FTIR studies of conformational energies of poly(acrylic acid) in cast films

Abstract

Fourier transform infrared (FTIR) spectroscopic measurements have been undertaken to estimate the conformational energies of poly(acrylic acid) (PAA) cast films in the temperature range of 40–130°C. The temperature dependence of the IR spectra in the C=O stretching region has been analyzed to yield the side‐chain and backbone conformational energies. The estimated energies are close to those previously obtained by polarized Raman spectroscopic measurements for PAA solutions. Combining the FTIR value of conformational energy with the simplified rotational isomeric state (RIS) model proposed in the Raman analysis provides a persistence length in accordance with earlier SAXS experiments. The data also agree with the Gibbs‐DiMarzio predictions, further substantiating the validity of the analysis. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys, 35: 507–515, 1997

Heterodyne-detected sum frequency generation spectroscopy of polyacrylic acid at the air/water-interface

“…Two negative bands appear at E2875 cm À1 and E2935 cm À1 and a weaker positive band is observed at E2975 cm À1 . The presence of three resonances in the CH region at these frequencies is in agreement with previous IR and Raman studies of PAA 22 and previous SFG work of partially hydrated polyacrylamide. 9 In line with these previous studies we assign the negative bands at E2875 cm À1 and E2935 cm À1 to the stretch vibration of the methine group (n CH ) and the symmetric stretch of the methylene group (n CH 2 ,SS ), respectively, and the positive band at E2975 cm À1 to the asymmetric stretch of the methylene group (n CH 2 ,AS ).…”

Crosslinking Effect on Thermal Conductivity of Electrospun Poly(acrylic acid) Nanofibers

“…The subtraction was made after the normalization with the band at 1451 cm −1 , as mentioned above. In the difference spectra, the well-separated anhydride peak at 1802 cm −1 and a significant change of the relative intensity ratios of the bands at 1757 and 1698 cm −1 were observed and are in accordance with the findings of a previous study [33], indicating that the crosslinking modified the polymer backbones of PAA NFs from trans to gauche conformation. As shown in Figure 6d, the I 1757 / I 1698 values of XLPAA NFs, which were obtained from the directly measured spectra, were much higher than those of the as-spun PAA NFs, resulting from the transition of molecular chain backbones from trans to gauche states.…”

Cellulose nanocrystal-filled poly(acrylic acid) nanocomposite fibrous membranes

“…For the pure PAA fibers, heating did not alter the absorbance of the carboxylic carbonyl peak at 1708 cm −1 which was expected with the absence of esterification. The appearance of peaks at 1801 and 1045 cm −1 for the heated PAA fibers indicated the formation of anhydride groups, similar to a previous observation [26]. The unchanged solubility of the heated PAA suggests anhydrides formed to be mainly intramolecular.…”

“…The FTIR spectra of all as-spun 4/20 PAA/CNC nanocomposite fibers (figure 7) showed broad peaks in the 3650-3000 cm −1 range, characteristic of cellulose O-H stretching and the 2933 cm −1 peak likely due to C-H stretching vibrations (figure 7 diagram (A)). The O-H peak broadened with increasing CNC contents in PAA/CNC nanocomposite fibers and appeared to reflect the strength of the hydrogen bonding, similar to the report on PAA cast films [26]. Both pure PAA and as-spun PAA/CNC nanocomposite fibers showed a broad carboxyl carbonyl of PAA at 1708 cm −1 (figures 7(a)-(c) in diagram (B)).…”