| Abstract
| - Generalized two-dimensional near-infrared (2D NIR) correlation spectroscopy has been applied to the studyof the conformational changes and specific interactions in blends of atactic polystyrene (PS) and poly(2,6-dimethyl-1,4-phenylene ether) (PPE). NIR diffuse reflectance spectra have been measured for PS, PPE, andtheir blends of different compositions: PS/PPE = 90/10, 70/30, 50/50, 30/70, 10/90. The samples are dividedinto two sets for 2D correlation: set A with high PS content (PS/PPE = 100/0, 90/10, 70/30) and set B withhigh PPE content (PS/PPE = 50/50, 30/70, 10/90). The 2D synchronous correlation analysis separates thebands of PS from those of PPE. The 2D asynchronous correlation analysis produces cross-peaks that areindicative of the specific interaction or the conformational change in the blends. Two “blend bands” areidentified at 8443 cm-1 (PPE) and 6887 cm-1 (PS), whose origin has been attributed to the molecular levelchanges induced by the formation of blends. It is found that the NIR region of 7700−6400 cm-1 is mostsuitable for 2D analysis of the specific interaction between PS and PPE, while the region of 5600−4900cm-1 is best for 2D analysis of the conformational features common to both sets A and B, and the region of4750−4300 cm-1 is best for conformational features unique to set A or B. It is concluded that not only thephenyl rings of PS and PPE but also the CH3 groups of PPE play important roles in the formation of theblends.
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