Analysis of composite nanofibrous layers by confocal Raman microscopy

A method for the determination of nanofibrous mats chemical composition based on Raman spectroscopy and singular value decomposition is presented. Two different composite samples – a simultaneously spun and a layer-by-layer sample – consisting of polycaprolactone and poly(ethylene) oxide were prepared by electrospinning. Using Raman mapping, we were able to determine the chemical composition in various local areas within each sample, and to distinguish and image substantial changes in the distribution of the polymers caused by various preparation parameters. The ratio between both polymers was expressed as the relative fraction of the particular chemical compound. The results were validated by the Fourier transform infrared spectroscopy. The presence of two different substances in the nanofibrous mats was also proved by scanning electron microscopy. Confocal micro-Raman spectroscopy with its chemical sensitivity and spatial resolution may be used to identify inhomogeneities in the nanofibrous materials and could be of great help in the optimization of the electrospinning process.