN SUPERCRITICAL CARBON DIOXIDE

Copolymer of 1,1-dihydroperfluorooctyl acrylate (FOA) and acrylic acid (AA) was obtained in supercritical CO 2(SC-CO 2).Compared with the traditional methods,the yield ratio of FOA using SC-CO 2 is increased at lower temperature,the reaction time is shortened from 24 h to only 4 h,and the products are easier to be treated.At the same time it was found that temperature played an important role in these reactions.The FOA monomer is more active than the AA monomer in low temperature (T<55.0℃),but in high temperature(T>60.0℃)the activity of AA monomer improved greatly.The viscosity of aqueous solutions of the copolylmers rises up dramatically with the increase of fluorocarbon content,and the viscosity of the copolymers versus pH values shows a peak,both of results evidenced the hydrophobic association of macromolecules in solutions.