Studies on the effects of the alkyl group on the surface segregation of poly(n-alkyl methacrylate) end-capped 2-perfluorooctylethyl methacrylate films.
Studies on the effects of the alkyl group on the surface segregation of poly(n-alkyl methacrylate) end-capped 2-perfluorooctylethyl methacrylate films.
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DOI：
10.1016/j.jcis.2011.03.011
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发表时间：
2011-07
影响因子：
9.9
通讯作者：
Juping Yang;D. Yuan;Bin Zhou;Jie Gao;H. Ni;Li Zhang;Xinping Wang
中科院分区：
文献类型：
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作者：
Juping Yang;D. Yuan;Bin Zhou;Jie Gao;H. Ni;Li Zhang;Xinping Wang
采用差示扫描量热法、角分辨XPS分析、接触角测量和X-射线衍射仪研究了不同端基含量的聚甲基丙烯酸正烷基酯(PnAMA-EC-PFMA)的表面偏析行为。结果表明，在聚合物链端FMA单元数目相同的情况下，随着聚甲基丙烯酸烷基链上碳原子数的增加，氟的偏析程度(Q)增大。用一个FMA单元(PODMA160-EC-PFMA1.0)封端的聚甲基丙烯酸正十八酯(PODMA160-EC-PFMA1.0)薄膜5 nm深处的表面氟含量是本体水平的208倍。这些观察到的Q值差异是由于末端封端的聚合物在溶液中的聚集结构、当时烷基侧链的柔韧性和结晶度所致。当非氟嵌段为完全无定形时，端基聚合物在溶液中的分子聚集结构对氟化部分在所得膜上的表面偏析起重要作用。然而，当非氟嵌段为晶态时，结晶度将大大增强含氟部分的偏析。
The effects of the alkyl group on the surface segregation of poly(n-alkyl methacrylate) end-capped with various numbers of units of 2-perfluorooctylethyl methacrylate (FMA) (PnAMA-ec-PFMA) were investigated by differential scanning calorimetry, angle-resolved XPS analysis, contact angle measurements, and X-ray diffraction (XRD). The results show that with similar numbers of FMA units at the polymer chain end the extent of fluorine segregation (Q) increased with increasing the number of carbon atoms in the siden-alkyl chains of poly(n-alkyl methacrylate). The surface fluorine content within 5 nm deep of the film of poly(n-octadecyl methacrylate) end-capped with one FMA unit (PODMA160-ec-PFMA1.0) was 208-fold higher than that of the bulk level. These observed differences inQvalues were found due to the aggregate structure of the end-capped polymers in the solution, the flexibility, and the crystallinity of then-alkyl side chains. When the nonfluorinated block was completely amorphous, the molecular aggregate structure of the end-capped polymers in the solution played an important role in the surface segregation of the fluorinated moieties on the resulting film. However, when the nonfluorinated block was crystalline, crystallinity would enhance greatly the segregation of the fluorinated moieties.