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以甲基丙烯酸2-全氟辛基乙酯(FOEMA)分别和不同烷烃链长丙烯酸酯(RA,CH2CHCOOCn H2n+1,n=4,8,12,16,18)为单体,用自由基聚合法合成了一系列的含氟丙烯酸酯共聚物,通过X射线衍射(XRD)和示差扫描量热法(DSC)对共聚物进行了表征,发现结晶性与丙烯酸酯的烷烃链长度密切相关,当n=4,8,12时,在常温下不具有结晶性,当n=16,18时在常温下结晶,以碳氢侧链结晶为主.由DSC谱图测出了各共聚物的结晶焓.通过热力学计算,发现n=16时,恒压熵变值最小,说明该共聚物有序性最好.用多功能光电子能谱仪(XPS)测定了共聚物表面氟碳比(F/C)和官能团组成,并用接触角测试仪测定了与正十六烷和水的静态接触角.氟碳比随着烷烃侧链的增长而增大,从0.39增加到0.71.当n=16和18,表面非极性基团(—CF3和—CF2)明显增加,极性基团(—C O和—C—O—C O)明显减少导致了与正十六烷的静态接触角明显增大.结果表明共聚物中的碳氢侧链由于结晶导致全氟链段在成膜时更易于向涂膜-空气界面迁移,从而提高共聚合物表面疏水疏油性.
With 2-perfluorooctyl ethyl methacrylate (FOEMA) and different alkane chain length acrylate (RA, CH2CHCOOCn H2n + 1, n = 4,8,12,16,18) as monomers, with free radicals A series of fluorine-containing acrylate copolymers were synthesized by polymerization. The copolymers were characterized by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It was found that the crystallinity was closely related to the length of alkane chain of acrylate. When n = 4, 8, and 12, it has no crystallinity at normal temperature and crystallizes at room temperature when n = 16 and 18, The enthalpy of crystallization was found by thermodynamic calculation and it was found that when n = 16, the constant entropy change value was the smallest, indicating the best orderliness of copolymer.The fluorocarbon ratio (F / C) and functional groups, and the static contact angles with n-hexadecane and water were measured with a contact angle tester.The fluorocarbon ratio increased with the increase of paraffin side chain, from 0.39 to 0.71. When n = 16 And 18, the surface non-polar groups (-CF3 and -CF2) increased significantly, the significant decrease of polar groups (-CO and -C-O-CO) led to the significant increase of the static contact angle with n-hexadecane .The results show Hydrocarbon side chain of copolymer due to crystallization perfluoro segment to more easily during the film coating - migration-air interface, thereby increasing the total surface of the hydrophobic polymer oleophobic.