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1. WO2020109855 - FABRICATION DE COMPOSITES DE CARBURANTS THERMIQUES SOLAIRES POLYMÈRES APPLICABLES EN TANT QUE STFF, STFI, STEG, STFP

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

Fabrication of polymeric solar thermal fuel composites applicable as STFF, STFI,

STEG, STFP

Description

Technical Field:

The technical field of the present invention is the chemistry of materials mostly applied in the production of clean energy (renewable energy).

Technical Problem:

In recent years, global warming and climate change arising from C02 emissions have led to significant concerns. Solar energy is among the most abundant renewable energy sources in the world. Despite the abundance of sunlight radiation, effective saving and conversion of this source have caused some challenges. The best type of solar cell only can convert about 15% of absorbed solar energy into electricity. Therefore, the use of other methods to increase the efficiency of solar energy storage and conversion has received a great deal of interest in the world. One of the energy storage methods that can convert 100% of stored solar energy to other forms of energy is the use of solar thermal fuels materials. Solar Thermal Fuels are materials that change their structure or conformation upon sunlight absorption, store absorbed solar energy in their molecules and triggered by a driving force such as temperature or light release stored energy immediately as thermal energy or over time in the absence of any driving force release solar energy as thermal energy. Solar Thermal Fuels is abbreviated as STF

So far, the various STF molecules that have been studied have encountered numerous problems, including thermal instability, degradability, and the high cost of STF molecule elements, which are main drawbacks to utilize them extensively. But in the last decade, azobenzene molecules that have properties, such as high thermal stability, low degradability, and proper sunlight absorption, have been considered as appropriate STF molecules. These molecules have the ability to change in two trans and cis

conformation, and since the optical properties of materials can be examined by the electrons inside materials, theories on the optical properties of these molecules are defined, which ultimately led to Density Functional Theory (DFT).

By using computer software, the amount of energy in two different conformations of azobenzene molecules can be determined based on quantum physics, and then, by using the relevant software, the amount and duration of energy release in these materials can be obtained. Scientists have been trying to increase the amount of stored energy in these materials, which have ultimately increased the stored energy in these materials by bonding carbon nanotubes filler or graphene oxide with azobenzene molecules and creating a steric hindrance in azobenzene molecules. The technical problems of this research are the impossibility of commercialization of these products due to the harmful and toxic solvents, the longtime production and incorporation of expensive materials, which ultimately obviate the possibility of industrial fabrication of such products. The primary purpose and focus of the present invention was to devise a new and suitable method for functionalization of filler or nanofillers with azobenzene molecules and dispersion of azobenzene modified with various fillers in a variety of polymeric substrates and the fabrication of a new applied product. In this invention, a method for the preparation of a polymeric solar thermal fuel product based on a new synthesis method for modifying the azobenzene molecules with filler or nanofillers and loading a modified azobenzene molecule with various fillers in a variety of polymeric substrates to produce polymeric solar thermal fuel composites is proposed. This composite can be used to produce films, sheets, pains, fibers and films made for the production of solar thermoelectric generators.

Prior Arts:

Invention with application number CN107201214A in 2017, Tianjin University has introduced a new synthesis method for the functionalization of graphene oxide by azobenzene. In this method, the time of releasing energy and heat storage density in the heterocyclic azobenzene molecule is increased, and the heterocyclic

azobenzene/grapheme hybrid is proposed as an alternative to lithium batteries. In this invention, the heat storage density is improved by nearly 50 percent compared with that of the heterocyclic azobenzene molecules.

Another invention with application number WO2012177320A1 , in 2012, MIT University, has functionalized single-wall carbon nanotube with azobenzene molecules. In this invention, by creating a structure between nanoparticles and azobenzene groups, the steric hindrance was created between the molecules and also by functionalization of the nanoparticle with azobenzene molecules, the hydrogen bonds were created between nearby azobenzene molecules. These two actions resulted in increasing the amount of stored energy and the time of releasing energy. These functionalized nanoparticles with azobenzene groups due to steric hindrance; exhibit a half-life of greater than one year which is widely used in the lithium battery industry.

In the present invention, modification of azobenzene molecules with filler or nano-filler by esterification and loading of modified azobenzene molecules with a polymer solution or melt mixing in polymeric substrates for the production of solar thermal composites was performed. The functionalization of filler or nanofiller with azobenzene molecules increases the energy stored in the azobenzene molecules. The dispersion of functionalized fillers with the azobenzene molecules induces the transfer of energy produced in polymeric substrates. Functionalization of filler or nanofiller with

azobenzene molecules will lead to covalent bonds and steric hindrance which finally, increases the stored energy by (filler-azobenzene molecules) structure in the polymeric substrate. The advantage of the present invention in relation to other inventions including the increased density of azobenzene molecules, optimal use of azobenzene

molecules, non-use of toxic solvents such as thionyl chloride, production of polymeric solar thermal fuel composites for use in the generation of thermal energy and electrical energy, increased energy storage density and cost-effectiveness. This polymeric solar thermal fuel product can be used for general use, including heating homes, clothes, anti-icing, hybrid solar cells and the solar thermoelectric generator used throughout the day.

