Two-Dimensional Correlation Vibrational Spectroscopy Study on Intermolecular Interactions in Polymer Blends

二维红外、拉曼、近红外本文应用二维红外、二维拉曼、二维近红外相关光谱和异相二维相关光谱研究了无规聚苯乙烯（PS）和聚苯乙烯（PS）共混物中的构象变化和特异性相互作用（2，6-二甲基-1，4-亚苯基醚）（PPE），发现二维振动相关光谱在检测一维光谱中不容易识别的谱带方面是强大的。二维同步相关分析分离了PS和PPE的近红外谱带，二维异步相关分析产生交叉峰，表明共混物中存在特异性相互作用或构象变化。利用二维拉曼-近红外异质相关光谱研究了聚甲基丙烯酸甲酯（PMMA）/聚对乙烯基苯酚（PVPh）共混体系中的分子间相互作用。研究了10种PMMA/PVPh共混物，其PVPh含量从1到10wt%不等。首先应用二维异质相关光谱技术分离出聚乙烯吡咯烷酮（PVPh）的弱振动带和聚甲基丙烯酸甲酯（PMMA）的强振动带，然后研究了PMMA和PVPh之间的分子间相互作用。Raman-NIR异相关分析检测到PVPh的氢键羟基在6764和4637 cm-1处的两个谱带<-1>，以及PMMA的氢键羰基在5052 cm-1处的一个谱带<-1>。

Two-dimensional infrared, Raman, near-infrared (2D IR, 2D Raman, 2D NIR) correlation spectroscopy and hetero 2D correlation spectroscopy have been applied to the studies of the conformational changes and specific interactions in various polymer blends such as those of atactic polystyrene (PS) and poly(2,6-dimethyl-1,4-phenylene ether)(PPE), It was found that 2D vibrational correlation spectroscopy is powerful in detecting bands which are not readily identified in onedimensional spectra. The 2D synchronous correlation analysis separates the NIR bands of PS from those of PPE.The 2D asynchronous correlation analysis produces cross peaks that are indicative of the specific interaction or the conformational change in the blends. It is concluded from the 2D correlation analysis that not only the phenyl rings of PS and PPE but also the CH_3 groups of PPE play important roles in the formation of the blends.The 2D Raman-NIR heterospectral correlation spectroscopy was employed to investigate intermolecular interactions in the blends of poly(methyl methacrylate) (PMMA) and poly(4-vinyiphenol) (PVPh). Ten blends of PMMA/PVPh studied contained small PVPh contents from 1 to10 weight percentages. 2D hetero correlation spectroscopy was first applied to separate the weak vibrational bands of the minority PVPh from the strong bands of the principal PMMA, and then to detect the intermolecular interactions between PMMA and PVPh. The Raman-NIR hetero-correlation analysis detects two bands at 6764 and 4637 cm_<-1> for the hydrogen-bonded hydroxyl group of PVPh, and one band at 5052 cm_<-1> for the hydrogen-bonded carbonyl group of PMMA.All these bands are not identifiable from the one-dimensional spectra.