不同相对分子质量两亲聚合物的分级及溶液黏弹性

Grading and Viscoelastic Properties of Amphiphilic Polymer with Different Molecular Weight

受聚合工艺的影响,两亲聚合物具有一定的相对分子质量分布范围,不同相对分子质量组分的结构与性能存在一定差异。为了揭示不同分子结构的两亲聚合物组分对性能的影响规律,采用双梯度淋洗法,对两亲聚合物AP-3按相对分子质量大小进行分级,得到了不同相对分子质量梯度的两亲聚合物分离组分,优化改进了分级装置,筛选了沉淀-溶解对,考察了不同级分两亲聚合物的红外光谱特征、增黏和流变特性。结果表明:乙醇-水构成的沉淀-溶解对能够有效地分离两亲聚合物中相对分子质量较小的组分,丙酮-水构成的沉淀-溶解对能够有效地分离两亲聚合物中相对分子质量较大的组分;分离后大、小分子组分与原聚合物分子结构相似,区别在于相对分子质量和疏水基团含量不同;分离出的大分子组分及小分子组分增黏能力和流变性均低于原聚合物,结构差异的大、小分子组分聚合物在溶液中的协同作用使原聚合物有更好的黏弹性能。

Influenced by the polymerization process, amphiphilic polymer （AP） has a wide distribution range of the molecular weight, and components with different molecular weight possess various structures and properties. In order to discover the effect of the components with different structures on the property ofAP, fractions of AP with a series of molecular weight were obtained by means of double-gradient elution, and the result of separation was discussed. The elution device was optimized and improved, and precipitation-dissolve systems were compared and screened. AP fractions of different molecular weight are analyzed by FT-IR spectrum, and thickening and rheology properties were studied systematically. The experimental results showed that the precipitation-dissolve system of ethanol-water could classify the portion of the smaller molecule of AP effectively, while the precipitation-dissolve system of acetone-water had a good performance on the portion of the bigger molecule of AP. Different elution fractions had the similar molecular structure with the original sample, and the differences lied in the size of molecular weight and the content of hydrophobic groups per mass. The viscosity-increasing ability and rheological properties of the bigger molecule and the smaller molecule components were lower than those before separation. There was synergistic effect between the smaller molecules and the bigger molecules in the solution, which endowed the original amphiphilic polymer better thickening and theology properties.