Application of multivariate analysis of NMR spectra of poly(N-isopropylacrylamide) to assignment of stereostructures and prediction of tacticity distribution

Hirano, Tomohiro; Anmoto, Takuya; Umezawa, Nao; Momose, Hikaru; Katsumoto, Yukiteru; Oshimura, Miyuki; Ute, Koichi

doi:10.1038/pj.2012.61

Cited by 15 publications

(7 citation statements)

References 25 publications

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“…). The tacticity was studied in the range between 41.8 and 42.9 ppm, where the rr , mr , and mm triads are clearly identified, which are associated with the heterotactic sequences …”

Section: Resultsmentioning

confidence: 99%

Lower critical solution temperature sensitivity to structural changes in poly(N‐isopropyl acrylamide) homopolymers

García‐Peñas

Wang

Muñoz‐Bonilla

et al. 2019

J Polym Sci B Polym Phys

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The effect of the molecular weight on the lower critical solution temperature (LCST) has been discussed extensively, where LCST increased with molar mass, decreased or kept constant, which leads to confusion. This work is focused on the preparation of poly(N‐isopropyl acrylamide) homopolymers, obtained in a wide molecular weights range. The LCST behavior is analyzed by calorimetry and rheology, and a deep study of molecular features is carried out for a better knowledge of the influence of various parameters involved on LCST. Finally, the molecular weight trend is observed, and its influence on LCST is compared with the effect of other parameters as polymer concentration in water, end‐group effect, and tacticity. It is observed that other parameters such tacticity and end‐group effect will affect the LCST behavior over molecular weight, if this one is not high enough. Furthermore, the study of the LCST ranges will be a useful tool for analyzing the molecular weight trends. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 1386–1393

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“…). The tacticity was studied in the range between 41.8 and 42.9 ppm, where the rr , mr , and mm triads are clearly identified, which are associated with the heterotactic sequences …”

Section: Resultsmentioning

confidence: 99%

Lower critical solution temperature sensitivity to structural changes in poly(N‐isopropyl acrylamide) homopolymers

García‐Peñas

Wang

Muñoz‐Bonilla

et al. 2019

J Polym Sci B Polym Phys

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“…Two PNIPAM samples with different racemic (r) diad, r-57 and r-66, were synthesized in toluene at -60 °C in the presence of methanol and 3-methyl-3-pentanol, respectively, as reported previously [49]. The tacticities of the samples were determined in DMSO-d6 solutions by 13 C solution NMR using JEOL ECX 400 MHz NMR spectrometer [50,51]. The samples were named according to the r-diad level as calculated from the triad intensities with the equation r = rr + mr/2.…”

Section: Experimental Samplesmentioning

confidence: 99%

NMR studies of water dynamics during sol-to-gel transition of poly (N-isopropylacrylamide) in concentrated aqueous solution

Kametani

Sekine

Ohkubo

et al. 2017

Polymer

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The focus of this work was on the significant changes in the water dynamics of aqueous poly(N-isopropylacrylamide) (PNIPAM) solution during sol-to-gel transition. Through the use of NMR (particularly two-dimensional 2 H NMR T 1-T 2 relaxation) and rheology, we were able to show that below 34 o C fast exchange occurs among free water and water molecules adsorbed on the surface of PNIPAM molecules. At 34 o C, PNIPAM becomes aggregated; most of the water molecules are trapped in the PNIPAM aggregates, where water molecules with different dynamics are found. Above 34 o C, PNIPAM molecules aggregate further to form a gel network; the free bulk water then becomes dominant at this stage. On the basis of these observations, a model where water molecules interact with PNIPAM in different ways during the transition was proposed. We believe that our experimental approach provides new information and fresh perspectives on the sol-to-gel transition of PNIPAM.

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“…In Figure , the signal of the C(c) in the homopolymer, attributed by the HSQC spectrum, was found in the range between 41 and 43 ppm, and the C(d) signals at about 33 and 37 ppm. Both carbon groups show stereochemical sensitivity, the C(c) carbon resonances have been attributed by Hirano et al to the syndiotactic triad rr = 42.63 ppm, the heterotactic triad rm = 42.3 ppm, and the isotactic triad mm = 41.6 ppm.…”

Section: Resultsmentioning

confidence: 90%

Poly(ionic liquid)s derived from 3-octyl-1-vinylimidazolium bromide andN-isopropylacrylamide with tunable properties

Illescas

Casu

Alzari

et al. 2014

J. Polym. Sci. Part A: Polym. Chem.

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A new series of linear and crosslinked copolymers, obtained from 3-octyl-1-vinylimidazolium bromide (VImBr) and N-isopropylacrylamide (NIPAAm), were prepared by radical polymerization. Namely, VImBr was synthesized from 1-bromooctane and an ionic liquid such as 1-vinylimidazole. NIPAAm was used because it gives raise to well known thermoresponsive (co-)polymers. The copolymers were thoroughly characterized by means of 1 H NMR and 13 C NMR spectroscopies. Besides, differential scanning calorimetry, Fourier transform infrared spectroscopy, and scanning electron microscopy were also used. Moreover, the swelling behavior and the thermoresponsive properties of the corresponding hydrogels were studied. It was found that the VImBr incorporation into the copolymers does have a dramatic influence on both the thermal properties of the dried materials and the lower critical solution temperature of the corresponding hydrogels. In detail, the glass transition temperature was dependent on the monomer ratios, and ranged from 5 to 155 C. Analogously, the lower critical solution temperature of the resulting hydrogels ranged from less than 10 up to 38 C, thus including the physiological temperature. NMR spectroscopies, which were performed on the linear polymers, indicated that the monomers exhibit an alternating tendency resulting in a microstructure in which blocks are not present, at least when the two monomers are in equimolar amounts.

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Application of multivariate analysis of NMR spectra of poly(N-isopropylacrylamide) to assignment of stereostructures and prediction of tacticity distribution

Cited by 15 publications

References 25 publications

Lower critical solution temperature sensitivity to structural changes in poly(N‐isopropyl acrylamide) homopolymers

Lower critical solution temperature sensitivity to structural changes in poly(N‐isopropyl acrylamide) homopolymers

NMR studies of water dynamics during sol-to-gel transition of poly (N-isopropylacrylamide) in concentrated aqueous solution

Poly(ionic liquid)s derived from 3-octyl-1-vinylimidazolium bromide andN-isopropylacrylamide with tunable properties

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