Network structure of swollen iodine-doped poly(vinyl alcohol) amorphous domain as characterized by low field NMR

Li, Yahui; Yang, Junsheng; Cheng, H. S.; Cai, Linkun; Yao, Ke; Xia, Zhijie; Zhang, Qianlei; Wang, Daoliang; Chen, Wei

doi:10.1039/d1sm00988e

Cited by 8 publications

(26 citation statements)

References 48 publications

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“…It suggests that the mechanical training enhances the hydrogen bonding among PVA chains, increases the crystallinity of multi‐scale fibrils, and lowers the mobility of the anisotropic network. [ 29 ] Furthermore, the amorphous domain and bound water‐related T 2 is slower after mechanical training. Although previous reports show that the overall water content slightly decreases after the mechanical training, [ 28,30 ] our LF NMR results indicate that the mechanical training strengthens hydrogen bonds between PVA chains but weakens those between PVA chains and water molecules.…”

Section: Resultsmentioning

confidence: 99%

Anti‐Fatigue and Highly Conductive Thermocells for Continuous Electricity Generation

Lei

Gao

Zhu

et al. 2022

Adv Funct Materials

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The integration of wearable technologies with the human body requires power supplies that are mechanically compatible and able to continuously generate electricity like biological systems. Distinct from existing batteries relying on periodic recharging, thermocells added with thermogalvanic ions are a promising candidate because they enable continuous electricity generation through redox reactions driven by ubiquitous waste heat. However, challenges remain in mechanical adaptability, fatigue resistance, and ion conduction, severely limiting thermocells’ sustainability and lifespan in practical applications. Herein, bionic mechanical training is applied to develop anti‐fatigue and highly conductive thermocells with hierarchical fibrils and aligned nanochannels. It achieves simultaneous enhancements in mechanical performance and output power density. Compared with existing quasi‐solid thermocells with disordered nano‐networks, there are ≈1790‐fold and 5‐fold increases in the mechanical toughness and ionic conductivity, respectively. The stretchability can accommodate the human body's deformation, and the power density is comparable to that of state‐of‐the‐art quasi‐solid thermocells. Moreover, this is the first demonstration of an anti‐fatigue thermocell with a threshold of 2500 J m−2, which is comparable to that of natural muscles and enables it to take full advantage of the continuous energy conversion mode.

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Section: Resultsmentioning

confidence: 99%

Anti‐Fatigue and Highly Conductive Thermocells for Continuous Electricity Generation

Lei

Gao

Zhu

et al. 2022

Adv Funct Materials

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“…À complexes can only form in the noncrystalline domain; (ii) for intermediate iodine concentrations of 0.1-1 M, in addition to the pure PVA crystal, a new crystal of PVA-I 3 À complex I is formed in the dyeing film; (iii) for high iodine concentrations of 1-5 M, the PVA-I 3 À complex II is formed in the crystalline domain. 32 Based on these results, four iodinated PVA films with different PVA-iodine complexes were prepared in the current study. The 2D WAXS patterns and the corresponding 1D integrated curves of these samples are shown in Fig.…”

Section: Types Of Pva-iodine Complexesmentioning

confidence: 99%

“…This is consistent with that obtained using the low-field NMR method. 32 Based on the large difference in the 13 C T 1 relaxation time of these three phases, several 13 C CP/MAS spectra with different T 1 filter times were chosen, as shown in Fig. 3(c).…”

Section: Characterization Of Three-phase Structuresmentioning

confidence: 99%

“…By changing the iodine concentration, the FWHM of C(H)(I) drops down only when PVA-I 3 À complex II is formed (5 M), which is considerably consistent with the unchanged crosslinking points in the amorphous domain before the formation of PVA-I 3 À complex II observed by the low-field NMR. 32…”

Section: Characterization Of Three-phase Structuresmentioning

confidence: 99%

“…Considering the chain conformation difference in the amorphous and interphase domains, the PVA-iodine complexes that form along tie chains in the interphase are more stable. 32 The same method to selectively detect the three-phase structure was applied to the highly oriented film (0 M-5). Since stretching can significantly reduce the conformational entropy, resulting in an accelerated nucleation rate, [47][48][49] the conformational differences in the three phases will be reduced in highly oriented samples.…”

Section: Macro-extension Vs Micro-extensionmentioning

confidence: 99%

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Evidence for complexation-induced micro-extension of poly(vinyl alcohol) chains in interphase and amorphous domains from solid-state NMR

Wei

Chen

2022

Soft Matter

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Molecular mobility and morphology change of poly(vinyl alcohol) (PVA) film as induced by plasticizer glycerol

Fei

Cheng

et al. 2023

Journal of Polymer Science

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The addition of small molecular plasticizer is an efficient strategy to increase the process ability and macroscopic performance of poly(vinyl alcohol) (PVA). However, how the plasticizer influences the chain dynamics and morphology deserves further investigation. In this work, the PVA film with varying glycerol addition levels was used as the model system. The increasing glycerol addition‐level results in the depression of the melting temperature and crystallization temperature, which in line with Flory's theory. The enhanced chain dynamics in the mobile domain was accessed by low‐field NMR, whereas that in the crystalline region remains constant. The domain size as well as the morphology of the mobile phase are accessed by 1H spin‐diffusion NMR. The results indicate the increasing dimensionality of the plasticized PVA film with increasing the addition level of glycerol, where the addition level below 25 wt% leads to the dimensionality of 1D, and higher than 25 wt% results in the dimensionality of 2D. Current results elucidate the critical role of the plasticizer in modulating the dynamics heterogeneity of the plasticized polymer film, which is closely related to the macroscopic performance of the products.

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Network structure of swollen iodine-doped poly(vinyl alcohol) amorphous domain as characterized by low field NMR

Abstract: The network structure in the amorphous domain of swollen iodine-doped poly (vinyl alcohol) (PVA) were systematically investigated by low-field (LF) NMR techniques to reveal the PVA-iodine complex formation mechanism. Three...

Cited by 8 publications

References 48 publications

Anti‐Fatigue and Highly Conductive Thermocells for Continuous Electricity Generation

Anti‐Fatigue and Highly Conductive Thermocells for Continuous Electricity Generation

Evidence for complexation-induced micro-extension of poly(vinyl alcohol) chains in interphase and amorphous domains from solid-state NMR

Molecular mobility and morphology change of poly(vinyl alcohol) (PVA) film as induced by plasticizer glycerol

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