Relating the dynamics of hydrated poly(vinyl pyrrolidone) to the dynamics of highly asymmetric mixtures and polymer blends

Sasaki, Kaito; Takatsuka, Masanobu; Shinyashiki, Naoki; Ngai, K. L.

doi:10.1016/j.molliq.2021.115907

Cited by 9 publications

(6 citation statements)

References 82 publications

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“…The derivatives, dε′(f)/df, are well known for approaching the dielectric loss spectra of relaxation processes. 64,65 The enlarged differential real part of the p-process is shown in Figure 11. At several temperatures, a tiny peak can be visible in the enlarged differential real part.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…We performed the frequency derivatives of ε′( f ) at all temperatures in order to clearly distinguish the low-frequency process suggested by this small step in the real part ε′( f ) of 10 wt % PNIPAM aqueous suspension at roughly 3 MHz. The derivatives, dε′( f )/d f , are well known for approaching the dielectric loss spectra of relaxation processes. , The enlarged differential real part of the p-process is shown in Figure . At several temperatures, a tiny peak can be visible in the enlarged differential real part.…”

Section: Resultsmentioning

confidence: 99%

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Dynamics of the Poly(N-Isopropylacrylamide) Microgel Aqueous Suspension Investigated by Dielectric Relaxation Spectroscopy

et al. 2022

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Free-radical precipitation polymerization was used to make non-ionic poly(N-isopropylacrylamide) (PNIPAM) microgel particles. On the synthesized PNIPAM microgel particles, a dynamic light scattering experiment was performed, and hydrodynamic radii were determined to be roughly 240 and 125 nm for temperatures of 298 and 313 K, respectively. Dielectric experiments were carried out on a 10 wt % PNIPAM microgel aqueous suspension at temperatures extending from 288 to 323 K, including volume phase transition temperature (VPTT) at 305 K in the frequency range of 40 Hz to 50 GHz. At frequencies of about 3−5 MHz and 16−18 GHz, two distinct relaxation processes were detected, in addition to electrode polarization and the contribution of dc conductivity. The local chain motion of PNIPAM (p-process) and the average relaxation mode of water located at the bulk solution and also within the microgel (w-process) are assumed to be the origins of the two relaxation processes. Furthermore, based on the idea of two kinds of water models, contributions of each of the two kinds of water, both free water outside the microgel (w1, with its relaxation time of τ w1 ) and confined water within the microgel (w2, with its relaxation time of τ w2 ), to the high-frequency relaxation spectrum were evaluated. The τ w2 is only 2−2.7 times larger than τ w1 above VPTT. This means that rotational motion of water molecules is not significantly constrained inside the microgel particle even above VPTT. The NMR rotational correlation time τ c , which is comparable to the dielectric relaxation time, was estimated using Bloembergen−Purcell−Pound (BPP) theory. The 3τ c value for the microgel suspension obeys BPP theory only up to VPTT; above that, due to anisotropy and/or loss of translational mobility of water induced by microgel shrinkage, precondition of BPP theory is broken. Furthermore, we obtained the concentration of PNIPAM in microgel particles using both the relaxation times and relaxation strengths of w1 and w2 above and below VPTT. Below VPTT, the p-process locates at the MHz region, and it shifts toward the lower-frequency side above VPTT due to the hindrance by microgel structural changes. The dynamics of the polymer and water inside and outside microgel particles in the solution bulk are observed simultaneously by the same physical quantities through the volume phase transition.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Dynamics of the Poly(N-Isopropylacrylamide) Microgel Aqueous Suspension Investigated by Dielectric Relaxation Spectroscopy

et al. 2022

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“…Recently, it was suggested in the literature that the dynamics of protein-water [60] or polymer-water [61] mixtures have similar characteristics to those of highly asymmetric mixtures of two glass-formers or polymers. These systems, called HAM (highly asymmetric mixtures), were intensely studied in the literature [62][63][64][65].…”

Section: Comparison Between Highly Asymmetric Mixtures Of Liquids And...mentioning

confidence: 99%

Influence of ice formation on the dynamic and thermodynamic properties of aqueous solutions

2022

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“…PVP was studied in pure and hydrated forms for various molecular weights. [35][36][37][38][39][40][41][42][43][44][45][46] PVP-based amorphous solid dispersions featuring pharmaceuticals such as nifedipine, 47,48 indomethacin, [49][50][51] and others were also investigated. 52 Another area of research, which is particularly relevant for energy storage technologies, is the transport of penetrants that act as electric charge carriers in polymer matrices.…”

Section: Introductionmentioning

confidence: 99%

Relaxation and diffusion of an ionic plasticizer in amorphous poly(vinylpyrrolidone)

Röwekamp,

Moch,

Seren

et al. 2024

Phys. Chem. Chem. Phys.

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Relating the dynamics of hydrated poly(vinyl pyrrolidone) to the dynamics of highly asymmetric mixtures and polymer blends

Cited by 9 publications

References 82 publications

Dynamics of the Poly(N-Isopropylacrylamide) Microgel Aqueous Suspension Investigated by Dielectric Relaxation Spectroscopy

Dynamics of the Poly(N-Isopropylacrylamide) Microgel Aqueous Suspension Investigated by Dielectric Relaxation Spectroscopy

Influence of ice formation on the dynamic and thermodynamic properties of aqueous solutions

Relaxation and diffusion of an ionic plasticizer in amorphous poly(vinylpyrrolidone)

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