Thermal Response of Surface Grafted Two-Dimensional Polystyrene (PS)/Polyvinylmethylether (PVME) Blend Films
Thermal Response of Surface Grafted Two-Dimensional Polystyrene (PS)/Polyvinylmethylether (PVME) Blend Films
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DOI：
10.1021/ma9021696
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发表时间：
2010-01-26
期刊：
影响因子：
5.5
通讯作者：
Gutmann, Jochen S.
中科院分区：
文献类型：
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作者：
Lenz, Sebastian;Nett, Sebastian K.;Gutmann, Jochen S.
这项工作表明，二维聚合物薄膜中的相分离可以通过使用熵约束接枝点来调节。介绍了用表面锚定的二苯甲酮衍生物表面接枝二维聚苯乙烯(PS)/聚乙烯基甲醚(PVME)共混膜的实验结果。与未接枝的2D薄膜相比，使用较低的接枝点密度可以将共混物的低临界溶液温度(LCST)提高到室温以上。高度受限的薄膜没有表现出聚合物-聚合物相分离。除了用表面探针显微镜(SPM)进行的原位结构分析、微束尺寸的掠入射小角X射线散射(MU-GISAXS)和微束X射线反射率(MU-XRR)之外，利用纳米机械悬臂传感器(NCS)阵列进行的表面应力研究详细地揭示了相分离的机理。结果表明，相分离导致了主要的吸引熵弹簧机制，而表面能和界面能的变化导致了相反的排斥效应。
This work shows that phase separations in 2D polymer films can be tuned by employing entropically constraining grafting points. We present experimental results oil surface-grafted 2D polystyrene (PS)/polyvinylmethylether (PVME) blended Films using surface-anchored benzophenone derivates. In contrast with 2D films that have not been grafted, it was possible to raise the blended lower critical solution temperature (LCST) above room temperature by using low grafting point densities. Highly constrained films did not show polymer-polymer phase separation. In addition to the in situ structural analysis performed with surface probe microscopy (SPM), mu-beam-sized grazing incidence small-angle X-ray scattering (mu-GISAXS), and mu-X-ray reflectivity (mu-XRR), surface stress investigations performed using nano mechanical cantilever sensor (NCS) arrays gave detailed insight into the phase separation mechanism. Phase separations were shown to result in dominating attractive entropic spring mechanisms with opposing repulsive effects resulting from surface and interfacial energy changes.