Infrared spectroscopy method reveals hydrogen bonding and intermolecular interaction between components in polymer blends

An infrared spectroscopy method was devised to uncover evidence of hydrogen bonding and intermolecular interaction between components in solid poly(lactic acid) (PLA) and poly(hydroxyester ether) (PHEE) blends. The method compares Gaussian/Lorentzian deconvoluted infrared spectra of the polymer blends with deconvoluted spectra of weight ratio-equivalent mixtures of the physically separated polymers. Infrared spectra of polymer blends, where hvdrogen bonding exists, differ from spectra of physical mixtures of the polymers. Deconvoluting spectra of the blends into their underlying peaks revealed theoretically expected differences between hydrogen-bonded and nonhydrogen bonded components. The findings are supported by differential scanning calorimetry, scanning electron microscopy, and mechanical rheometry studies. The new method, differential spectral deconvolution, afforded a quantitative estimate of the extent of hydrogen bonding between PLA and PHEE and could therefore be used to measure the degree of interaction between components in thermoplastic blends. This technique is superior to conventional spectral subtraction and it should be applicable to intimate mixtures or solid solutions in general. (c) 2005 Wiley Periodicals, Inc.