New FTIR spectroscopic techniques applied to multicomponent polymer systems

The coupling of an array detector with a spectrometer has opened a new frontier in FTIR spectroscopy-FTIR imaging. The technique is an improvement over FTIR mapping, but suffers from poor signal to noise ratio (SNR) data. We have developed methodologies to increase the SNR of data obtained to enable faster acquisition of images with higher SNR. Geometric and Phase co-addition are suggested as possible strategies that increase SNR of extracted data by a factor of $n$, (n is the number of spatial elements co-added). Pseudo co-addition is shown to improve SNR by ∼45%. MNF transform based noise reduction resulted in a SNR increase of ∼600% without an increase in data collection time. Another study provides processing techniques to enable the spectrometer to be used as a morphological characterization tool with the contrast being provided by inherent differences in chemical structure. A technique to locate the interface without the aid of component specific frequencies was also suggested. Combined, these studies have been helpful in applying the new technique to obtain high fidelity data and images while achieving a spatial resolution of better than 10 μm.; New ideas for the examination of multicomponent polymeric systems using continuous scan FTIR spectroscopy were introduced. The formation of Polymer Dispersed Liquid Crystals (PDLCs) from a homogeneous mixture by photopolymerization was examined in-situ by incorporating a UV lamp into the FTIR spectrometer. The curing kinetics of the neat pre-polymer and its (initially) homogeneous solution with a liquid crystal (LC) were recorded in real time. A novel discovery was that the phase separation could be characterized by scattering and the nematic fraction obtained by characteristic vibrational peaks. Hence, both the physical and chemical formation processes could be quantified in a single experiment. A new process was developed to yield PDLCs with lower mutual component solubility. This mutual solubility in each phase was characterized by FTIR imaging and statistical methods. Long term stability of the formed structures was demonstrated using a contact method experiment.