Fourier-transform infrared spectroscopic study of a fractional-complexed polymer blend

Abstract

FTIR spectroscopy and quantum chemical calculations have been used to explore the system of high-molecular mass pair of miscible polymers poly(N-methyldodecano-12-lactam) (PMDL) and poly(4-vinylphenol) (PVPh) in tetrahydrofuran (THF) that is known to undergo associative phase separation into a gel-like interpolymer complex and a soluble residual phase (RP). Using quantum chemical calculations, two types of hydrogen bonding interactions involving the CO group of PMDL and either one or two OH groups of PVPh were identified in the FTIR spectra of both the complex and RP. Although relatively small differences were found between the FTIR spectra of the complex and RP, detailed analysis of the CO stretching region revealed that in the complex, the stronger H-bonding interactions of the CO groups with two OH groups slightly outnumbered those in RP. In addition, a proof was added to the recent claim that fractionation accompanied the process of H-bond formation and complex precipitation but did not precede it. Finally, it was suggested that change in thermodynamic quality of solvent took place due to the complexation of the two polymers; the complex stability in a polar proton-donating solvent was tested as well.