PWA-diureasils organic–inorganic hybrids. Photochromism and effect of the organic chain length

Obara, P. A.; Sarmento, Víctor Hugo Vitorino; Ribeiro, Sidney J. L.; Nalin, Marcelo; Molina, C.

doi:10.1016/j.optmat.2015.03.054

Cited by 6 publications

(6 citation statements)

References 18 publications

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“…In our material, a similar behaviour was observed, once the repetition of the polymer chain in d-ureasil hybrids is polyoxypropylene (PPO). In d-ureasil hybrid network, socalled class II, the PPO or PEO units can be controlled with different polymer chain length and consequently the bleaching process can be monitored as observed in our previous work [12].…”

Section: Resultsmentioning

confidence: 94%

“…Organic Inorganic Hybrid (OIH) materials containing polyoxometalates (POMs) entrapped have attracted enormous attentions which make them suitable for photochromic applications [1e9]. Phosphotungstic acid (PWA), a Keggin structure, represented by H 3 PW 12 O 40 formula is one of the most important POM used due to its solubility in many solvents, defined size and structure and mainly due to the photoreduction of its W 6þ species under ultraviolet irradiation which promotes change of color [10]. d-ureasil is an interesting class II hybrid material, synthesized by sol gel process, composed by variable polyethylene oxide units covalently bonded to silicon atoms at both sides through urea groups [11].…”

Section: Introductionmentioning

confidence: 99%

“…d-ureasil is an interesting class II hybrid material, synthesized by sol gel process, composed by variable polyethylene oxide units covalently bonded to silicon atoms at both sides through urea groups [11]. The molecular weight of the polymer chain can be tuned which affects the photochromic behavior [12]. Usually, photochromic materials are employed in films deposited on rigid substrate like glass.…”

Section: Introductionmentioning

confidence: 99%

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Photochromic dynamics of organic–inorganic hybrids supported on transparent and flexible recycled PET

et al. 2017

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a b s t r a c tOrganiceinorganic hybrids (OIH) synthesized by sol gel process containing phosphotungstic acid (PWA) entrapped have been attracted much attention for ultraviolet sensitive materials. However, the limitations for practical photochromic application of these materials are the poor interaction with flexible polymer substrates such as Poly(ethyleneterephthalate) (PET) and also photo response under ultraviolet radiation. This paper describes the use of the d-ureasil HOI, based on siliceous network grafted through linkages to both ends of polymer chain containing 2.5 poly(oxyethylene) units with PWA entrapped prepared as films on recycled PET. Films were characterized by IR-ATR, XRD, TG/DTG, UVeVis and Contact angle. XRD patterns showed that both pristine hybrid matrix and those containing PWA are amorphous. IR showed that PWA structure is preserved in the matrix and interactions between them occur by intermolecular forces. Films are thermally stable up to 325 C and contact angle of 25.1 showed a good wettability between substrate and hybrid matrix. Furthermore, films showed fast photochromic response after 1 min of ultraviolet exposure time. The bleaching process revealed that the relaxation process is dependent of the temperature and the activation energy of 47.2 kJ mol À1 was determined. The properties of these films make them potential candidates for applications in flexible photochromic materials.

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Section: Resultsmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Photochromic dynamics of organic–inorganic hybrids supported on transparent and flexible recycled PET

et al. 2017

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“…The composite PCM formed by the integration of the photochromic component and the phase change energy storage component improves the absorption of visible light through photochromism, resulting in stronger solar thermal conversion and better thermal energy storage. 12,16,27,29 Compared with organic photochromic materials, inorganic photochromic materials have received extensive attention due to their low cost and good stability, especially some transition-metal-oxidetype materials, such as heteropolyacids, WO 3 , MoO 3 , V 2 O 5 , and so on. 30,31 Among them, phosphotungstic acid (PA) is a photochromic material based on polyoxometalate.…”

Section: ■ Introductionmentioning

confidence: 99%

“…30,31 Among them, phosphotungstic acid (PA) is a photochromic material based on polyoxometalate. 32,33 It is incorporated into many hybrid matrices to achieve a synergistic effect between organic and inorganic parts to provide the required performance, such as PWA-diureasils organic− inorganic hybrids 29 and organic−inorganic hybrids supported on polyethylene terephthalate. 34 The Keggin structure of phosphotungstic acid makes it easy to accept peripheral electrons, thus showing a change in heteropoly blues.…”

Section: ■ Introductionmentioning

confidence: 99%

Design and Construction of Photochromic and Antileakage Reinforced Wood-Based Cellulose Microframework/Hexadecanol-Coconut Oil Composite Phase Change Material

2021

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The development of high-performance shape-stable phase change material composites (SPCMs) with high phase change enthalpy and high conversion efficiency, especially with good photochromic properties, is essential for thermal energy storage. Here, we report that one type of SPCMs with both photochromic and phase change energy storage is obtained by incorporating organic binary composite PCMs (hexadecanol/coconut oil, H/C) and photochromic phosphotungstic acid (PA) into Ochroma pyramidale wood-based cellulose microframe (DOW) through simple vacuum impregnation. When the ratio of hexadecanol to coconut oil is 3:7 and the ratio of phosphotungstic acid to N,N-dimethylacetamide is 4:13.6, the SPCM composite material (DOW-H3C7-4PA) represents a high phase transition enthalpy of 163.7 J/g and an appropriate phase transition temperature of 42.55 °C that can be applied to the environmental temperature adjustment of high-temperature areas (>40 °C) mentioned in this paper, in addition to the excellent thermal stability and photochromic stability; for example, even after 100 thermal cycles and UV radiation cycles, its phase transition enthalpy remains almost unchanged. The DOW-H3C7-4PA composite material also shows good shape stability and leakage resistance. In addition, the high photothermal conversion efficiency (65.71%) of DOW-H3C7-4PA is considered to be a promising candidate for photothermal energy storage applications. Therefore, the manufactured SPCMs (DOW-H3C7-4PA) have high latent heat, good melting/freezing cycle reliability, high photochromic stability, and remarkable light-to-heat energy conversion ability, making them show broad application prospects in energy conversion and storage devices.

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Synthesis and characterization of ordered mesoporous silica containing di-ureasil hybrid/phosphotungstic acid and Eu3+

Cavalcante

Molina

Martins

2019

J Mater Sci: Mater Electron

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PWA-diureasils organic–inorganic hybrids. Photochromism and effect of the organic chain length

Cited by 6 publications

References 18 publications

Photochromic dynamics of organic–inorganic hybrids supported on transparent and flexible recycled PET

Photochromic dynamics of organic–inorganic hybrids supported on transparent and flexible recycled PET

Design and Construction of Photochromic and Antileakage Reinforced Wood-Based Cellulose Microframework/Hexadecanol-Coconut Oil Composite Phase Change Material

Synthesis and characterization of ordered mesoporous silica containing di-ureasil hybrid/phosphotungstic acid and Eu3+

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