Real‐time monitoring of ring‐opening polymerization of tetrahydrofuran via in situ Fourier Transform Infrared Spectroscopy

Abstract

The polymerization of tetrahydrofuran (THF) was carried out in CH2Cl2 by using phosphotungstic heteropolyacid as initiator and epichlorohydrin as promoter. This cationic ring‐opening polymerization process was monitored by in situ mid‐infrared spectroscopy system (ReactIR) to further study the thermodynamics and kinetics of THF polymerization. It was observed that the sharp infrared peak of COC stretching vibrations will shift from about 1068 to 1109 cm−1 in THF ring‐opening step. The changes in absorbance intensity of the two characteristic peaks were used for determining instantaneous concentration of linear polymer and ring monomer. The experimental results demonstrated that the kinetics of THF polymerization proved to be typically first‐order. Thermodynamic parameters were determined from the temperature dependence of the monomer equilibrium concentration [M]e over the range from −5 to 25°C. The values of kapp were obtained via the plots of ln{([M]0−[M]e)/([M]t−[M]e)} vs reaction time, for polymerization under specific conditions. The apparent activation energy (Ea) and frequency (A) were determined from the Arrhenius plot of kapp vs. T−1. Besides, the in situ kinetic investigation revealed that more chain‐transfer occurred at higher temperatures, leading to a reduction in propagation species concentration and a deviation from first‐order propagation at the later stage of polymerization. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40503.

Carboxylic acid-capped ruthenium nanoparticles: experimental and theoretical case study with ethanoic acid

“…THF could also be indirectly responsible for the weak signal close to 1950 cm -1 , that may be attributed to a carbonyl group (CO) derived from THF degradation as previously observed with other ruthenium NPs (incidentally, Ru-H stretching modes are calculated to lie in the same domain frequency). 8 The last unassigned peak, b, could be attributed to polytetrahydrofuran (PTHF), 45 owing to a transitory adsorption of THF followed by ring-opening polymerization process. To conclude on this part, the results point out that the ligands surrounding the ruthenium NPs are not under the carboxylic acid form and confirm the deprotonation of the ethanoic acid upon coordination, now observed as a carboxylate by IR, as precedently by NMR.…”

In situ monitoring of additives during CO2gas hydrate formation

“…For THF, the pronounced asymmetric C-O-C vibration n asC-O-C THF is evident (centered at 1041 cm À1 in H 2 O and 1039 cm À1 in D 2 O) in the sample spectra. 38 In the region between 1270 and 1100 cm À1 absorption features of the used poly(tetrauoroethylene) (PTFE) ferrules for sealing the IR ber into the feed-through of the pressure vessel are evident. In the D 2 O experiment, these are being convoluted by the DOD absorption feature (n 2(DOD) ).…”

Heteropolycompounds as catalysts for biomass product transformations

“…Shi et al 116 showed that by using a combination of copper nitrate with PMo it was possible to achieve a maleic acid yield of 49.2% with a selectivity value of 51.7%, at 95. . In several research studies, these traditional initiators were replaced by heteropolyacids [121][122][123][124][125][126][127][128][129][130][131][132][133] . Heteropolyacids were also used as catalysts in a number of protocols.…”