Surface and interfacial segregation in blends of polystyrene with functional end groups and deuterated polystyrene.
Surface and interfacial segregation in blends of polystyrene with functional end groups and deuterated polystyrene.
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DOI：
10.1021/la700418j
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发表时间：
2007-05
期刊：
影响因子：
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通讯作者：
D. Kawaguchi;Keiji Tanaka;N. Torikai;A. Takahara;T. Kajiyama
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文献类型：
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作者：
D. Kawaguchi;Keiji Tanaka;N. Torikai;A. Takahara;T. Kajiyama
通过 X 射线光电子和二次离子质谱结合中子反射率测量，研究了链端化学对聚苯乙烯 (hPS)/氘化聚苯乙烯 (dPS) 对称共混物中表面和界面偏析的影响。使用α,omega-氟烷基和α,omega-羧基封端的聚苯乙烯（α,omega-hPS(Rf)2 和α,omega-hPS(COOH)2）作为末端官能化聚合物；前者具有较低表面能的链端，后者与主链相比具有较高的表面能。在 α,omega-hPS(Rf)2/dPS 共混膜的情况下，尽管 hPS 片段的表面能略高于 dPS 片段的表面能，但由于 Rf 基团的表面局域化，α,omega-hPS(Rf)2 在表面富集。相反，在α,omega-hPS(COOH)2/dPS共混膜的情况下，dPS优先在表面偏析。这可能是由于 COOH 末端的表面耗尽以及 COOH 末端的氢键分子间缔合产生的 α,omega-hPS(COOH)2 的表观分子量增加以及 hPS 和 dPS 链段之间的表面能差异。有趣的是，对于 α,omega-hPS(Rf)2/dPS 和 α,omega-hPS(COOH)2/dPS 共混膜，Rf 和 COOH 链端均分配到基材界面，导致两种共混物的 hPS 组分在基材界面处偏析。结果表明，聚合物共混物中的表面和界面偏析可以通过将官能团掺入一种组分的端部来调节。
The effect of chain-end chemistry on surface and interfacial segregation in symmetric blends of polystyrene (hPS)/deuterated polystyrene (dPS) has been investigated by X-ray photoelectron and secondary ion mass spectroscopy in conjunction with neutron reflectivity measurements. Alpha,omega-fluoroalkyl- and alpha,omega-carboxy-terminated polystyrenes (alpha,omega-hPS(Rf)2 and alpha,omega-hPS(COOH)2) were used as end-functionalized polymers; the former possesses chain ends with lower surface energies, and the latter possesses higher surface energies compared with that of the main chain. In the case of an alpha,omega-hPS(Rf)2/dPS blend film, alpha,omega-hPS(Rf)2 was enriched at the surface owing to the surface localization of the Rf groups, although the surface energy of the hPS segments was slightly higher than that of the dPS ones. On the contrary, in the case of an alpha,omega-hPS(COOH)2/dPS blend film, dPS was preferentially segregated at the surface. This may be due to a surface depletion of COOH ends and an apparent molecular weight increase of alpha,omega-hPS(COOH)2 produced by a hydrogen-bonded intermolecular association of COOH ends in addition to the surface energy difference between hPS and dPS segments. Interestingly, both Rf and COOH chain ends were partitioned to the substrate interface for the alpha,omega-hPS(Rf)2/dPS and alpha,omega-hPS(COOH)2/dPS blend films, resulting in the segregation of the hPS component at the substrate interface for both blends. The results presented imply that surface and interfacial segregation in polymer blends could be regulated by incorporating functional groups into the end portions of one component.