聚丙烯-聚乙二醇嵌段共聚物的制备及其对聚丙烯薄膜的表面改性

采用双端羧基聚丙烯(PP)与聚乙二醇单甲醚(MPEG)进行酯化反应,制备了不同嵌段长度的嵌段共聚物PEG-b-PP-b-PEG,并将其作为大分子表面改性剂与PP共混制得薄膜。采用衰减全反射红外(ATR-FTIR)、接触角测试仪和原子力显微镜(AFM)分析表征了薄膜的表面组成与性能。研究表明,PEG-b-PP-b-PEG可以改善PP薄膜的亲水性和表面极性,使表面自由能增大;薄膜表面性能的改善程度取决于薄膜中PEG链段的质量分数以及嵌段共聚物的嵌段分子量;随着共混薄膜中PEG链段质量含量增加,薄膜的水接触角迅速下降,表面自由能增大;随嵌段共聚物中PP嵌段分子量以及PEG嵌段分子量的下降,薄膜水接触角减小,表面自由能增大;当嵌段共聚物中PP嵌段和PEG链段分子量均为1 000左右时,对PP薄膜表面亲水性的改善效果较好。

Preparation of Polypropylene and Polyethylene Glycol Block Copolymers and Its Surface Modification of Polypropylene Films

Esterification reactions of dicarboxyl-capped polypropylene(PP) with methoxy polyethylene glycol (MPEG) were conducted to prepare block copolymers of polypropylene and polyethylene glycol (PEG-b-PP-b-PEG) with different block chain molecular weights. PEG-b-PP-b-PEG was blended with polypropylene films, as macromolecular surface modifiers, to prepare blend films. Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR), Contact Angle Tester and Atomic Force Microscope (AFM) were used to characterize surface composition and properties of the blend films. Results showed that PEG-b-PP-b-PEG could improve the surface hydrophilicity and polarity of the PP films, and the enhancement of surface properties was dependent on the mass fraction of PEG chain segments in the films and the block chain molecular weight of PEG-b-PP-b-PEG. With the increase of PEG segment chains mass fraction in the film, water contact angle of the films decreased, and surface free energy increased. As the chain molecular weight of PEG block and/or PP block in PEG-b-PP-b-PEG decreased, water contact angle of the films also decreased, and surface free energy increased too. When molecular weights of both PEG block and PP block in PEG-b-PP-b-PEG were around 1 000, an enhanced surface hydrophilicity modification effect was obtained.