Infrared spectroscopy, early polymer

Concerning the experimental side of polymer adsorption studies the quantity A was only measurable at the early stage of the study, but in 19SS the thickness of the adsorbed layer became accessible to measurement by a hydrodynamic method and in 1961 the quantity p was first determined by infrared spectroscopy. Ellipsometry came up in 1963, which enabled both the adsorbance and the thickness of the adsorbed layer to be measured simultaneously. 

In the early days of polymer chemistry before the mechanism of vinyl polymerization was understood, there was considerable speculation as to structures of vinyl polymers as it was not known whether the units were regularly head to tail, head to head, tail to tail, or random in arrangement. In the late thirties and early forties, we studied the reactions of many vinyl polymers such as polyvinyl chloride, polyvinyl alcohol, polymethyl vinyl ketone and polystyrene to try to settle this point,All proved to be head to tail structxires as was later predicted to be correct from the polymerization mechanism theory. Again I eii5)hasize that, at this time, infrared spectroscopy was in its infancy and NMR was unknown so structures needed to be established by chemical means. 

Whether a polymer is crystalline or not can be ascertained by X-ray diffraction. This technique played a valuable role in the early structural determinations of crystalline polymers. It still does. But it does have limitations as Krigbaum (1964) pointed out. Other techniques may be used for determining tacticity which do not require a crystalline sample. These include infrared and nuclear magnetic resonance spectroscopy. 

Early studies on PLLA mainly focused on the identification of characteristic bands to investigate the polymer crystallinity. Since Fourier transform infrared (FUR) spectroscopy is sensitive to the conformation and local molecular environment, this technique has also been used to elucidate the structure of the crystalline polymers. More recently, research on PLLA surface characterization using FTIR has been an object of interest. This section is divided into three parts structural analysis, surface characterization, and crystallization studies. 

Because of the strong coloration of PT, especially in the partly and fully oxidized state, resonance Raman spectroscopy has been employed suceessfully to elucidate the molecular structure and changes thereof as a function of applied electrode potential and other experimental parameters [930]. Resonance Raman and infrared spectra of polythiophene obtained ex situ under various, frequently unsatisfactorily defined experimental conditions have been reported [931-935]. These early results were, in part, inconsistent. In particular, the assignment of bands not found in the thiophene monomer to modes of the newly created polymer was repeatedly contradictory. 

Infrared emission has the potential to both identify and determine the relative concentration of oxidation products at the oxidation temperature. Emission spectroscopy is generally regarded as one of the most sensitive methods for detecting certain oxidation products and enables an easy way of obtaining real-time spectral information. This is particularly important when investigating the oxidation product distribution at the very early stages of polymer degradation. The rate of formation of carbonyl... 

An early compilation of established quantitative infrared polymer/additive methods was published [164] no update seems to be available. Various reviews on quantitative (surface) IR analysis have appeared [18,130,159,165,166,166a]. Several textbooks discuss basic considerations concerning quantitative analysis by vibrational spectroscopy [167-169]. Data processing techniques for quantitative analysis are covered by Koenig [170], in particular regarding theory and application of FTIR to the characterisation of polymers. Hummel [171] has also discussed quantitative IR spectroscopic analysis of additives. 

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