TITLE

Dynamic 2D IR spectroscopy of poly(&Vegr;-caprolactone)

AUTHOR(S)
Marcott, C.; Dowrey, A. E.; Story, G. M.; Noda, I.
PUB. DATE
March 2000
SOURCE
AIP Conference Proceedings;2000, Vol. 503 Issue 1, p77
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Dynamic two-dimensional infrared (2D IR) spectroscopy evolved from the analysis of orthogonal spectral data sets generated by a rheo-optical dynamic IR linear dichroism (DIRLD) measurement of polymer films undergoing a small-amplitude oscillatory deformation. DIRLD spectroscopy has provided new insight into polymer deformation mechanisms and how they change as a function of temperature and deformation frequency. In general, we observe that polymer chains do not reorient as rigid units when deformed on a ms-μs time scale. There exists a surprising degree of independent reorientational motions at the submolecular segmental scale. Such independent motions are readily analyzed by the 2D correlation method. The technique has also proven useful in understanding submolecular interactions of polymer blend, additive, or block copolymer components as a function of viscoelastic state. When the observed time-dependent spectral variation resulting from a DIRLD experiment is represented in the form of a 2D IR map, a clear enhancement of the spectral resolution of broad IR band contours often results. Dynamic 2D IR spectroscopy was used to study poly(ε-caprolactone) (PCL) in the mid-IR spectral region. PCL was examined in order to determine the effects of temperature on its morphology and physical properties. Below the glass-to-rubber transition temperature (T[sub g]), the amorphous component of PCL is “frozen”, and responds much more strongly to the external strain perturbation than it does at room temperature. In addition, the carbonyl group is the primary site of reorientation in PCL at temperatures near T[sub g]. Above T[sub g], most of the reorientation in response to the small-amplitude strain perturbation is occurring in the crystalline PCL component. Residual amounts of tightly bound water are also observed to reorient independently of the crystalline component above T[sub g]. © 2000 American Institute of Physics.
ACCESSION #
5984951

 

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