Synthesis, characterization and thermal properties of inorganic-organic hybrid

Da, Zulin; Zhang, Q. Q.; Wu, Dai-Lin; Yang, Duo; Qiu, Fengxian

doi:10.3144/expresspolymlett.2007.95

Cited by 24 publications

(18 citation statements)

References 18 publications

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“…The exothermic peak at T = 300 • C instead, is related to the oxidation of PVP chains and the bond of siloxane species. Table 3 shows the mass loss of all microfibre samples at T = 400 • C. From sample Mf-0 to Mf-8, the increasing weight loss at T = 400 • C is related to the concurrent thermal degradation of the organic and inorganic components of the hybrid structure [46]. In the remaining samples Mf-13, Mf-18, and Mf-24 the first endothermic peak in zone (II) is not visible because increasing the Si content the exothermic peak at T = 300 • C becomes larger and more dominant (Figure 4).…”

Section: Microfibres Thermal Characterizationmentioning

confidence: 99%

Manufacturing and Assessment of Electrospun PVP/TEOS Microfibres for Adsorptive Heat Transformers

et al. 2019

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A new adsorbent coating for the adsorber unit of an adsorption heat pump made of hybrid, organic-inorganic microfibres was prepared and characterized. Different coatings were obtained by the electrospinning of polyvinylpyrrolidone (PVP) solutions added with different quantities of tetraethyl orthosilicate (TEOS). PVP is a polymer with water adsorption capability and the TEOS addition allowed to increase the thermal stability of microfibres. The aim, indeed, was to preserve the polymeric structure of microfibres in order to obtain coatings with high flexibility and mechanical strength. The results demonstrated that TEOS concentrations in the range of 5-13 wt.% produced microfibre coatings of non-woven textile structure with both good water affinity and good thermal stability. SEM images of coatings showed that the deposited microfibre layers have both a high surface area and a high permeability representing a significant advantage in adsorption systems.Coatings 2019, 9, 443 2 of 12 and silica tetrahedra that form a crystalline nanoporous structure with hydrophilic behavior [14,15]. Although zeolites are the ideal adsorbing solid for the elevated thermal stability, their use in adsorption systems is limited by the high regeneration temperatures. The desorption of water vapor from the zeolite porosity requires temperatures above 300 • C for the complete material dehydration [16,17]. The ideal exploitation of this technology, indeed, is the coupling with low temperature heat sources (T < 150 • C), like solar thermal panels or waste combustion fumes [11,18]. For such a reason, other adsorbing materials have been proposed and sometimes used in solid sorption applications, like silica gel, alumino-phosphour zeotypes (AlPO and SAPO), and metalorganic frameworks (MOF). AlPO and SAPO are interesting for their high adsorption capacity, their good structural stability, and low regeneration temperatures but they are difficult to find on the market and costly [19,20]. MOF are new adsorbing materials with large water capacity and low regeneration temperatures, but their structural stability is still an open issue and they are expensive and difficult to find in large quantities [21,22]. Among others, silica gel is the adsorbent most used in commercial adsorption chillers mainly for its low cost and large availability on the market although it shows a lower water adsorption capacity and problems of morphological and thermal stability [22][23][24][25].Over the years, the scientific community has focused not only on the development of the porous material but also on the engineering of the absorber, the heat exchanger module where the adsorbent material is located. In order to reduce heat transfer resistances, the porous material distribution around the heat exchanger surfaces is very important. Zeolites and silica gel are generally used in form of granules or powder and the simplest and most used solution is to fill the free space between the fins of the heat exchanger with the adsorbent granules. In this case, however, the poor co...

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Section: Microfibres Thermal Characterizationmentioning

confidence: 99%

Manufacturing and Assessment of Electrospun PVP/TEOS Microfibres for Adsorptive Heat Transformers

et al. 2019

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“…They consist of chains exclusively made up of silicon atoms with significant delocalization of the sigma electrons along the backbone. This aspect leads to interesting electrical and optical properties, such as high quantum efficiency of charge generation, high charge-carrier mobility, efficient luminescence, and optical non-linearity [18]. Their photophysical properties are strongly influenced by the chemical structure of the polymer side groups and/or dimensionality of the skeletal framework [19,20].…”

Section: Introductionmentioning

confidence: 99%

The influence of polysilane chemical structure on optical properties, rubbed film morphology and LC alignment

Soroceanu¹,

Barzic²,

Stoica³

et al. 2015

Express Polym. Lett.

