Second order multivariate curve resolution of Fourier transform infrared spectroscopic data of the photo-induced crosslinking of thymine functionalized polymers

Fluorescence spectroscopy and multivariate analysis as a greener monitoring tool: characterization of the curing kinetics of bioinspired polymers

“…Making use of these results and Equation (2) (Section 2), it is possible to identify the kinetics profiles of the species involved in the curing reaction ( Figure 5). Interestingly, the kinetics profiles are in agreement with reported results for VBT-VBA copolymers (16,18), suggesting that the curing process is only VBT-dependent. On the other hand, for each copolymer composition, the VPS species remains constant throughout the entire cross-linking reaction, while as the concentration of the VPS interferent augments, the chemometric resolution gets worse ( Figure 5(e)).…”

“…Regarding the spectral features of the excitation and emission profiles assigned to VBT (blue line in Figure 6(c)), reported data for thymine fluorescence (20) indicate a comparable emission maximum at 400 nm (λ exc = 295 nm), even if no quantitative evaluation of such similarity is possible. Finally, the refolded spectral profiles designed for the species generated in the curing reaction are in agreement with previously reported data (16,18), allowing us to make a suggestion of the species involved in the curing process (see Scheme 1).…”

“…Thymine has a fluorescence emission maximum at 410 nm when the excitation wavelength range is set between 290-340 nm (20); therefore it is likely that the observed signal corresponds to thymine groups in VBT copolymers. However, as irradiation time increases, thymine moieties get cross-linked to generate the cyclobutane ring (16,18). This effect cannot be easily observed on the EEFMs at different irradiation times, since only a mild reduction in the signal intensity can be seen, with no substantial changes of the spectra.…”

“…To verify the absence of unreacted monomers, the precipitated polymer was analyzed by 1 H NMR spectroscopy and the typical vinyl group signal at chemical shifts between 5 and 6 ppm was not observed in the spectra. Additionally, elemental analysis was used to confirm copolymer ratios (18).…”

“…Additionally, the authors accomplished the quantification of all species, even in the presence of an interferent compound (18). FT-IR absorption spectra for different irradiation doses and different VBT-VBA copolymer compositions in solid phase were taken using grazing-angle specular-reflectance FT-IR spectroscopy, and the matrices were processed with MCR-ALS algorithm.…”