Description of Invention:

The primary purpose for the present invention is to illustrate ways of dispersion and increasing the efficiency of azobenzene modified with filler or nanofiller in diverse substrates to produce a new product. This invention tries to indicate the loading of azobenzene molecule modified with diverse fillers or nanofillers in a variety of polymeric substrates. Azobenzene modification improves energy storage density in these materials, and the loading of modified azobenzene with various fillers or nanofillers results in the production of the polymeric composite having the potential to store solar energy in the present of sun light and convert this energy to the thermal energy. Since polymers are a thermal insulator, in the percentages of fillers or nano-fillers, a rise in conductivity will occur. Free electrons through an electronic transition transfer energy into the composite, which results in thermal conductivity. In these products, the effective transfer of heat makes it possible to produce a consumer product; by loading a small percentage percentage of azobenzene modified with a variety of fillers or nanofillers, a product with high thermal transfer efficiency (utilizing azobenzene molecules in various industries require substrates such as polymers for dispersion).

This invention seeks to produce a useful product using modified azobenzene molecules. The fillers or nanofillers functionalized by the azobenzene molecule in the optimal percentage form the thermal conductors within the polymeric substrate and release the energy stored in the polymer substrate after 3 to 10 hours (depending on the structure of the azobenzene molecule, fillers, and polymers). The polymer composite stores solar energy and releases it as heat over time.

In this invention, one or a combination of carbon nanotubes, graphene, calcium carbonate, barium sulfate or sodium sulfate or clays as a filler or nanofiller, was used. Also, the polymeric substrate used is one or a combination of polymers with a glass transition temperature less than 10 ° C, including ethylene vinyl acetate, copolymer or polymer of propylene, copolymer or polymer of polyethylene, polystyrene butadiene styrene (SBS) poly (styrene-ethylene-butylene-styrene)(SEBS), polyethylene glycol, polybutadiene, polyethylene terephthalate , Polyisoprene , TPU Polymer(thermoplastic polyurethane), Polyvinylpyrrolidone (PVP), Polyurethane, Polyvinyl chloride(PVC), Polyvinylidene fluoride (PVDF), Polychloroprene, Polycaprolactone, . Azobenzene molecules that have a hydroxyl functional group in their structure are also useful in this synthesis method and fall within the scope of this invention.

For confirmation of this claim, Azobenzene molecule on multi-walled carbon nanotubes was functionalized by esterification and loading of modified azobenzene molecules with a polymer solution or melt mixing in a polymeric substrate for the production of solar thermal nanocomposites is presented. The multi-walled carbon nanotubes

functionalization with azobenzene molecule (4- (4-nitrophenylazoyl) -phenol )was performed with esterification as an example to confirm this claim. Multi-walled carbon nanotubes functionalized with azobenzene molecule( 4- (4-nitrophenylazoyl) -phenol )by polymer solution or melt mixing in ethylene vinyl acetate (28%) were dispersed.

Modifying azobenzene molecules using multi-walled carbon nanotubes and creating a multi-walled carbon nanotubes-azobenzene structure causes a steric hindrance and, consequently, increases the energy storage density in azobenzene molecules. The loading of azobenzene modified with multi-walled carbon nanotubes in 28%

polyethylene vinyl acetate and the dispersion of multi-walled azobenzene carbon nanotubes in a polymeric blend of 28% polyethylene vinyl acetate leads to the production of polymeric solar thermal composite which is used as a solar thermal fuel or solar thermoelectric generator. This blend is not only used as solar thermal fuels, but also it has the ability to save solar energy to convert this energy into other forms of energy (electrical power) for different applications. By functionalizing multi-walled carbon nanotubes with azobenzene molecules and producing polymeric solar thermal fuel composite, one can combine azobenzene groups and increase the density of azobenzene molecules.

Multi-walled carbon nanotubes (MWNTs) used in this invention is those functionalized with carboxylic groups. The weight percent of carboxyl groups on multi-walled carbon nanotubes ranges 3% - 8%, preferably between 3% and 5%. The purity of the multi-walled carbon nanotubes is more than 90% and preferably more than 95%. The length of the multi-walled carbon nanotubes is between 5 to 30 pm and preferably between 10 and 20 pm. The average inside and outside diameter of the carbon nanotubes is between 5 nm to 15 nm, preferably 7 nm to 13 nm. In this invention, the azobenzene molecules used have a hydroxyl functional group in their structure. Azobenzene molecule 4- (4-nitrophenylazoyl) -phenol is used as azobenzene molecule with the hydroxyl group, although the synthesis of other azobenzene molecules having a hydroxyl functional group in their structure is possible, so it falls within the scope of this invention.

