Two-dimensional infrared correlation spectroscopic studies of polymer blends: conformational changes and specific interactions in polytetrahydrofuran / cholesteryl palmitate blends

摘要

Generalized two-dimensional infrared (2D IR) correlation spectroscopy has been applied to the study of the conformational changes and specific interactions in blends of polytetrahidrofuran (PTHF) and cholesteryl palmitate (CP). IR spectra have been measured for CID, PTHF, and their blends of different compositions: 2/98, 4/96, 6/94, 10/90, 16/84, 32/68, 64/36, and 80/20. In order to apply 2D IR correlation analysis the samples are divided into two sets for 2D: set A with high PTHF content 0/100, 2/98, 4/96, 6/94, 10/90, 16/84, 32/68 CP/ PTHF and set B with high CP content 64/36, 80/20 and 100/0 CP/PTHF. The 2D IR synchronous correlation analysis separates the bands of PTHF from those of CP. The 2D IR asynchronous correlation analysis produces cross-peaks that are indicative of the specific interaction or the conformational change in the blends. Ten "blend bands" are identified at 2916, 1441, 1243, 1227, 1106 and 967 cm(-1) (CP) and 2802, 2862, 1492 and 1127 cm 1 (PTHF), whose origin has been attributed to the molecular level changes induced by mutual influence of the components which involve aliphatic CH and C-O-C groups of CP and PTHF, respectively.