Surface restructuring behavior of various types of poly(dimethylsiloxane) in water detected by SFG
Surface restructuring behavior of various types of poly(dimethylsiloxane) in water detected by SFG
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DOI：
10.1021/la049327u
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发表时间：
2004-11-09
期刊：
影响因子：
3.9
通讯作者：
Chen, Z
中科院分区：
文献类型：
--
作者：
Chen, CY;Wang, J;Chen, Z
用和频产生（SFG）振动谱研究了几种不同的聚二甲基硅氧烷（PDMS）材料，四乙氧基硅烷固化端羟基PDMS (TEOS-PDMS)，铂固化端乙烯基PDMS (Pt-PDMS)，铂固化端乙烯基聚二苯基硅氧烷-共聚二甲基硅氧烷（PDPS-co-PDMS）和PDMS-共聚苯乙烯（PDMS-co- ps）共聚物在空气和水中的表面结构。从空气和水中的所有PDMS表面收集的SFG光谱都以甲基拉伸为主，表明所有表面都主要被甲基覆盖。除了表面占主导地位的甲基外，在空气中也检测到Pt-PDMS表面的一些- si - ch2 - ch2 -基团，它们存在于交联点上。对甲基在PDMS表面的平均取向角和角度分布进行了评价。在水中所有的PDMS表面都观察到甲基的表面重组。当与水接触时，所有PDMS表面上的甲基都向表面倾斜。研究了几种PDMS表面在水中的详细重组行为以及分子量对重组行为的影响。为了比较，除了空气和水外，还研究了上述PDMS材料在非极性溶剂FC-75中的表面结构。通过比较苯基在PDPS-co-PDMS和PS-co-PDMS表面对水的不同反应，我们已经证明了表面苯基的重组行为是如何受到它们所连接的分子链的结构柔韧性的影响的。
Surface structures of several different poly(dimethylsiloxane) (PDMS) materials, tetraethoxysilane-cured hydroxy-terminated PDMS (TEOS-PDMS), platinum-cured vinyl-terminated PDMS (Pt-PDMS), platinum-cured vinyl-terminated poly(diphenylsiloxane)-co-poly(dimethylsiloxane) (PDPS-co-PDMS), and PDMS-co-polystyrene (PDMS-co-PS) copolymer in air and water have been investigated by sum frequency generation (SFG) vibrational spectroscopy. The SFG spectra collected from all PDMS surfaces in both air and water are dominated by methyl group stretches, indicating that all the surfaces are mainly covered by methyl groups. Other than surface-dominating methyl groups, some -Si-CH2-CH2- moieties on the Pt-PDMS surface have also been detected in air, which are present at cross-linking points. Information about the average orientation angle and angle distribution of the methyl groups on the PDMS surface has been evaluated. Surface restructuring of the methyl groups has been observed for all PDMS surfaces in water. Upon contacting water, the methyl groups on all PDMS surfaces tilt more toward the surface. The detailed restructuring behaviors of several PDMS surfaces in water and the effects of molecular weight on restructuring behaviors have been investigated. For comparison, in addition to air and water, surface structures of PDMS materials mentioned above in a nonpolar solvent, FC-75, have also been studied. By comparing the different response of phenyl groups to water on both PDPS-co-PDMS and PS-co-PDMS surfaces, we have demonstrated how the restructuring behaviors of surface phenyl groups are affected by the structural flexibility of the molecular chains where they are attached.