Growth of Polymer Crystals

Tashiro, Kohji

doi:10.1002/9781118541838.ch5

Cited by 11 publications

(9 citation statements)

References 112 publications

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“…By comparing the DSC curve of PEG-2NH 2 with that of D230, it becomes evident that D230 does not crystallize at low temperatures but merely undergoes a glass transition, while PEG-2NH 2 experiences significant crystallization. According to Figure e, PEG-2NH 2 exhibits prominent crystallization peaks, where the double peaks are indicative of postcrystallization . It follows that, in contrast to linear PEG-2NH 2 , branched D230 molecules are difficult to stack together to form crystals, reflecting an unfavorable molecular packing.…”

Section: Resultsmentioning

confidence: 95%

Noncrystalline Hybrid Lead Halides with Liquid-Polymer Characteristics

et al. 2022

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Hybrid lead halide (HLH) semiconductors, particularly those featuring perovskite and its derivative structures, have been popular materials with many promising optoelectronic applications. In general, HLHs are predominantly crystalline solids, whether they are bulk single crystals, microcrystals, or nanocrystals. This paper shows that when some short-chain Jeffamine, a widely used polyetheramine, is used as the organic species, the resultant HLH would become noncrystalline with unusual liquid-polymer-like characteristics. In this material, Jeffamine ammoniums and lead halide octahedron frameworks are both arranged amorphously, while its optical properties are similar to those of crystalline HLHs. In contrast to conventional organic species, Jeffamine exhibits a disordered molecular packing, which is believed to account for the peculiar characteristics of the HLH products. Through A-site engineering with Jeffamine, even classic lead halide perovskites such as CsPbBr3 can acquire partial noncrystallinity and transform into a liquid-polymer-like form. This discovery demonstrates that Jeffamine as a novel organic species would confer liquid-polymer properties to the products, which may provide a strategy to transform HLH materials and classic halide perovskites into special “liquid semiconductors”, thereby potentially enabling new processing techniques and new designs of soft electronics.

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Section: Resultsmentioning

confidence: 95%

Noncrystalline Hybrid Lead Halides with Liquid-Polymer Characteristics

et al. 2022

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“…The ionic conductivity of solid polymer electrolytes is severely affected by the large crystalline domains present in the polymer chains [ 16 ]. Crystallinity is a fundamental characteristic of polymeric systems which defines mechanical, thermal, optical, electronic, and transport properties [ 17 , 18 , 19 ]. A high crystallinity limits the movement of lithium ions [ 20 , 21 ] and, hence, enhances the ionic conductivity of SPEs.…”

Section: Introductionmentioning

confidence: 99%

Improved Performance of Solid Polymer Electrolyte for Lithium-Metal Batteries via Hot Press Rolling

et al. 2022

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Solid-state batteries (SSBs) are gaining attention as they promise to provide better safety and a higher energy density than conventional liquid electrolyte batteries. Solid polymer electrolytes (SPEs) are promising candidates due to their flexibility providing better interfacial contact between electrodes and the electrolyte. However, SPEs exhibit very low ionic conductivity at ambient temperatures, which prevents their practical use in batteries. Herein, a simple and effective technique of hot press rolling is demonstrated to improve ionic conductivity and, hence, the performance of polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP)-based solid polymer electrolyte. Applying hot press rolling to the electrolyte membrane induced structural changes in the grain boundaries, which resulted in a reduction in the crystallinity of the material and, hence, an increase in the amorphous phase of the material, which eased the movement of the lithium ions within the material. This technique also improved the surface of the membrane, making it homogeneous and smoother, which resulted in better interfacial contact between the electrodes and electrolyte. Electrochemical tests were carried out on electrolyte membranes treated with and without hot press rolling to evaluate the effect of the treatment. The hot pressed electrolyte membrane showed significant improvements in its ionic conductivity and transference number. The cycling performance of the LFP/Li batteries using a hot press rolled electrolyte was also evaluated, which gave a specific discharge capacity of 134 mAh/g at 0.1 C. These results demonstrate that hot press rolling can have a significant effect on the electrochemical performance of solid polymer electrolytes.

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“…The crystallization behavior of a crystalline polymer is indispensable information for the development of polymer materials with excellent physical properties [1,2,3,4,5,6,7,8]. The hierarchical structure of a crystalline polymer must be clarified from such various structural points of view, such as chain conformation, packing structure of chains in the crystal lattice, stacking structure of lamellae, and inner structure of a spherulite.…”

Section: Introductionmentioning

confidence: 99%

“…We have to quote the words of Dr. Keller [22], who warned of the easy generalization of chain folding mechanisms in the controversial discussions of the 1970s: “We have to notice that the discussion has been made only for polyethylene”. Besides, most of the papers only analyzed the WAXD and/or SAXS data to reveal the formation of the crystalline lattice, the stacked lamellar structure, etc., but the molecular chain state in the much earlier stages of crystallization has not yet been revealed on the experimental side [1,2,3,4,5,6,7,8]. For this purpose, the vibrational spectroscopy plays an important and indispensable role.…”

Section: Introductionmentioning

confidence: 99%

Structural Evolution Mechanism of Crystalline Polymers in the Isothermal Melt-Crystallization Process: A Proposition Based on Simultaneous WAXD/SAXS/FTIR Measurements

Tashiro

Yamamoto

2019

Polymers

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Time-resolved simultaneous measurements of wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) (and FTIR spectra) were performed for various kinds of crystalline polymers in isothermal melt-crystallization processes, from which the common features of the structural evolution process as well as the different behaviors intrinsic to the individual polymer species were extracted. The polymers targeted here were polyethylene, isotactic polypropylene, polyoxymethylene, aliphatic nylon, vinylidene fluoride copolymer, trans-polyisoprene, and poly(alkylene terephthalate). A universal concept of the microscopically viewed structural evolution process in isothermal crystallization may be described as follows: (i) the small domains composed of locally regular but more or less disordered helical chain segments are created in the melt (this important information was obtained by the IR spectral data analysis); (ii) these domains grow larger as the length and number of more regular helical segments increase with time; (iii) the correlation among the domains becomes stronger and they approach each other; and (iv) they merge into the stacked lamellar structure consisting of the regularly arranged crystalline lattices. The inner structure of the domains is different depending on the polymer species, as known from the IR spectral data

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Growth of Polymer Crystals

Cited by 11 publications

References 112 publications

Noncrystalline Hybrid Lead Halides with Liquid-Polymer Characteristics

Noncrystalline Hybrid Lead Halides with Liquid-Polymer Characteristics

Improved Performance of Solid Polymer Electrolyte for Lithium-Metal Batteries via Hot Press Rolling

Structural Evolution Mechanism of Crystalline Polymers in the Isothermal Melt-Crystallization Process: A Proposition Based on Simultaneous WAXD/SAXS/FTIR Measurements

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