Real-time Raman spectroscopy was successfully utilized to monitor solvent evaporation and molecular orientation during electrospinning of atactic polystyrene (a-PS). The use of a binary solvent system of N,N-dimethyl formamide (DMF) and tetrahydrofuran (THF) provided a stable, straight jet during the experiment. The prominent Raman bands centered at 866 cm<sup>–1</sup>, 914 cm<sup>–1</sup>, and 1004 cm<sup>–1</sup>, unique to DMF, THF, and a-PS, respectively, were used to monitor solvent concentration changes along the electrospinning jet for two different a-PS solutions. In addition, the changes in relative intensity for the radial skeletal ring vibration of the aromatic group of a-PS at 623 cm<sup>–1</sup> in two different polarization geometries, ZZ and YY, were monitored for orientation information. This study reports the first quantitative vibrational spectroscopic measurement during the electrospinning process. A significant change in concentration and orientation was observed during the process. The changes are explained in relation to the electrospinning process.
Giriprasath Gururajan, Carl B. Giller, Christopher M. Snively, D. Bruce Chase, and John F. Rabolt, "Molecular Orientation Evolution and Solvent Evaporation During Electrospinning of Atactic Polystyrene Using Real-Time Raman Spectroscopy," Appl. Spectrosc. 65, 858-865 (2011)