LCST in poly(N-isopropylacrylamide) copolymers: high resolution proton NMR investigations

Deshmukh, Mandar V.; Vaidya, Alankar A.; Kulkarni, M. G.; Rajamohanan, P. R.; Ganapathy, S.

doi:10.1016/s0032-3861(00)00174-9

Cited by 82 publications

(65 citation statements)

References 23 publications

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“…At pH 1.2 the sharp water signal, independent of copolymer composition, constantly moves to higher field with increasing temperature. This effect has already been reported [27,28] and was attributed to the temperature dependence of hydrogen bonding among water molecules. The broad peak, on the contrary, does not show such a temperature dependence, but strongly depends on the copolymer composition.…”

Section: H Wideline Spectroscopysupporting

confidence: 69%

Advanced ¹H Solid‐State NMR Spectroscopy on Hydrogels, 2

Díez-Peña

Quijada‐Garrido

Barrales‐Rienda

et al. 2004

Macro Chemistry & Physics

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Summary: Advanced 1H solid‐state NMR methods are applied for studying the hydrogen bond formation occurring in polymer hydrogels based on N‐isopropylacrylamide (NIPAAm) and methacrylic acid (MAA). For P(NIPAAm‐co‐MAA) copolymers collapsed at low pH, two populations of water can be distinguished in 1H magic‐angle spinning (MAS) NMR spectra, one of which is probably situated near stable hydrogen‐bonded regions, while the other behaves similarly to free water. The pH‐induced polymer collapse can be followed in detail using 2D 1H‐1H double quantum (DQ) MAS NMR experiments on dried samples. For collapsed copolymers as well as interpenetrating polymer networks, the appearance of characteristic signals shows that hydrogen bonding takes place between NIPAAm and MMA monomers. The temperature dependence of the DQ spectra indicates that acid‐amide hydrogen bonds formed between both comonomers are more stable than the acid‐acid hydrogen bonds formed among MAA moieties alone. Correspondingly, by analyzing 1H‐1H DQ sideband patterns, a relatively short distance of 270 pm is found for the NIPAAm‐MMA hydrogen bond. Finally, the pH dependence of the DQ spectra demonstrates that hydrogen bonding phenomena are directly related to the polymer collapse. magnified image

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Section: H Wideline Spectroscopysupporting

confidence: 69%

Advanced ¹H Solid‐State NMR Spectroscopy on Hydrogels, 2

Díez-Peña

Quijada‐Garrido

Barrales‐Rienda

et al. 2004

Macro Chemistry & Physics

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“…[53] 1 H and 19 F NMR spectra were recorded at various temperatures below and above LCST. Caused by the fact that solids do not contribute to the NMR signals when measured in the solution mode, the intensity of proton signals can be used to monitor the aggregation and phase separation behavior of polymers in solvents.…”

Section: H-and 19 F Nmr Studies Of the Thermoresponsive Behaviormentioning

confidence: 99%

“…The assignment of the protons is provided in detail in ref. [53,54] Both polymers P 28 N 3 and P 28 F 9 have an LCST at the temperature where the intensity of all protons decreases sharply. This decrease appears for P 28 N 3 between 51 to 52 8C as can be seen in Figure 8(a).…”

Section: H-and 19 F Nmr Studies Of the Thermoresponsive Behaviormentioning

confidence: 99%

Aggregation Behavior of Poly(N‐isopropylacrylamide) Semitelechelics with a Perfluoroalkyl Segment in Water^a

Kyeremateng

Fuchise

et al. 2009

Macro Chemistry & Physics

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Two hydrophobically modified PNIPAM semitelechelics PxF9 were prepared by “clicking” PNIPAM containing an azide endgroup (PxN3) with nonadecafluoro‐1‐decyl hex‐5‐ynoate (F9). Micelles of PxF9 in water with a core of F9‐segments and a PNIPAM corona were detected by dynamic light scattering and by 1H and 19F NMR spectroscopy below the LCST. Just below the LCST, the PNIPAM chains start to collapse onto the F9 core followed by aggregation of several collapsed micelles to large particles in the range of ≈110 nm. The F9 segments shifted the LCST to lower temperatures when comparing PxN3 with PxF9. The existence of micelles in PxF9 solutions also improved the reversibility of the LCST behavior as measured by DSC.

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“…This effect has already been reported by some authors. [40,41] In Figure 1 b, the spectral region of the water resonance is magnified. Some overlapped peaks appear that could correspond to different populations of water in the gel.…”

Section: Hydrogel Mobility Proton Wideline Spectroscopymentioning

confidence: 99%

NMR Studies of the Structure and Dynamics of Polymer Gels Based onN-Isopropylacrylamide (NiPAAm) and Methacrylic Acid (MAA)

Díez-Peña

Quijada‐Garrido

Barrales‐Rienda

et al. 2002

Macromol. Chem. Phys.

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LCST in poly(N-isopropylacrylamide) copolymers: high resolution proton NMR investigations

Cited by 82 publications

References 23 publications

Advanced ¹H Solid‐State NMR Spectroscopy on Hydrogels, 2

Advanced ¹H Solid‐State NMR Spectroscopy on Hydrogels, 2

Aggregation Behavior of Poly(N‐isopropylacrylamide) Semitelechelics with a Perfluoroalkyl Segment in Water^a

NMR Studies of the Structure and Dynamics of Polymer Gels Based onN-Isopropylacrylamide (NiPAAm) and Methacrylic Acid (MAA)

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LCST in poly(N-isopropylacrylamide) copolymers: high resolution proton NMR investigations

Cited by 82 publications

References 23 publications

Advanced 1H Solid‐State NMR Spectroscopy on Hydrogels, 2

Advanced 1H Solid‐State NMR Spectroscopy on Hydrogels, 2

Aggregation Behavior of Poly(N‐isopropylacrylamide) Semitelechelics with a Perfluoroalkyl Segment in Watera

NMR Studies of the Structure and Dynamics of Polymer Gels Based onN-Isopropylacrylamide (NiPAAm) and Methacrylic Acid (MAA)

Contact Info

Product

Resources

About

Advanced ¹H Solid‐State NMR Spectroscopy on Hydrogels, 2

Advanced ¹H Solid‐State NMR Spectroscopy on Hydrogels, 2

Aggregation Behavior of Poly(N‐isopropylacrylamide) Semitelechelics with a Perfluoroalkyl Segment in Water^a