非溶剂添加剂对共聚砜铸膜液体系及膜性能与结构的影响

THE EFFECT OF NONSOLVENT ADDITIVES ON POLY(PHTHALAZINONE ETHER SULFONE)MEMBRANE-FORMING SYSTEMS AND MEMBRANE PROPERTIES AND STRUCTURE

以含二氮杂萘酮结构的新型共聚砜为膜材料 ,通过浊点滴定法和特性粘数的测定研究了几种非溶剂添加剂对铸膜液体系的影响 .并由共聚砜 NMP 添加剂三组分相分离曲线数据计算了共聚砜的Θ溶剂中NMP与添加剂的比例 ,考察了添加剂EGME用量对共聚砜超滤膜结构和性能的影响 .发现当EGME NMP接近Θ组成时膜性能发生突变 ,在EGME NMP低于Θ组成时 ,膜的水通量随添加剂用量的增大而增大 ,截留率基本不变 .

Polymer precipitation curves for the ternary systems PPES/ NMP/ additive were determined by a titration method. Membrane-forming additives used were H-2O, MeOH, EE, EGME and BO. The position of the precipitation curve in the triangle phase diagram reflects the effect of the type of nonsolvent additive on the ternary systems. In addition, the effect can also be demonstrated by the different dropping rate of the intrinsic viscosities caused by various nonsolvent additives. These results indicate that the polymer conformation in solutions varies with the use of different additives. Besides the type of nonsolvent additive, the amount of nonsolvent additive can alter the polymer conformation in solution somewhere. Along the path leading from the initial starting point up to near the precipitation point, a stage would be reached in which the NMP/nonsolvent mixture becomes a theta-solvent for the polymer, and the macromolecules would assume an unperturbed conformation. NMP/nonsolvent theta- compositions were determined by the method of Elias using precipitation point data. A series of ultrafiltration membranes were made from poly( phthalazinone ether sulfone) with NMP as solvent. The membrane structure changes with the increase of the content of nonsolvent additive. When the content of EGME additive is close to 40 wt % - the theta- composition of NMP/EGME mixture, the structure and properties of membranes change greatly.