聚苯乙烯-g-聚乙二醇的制备及其表面改性作用

通过沉淀聚合方法,利用自由基共聚制备了苯乙烯-顺丁烯二酸酐共聚物(SMA),利用SOCl2的酰氯反应,在SMA大分子链上接枝聚乙二醇侧链,制备了聚苯乙烯-g-聚乙二醇(PEG-g-PS)的大分子表面改性剂。利用大分子表面改性剂在聚苯乙烯基体中具有选择性迁移扩散的特性,实现了对聚苯乙烯薄膜表面极性的改善作用。采用衰减全反射傅立叶变换红外光谱仪和表面静态接触角法检测了聚苯乙烯的表面极性。结果发现,PEG-g-PS上的聚醚链段可以有效的富集在聚合物表面,明显改善PS的表面极性和亲水性,表面极性可提高3倍,达到11.6mN/m。同时,大分子表面改性剂和聚苯乙烯基体间有一定的相容性,有效地克服了小分子表面改性剂容易流失,改性寿命较短的重要缺陷,使表面改性的持久性充分增加,实现对聚合物表面改性效果终生化的目的。而且大分子表面改性剂在极性溶剂的诱导作用下,可以实现进一步的迁移扩散,充分提高了聚苯乙烯的表面极性。

Preparation of Polystyrene-g-poly ( ethylene glycol) and Its Surface Modification for Polystyrene

The method of precipitation polymerization was employed to synthesize styrene-co-maleic anhydride copolymers(SMA). The comb-like amphiphilic copolymers based on maleic anhydride copolymer backbone and PEG grafts(PEG-g-PS) were prepared at high conversion rate by utilizing thionyl chloride to convert acid anhydride groups into acyl chloride groups. When this amphiphilic copolymer was used as the surface modifying macromolecules, the chain segments of polyether on PEG-g-PS could preferentially aggregate on the surface of PEG-g-PS/PS blends to increase the surface polarity of PS. The surface polarity of the blends could reach to 11.6 mN/m, which is about three times higher than that of pure PS(3.5 mN/m). Because of the compatibility between PEG-g-PS and PS, the effective duration of surface modification by PEG-g-PS is greatly extended and the surface functionalization even becomes permanent for the material. Furthermore, more polyether chain segments on PEG-g-PS could selectively migrate to the surface by the inducement of polar solvent. The attenuated total reflectance Fourier transform infrared spectroscopy and contact angle measurement were used to detect the surface structure and surface properties.