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Abstract. Polysilane films were prepared by the drop casting method and their optical and morphological properties have been analyzed in order to investigate their suitability as alignment layers for nematic molecules. The samples do not absorb the radiations in the visible domain, particularly those containing methylhydrosilyl units, and present a transmittance of about 90% starting from 390 to 1100 nm. The optical band-gap is higher than 3.26 eV for all polysilanes indicating a low probability of optical absorption processes in the visible range. The morphology of the pristine samples shows isotropically distributed granular formations. The polymer surface was oriented by rubbing with two types of velvet: one with short fibers and the other with long fibers. The latter generates higher surface anisotropy, as shown by the reduction of the surface texture direction index values. The presence of methylhydrosilyl units allows a denser packing of the polymer structure and thus finer surface periodicities, leading to better orientation of the nematic molecules on the polysilane surface.Keywords : material testing, polysilane, rubbing, morphology, LC alignment eXPRESS Polymer Letters Vol.9, No.5 (2015) 456-468 Available online at www.expresspolymlett.com DOI: 10.3144/expresspolymlett.2015.43 * Corresponding author, e-mail: irina_cosutchi@yahoo.com © BME-PT layer in the visible domain. The surface morphology of the rubbed alignment layer, the pretilt angle and surface energy of the alignment film are influenced by the conformation of the polymer molecular backbone [9]. Many studies are focused on preparing alignment layers by rubbing polyimides [10][11][12][13], poly(vinylidene fluoride) [14] or polyamides [15]. Since the absorption characteristics of alignment layer determines unwanted light-transmission modulation of the liquid crystal leading to ghost images on the LCD panel [16,17], the investigations are focused on transparent polymers with good surface alignment ability. Another class of transparent polymers is represented by polysilanes. They consist of chains exclusively made up of silicon atoms with significant delocalization of the sigma electrons along the backbone. This aspect leads to interesting electrical and optical properties, such as high quantum efficiency of charge generation, high charge-carrier mobility, efficient luminescence, and optical non-linearity [18]. Their photophysical properties are strongly influenced by the chemical structure of the polymer side groups and/or dimensionality of the skeletal framework [19,20]. To our knowledge there are no investigations on polysilane-based alignment layers patterned by rubbing. Previous papers [21][22][23] showed that polysilanes exhibit good ability of aligning molecules. The morphological features of these polymers are affected by UV exposure due to the scission of the main chain and oxidation processes [21]. Since UV-irradiated polysilane generated different orientation of nematic molecules from that induced non-irradiated polymer, pattern...

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“…This considerable scientific and engineering interest has been stimulated by possibility of the significant improvements in physical, mechanical, thermal and other important specific properties of PLS materials. The results of these researches were summarized and discussed in several reviews and articles [1][2][3][4][5][6][7]. PLSs are a class of organic-inorganic hybrids, composed of organic polymer matrix in which layered silicate particles of nano-scale dimension are embedded because these nanocomposites show enhanced mechanical properties [8,9], gas barrier properties [10], and improved thermal stability [5,11,12], low flammability [11,12] and protection effects from corrosion [13,14].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of functional copolymer/organo-silicate nanoarchitectures through interlamellar complex-radical (co)terpolymerization

Söylemez¹,

Caylak²,

Rzayev³

2008

Express Polym. Lett.

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Abstract. The functional copolymers, having a combination of rigid/flexible linkages and an ability of complex-formation with interlayered surface of organo-silicate, and their nanocomposites have been synthesized by interlamellar complex-radical (co)terpolymerization of intercalated monomer complexes of maleic anhydride (MA) and itaconic acid (IA) with dimethyl dodecylamine surface modified montmorillonite (organo-MMT) (MA…DMDA-MMT and IA…DMDA-MMT) n-butyl methacrylate (BMA) and/or BMA/styrene monomer mixtures. The results of nanocomposite structure-composition-property relationship studies indicate that interlamellar complex-formation between anhydride/acid units and surface alkyl amine and rigid/flexible linkage balance in polymer chains are important factors providing the effective intercalation/exfoliation of the polymer chains into the silicate galleries, the formation of nanostructural hybrids with higher thermal stability, dynamic mechanical behaviour and well dispersed morphology.

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Synthesis, characterization and thermal properties of inorganic-organic hybrid

Cited by 24 publications

References 18 publications

Manufacturing and Assessment of Electrospun PVP/TEOS Microfibres for Adsorptive Heat Transformers

Manufacturing and Assessment of Electrospun PVP/TEOS Microfibres for Adsorptive Heat Transformers

The influence of polysilane chemical structure on optical properties, rubbed film morphology and LC alignment

Synthesis and characterization of functional copolymer/organo-silicate nanoarchitectures through interlamellar complex-radical (co)terpolymerization

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