Uv–vis spectral characteristics of para-aramid fiber deprotonation products in KOH/DMSO system and their applications.

[Display omitted] • The deprotonation of PPTA forms binary products (PPTA^- and PPTA^2-) in DMSO/KOH medium. • Both PPTA^- and PPTA^2- have a strong absorption in UV/visible wavelength range. • Two characteristic wavelengths (360 and 400 nm) and their coefficients are defined, from which the charge content of PPTA^- and PPTA^2- can be determined. • This work provides a simple and efficient quantitative tool to be used in the exploration of ANFs preparation process. This paper reported a spectroscopic method for quantifying the charge content (C T) during para -aramid fiber (PPTA) deprotonation in KOH/DMSO system. The results showed that there were two deprotonation products, i.e., PPTA^- and PPTA^2- that had spectral absorption at UV/visible wavelength range. It was found that 360 nm was an isosbestic absorption point of PPTA^- and PPTA^2-, while the absorption at 400 nm was only contributed by PPTA^2-. Based on the spectral information, the charge absorption coefficients of PPTA^- and PPTA^2- at the characteristic wavelengths of interest (i.e., k 336 PPT A - , k 360 PPT A - and k 400 PPT A 2 - ) were calculated, and an equation for quantifying the total charge content was also generated. The present method could provide an efficient quantification tool for monitoring the degree of deprotonation reaction of PPTA in the DMSO/KOH system in the aramid nanofibers related research and application. [ABSTRACT FROM AUTHOR]