A sample of azobenzene molecules, called 4- (4-nitrophenylazoyl) -phenol, is formulated as follows:

Methyl nitrite is applied as solutions in one or a combination of water, ethanol, ether, water - methanol solvents in wt% 5 - 95%. in case of using water - methanol blend as a solvent, water to methanol ratio is between 0.2: 5. The hydrochloric acid used in this product is selected with a purity of 90% to 99%, preferably from 95% to above.

Hydrochloric acid and sodium nitrite are mixed in a water and ice bath between 2 to 5

hours and methyl nitrite solution. To prepare nitro aniline salt with 90-99% purity, preferably 95%, first, hydrochloric acid is mixed with 4-nitroaniline and methanol with a mechanical stirrer and then mixed with methylene nitrite solution at 0 ° C for 3 to 5 hours. By Using a mechanical stirrer, the phenol and nitroaniline salt are mixed with PH from 8 to 10, preferably PH = 9, and the desired product, which is 4- (4-nitrophenylazoyl) -phenol, is obtained using hydrochloric acid as a substance. It should be noted that the product yield productivity ranges 90% - 95%.

The meaning of the abbreviations in the name of the invention is as follows:

STFF: Solar Thermal Fuel Film

STFI: Solar Thermal Fuel Fiber

STEG: Solar Thermoelectric Generator

STFP: Solar Thermal Fuel Paint

Brief Description of Drawings:

Figure 1 : Synthesis mechanism of azobenzene molecule 4- (4-nitrophenylazoyl) -phenol Figure 2: Isomerisation mechanism

Figure 3: Solar Thermal Fuel Film (STFF)

Figure 4: Solar Thermal Fuel Fibers (STFFI)

Figure 5: Solar Thermal Fuel Paint (STFP)

Figure 6: Solar Thermoelectric Generator

Figure 7: Hybrid Solar Cell

Figure 8: Solar Thermal Fuel Coating

Detail Description of Drawings:

Fig 1

Synthesis mechanism of azobenzene molecule (1 ) and isomerization mechanism in azobenzene molecule (2).

The azobenzene molecule serves as a molecule that can be used to functionalized multi-walled carbon nanotubes. This invention is proposed for the modification of the azobenzene molecule and the functionalization of multi-walled carbon nanotubes with azobenzene molecules by esterification method. Fig. 2 illustrates the ways of

establishing a covalent bond between the azobenzene molecule and multi-walled carbon nanotubes through the esterification process.

Fig 2

The functionalization method of 4- (4-nitrophenylazoyl) -phenol as azobenzene molecules has a hydroxyl group on multi-walled carbon nanotubes as follows:

Initially, nanoparticles are dispersed in dimethylformamide (DMF) to open nanoparticle multi-walled carbon nanotubes using an ultrasonic device at a frequency of 30 to 80 khlz. 4- (4-nitrophenylazoyl) -phenol is dissolved in a DMF solvent with a purity of 90%, preferably 95%. Then the solution of DMF with azobenzene, is added to the multi-wall carbon nanotubes mixture. Sulfuric acid is added to the mixture with a purity of 98% as a catalyst. Since the reaction of esterification is reversible and it produced water as a byproduct in the reaction, by controlling the amount of water produced, the reverse reaction can be prevented. Therefore, the conditions for doing this reaction are considered.

The temperature of the mixture is considered to prevent the production of water in the reaction 35 to 65 degrees. The mixture is pressurized by gases such as argon, nitrogen, preferably nitrogen. In order to prevent the production of water in the reaction, a certain amount of toluene is added to the mixture over a specified time period to create an Azeotrope point between the water and the toluene and reduce the boiling point of water and make the water vapor to remove water from the mixture. For preventing the reverse reaction, the amount of azobenzene molecule is used as surplus. This reaction takes place within 1 to 2 hours. Finally, multi-walled carbon nanotubes functionalized with azobenzene molecule are separated by using a vacuum filtration set with a pore diameter of between 0.02 and 0.45 pm.

To remove the exceeded azobenzene molecules, additional solvents that have azobenzene molecule solubility, such as methanol, acetone, ethanol, tetrahydrofuran, and preferably acetone, are used. Using a centrifuge, an additional amount of azobenzene molecule is separated at 8500 rpm for 10 minutes. As a result, Flydroxyl and carboxyl groups form a carbonyl group by covalent bonding. The azobenzene molecule is placed on multi-walled carbon nanotubes. These covalent connections create a structure and steric hindrance, resulting in a high-performance energy storage product.

The multi-wall carbon nanotubes functionalized with azobenzene molecules is performed by ultraviolet light in a spectrum between 200 and 450 nanometers. In this ranges solar energy stored and release in the form of thermal energy over a specified period without forcing driver. The effective wavelengths which affect isomerization depend on how the functional groups are placed on the azobenzene molecules. Also,

functional groups on azobenzene molecules play an essential role in the duration of releasing energy.

The time of releasing energy is between 3 and 10 hours. Although azobenzene molecules with hydroxyl groups due to hydrogen bonding have a longer release time, are used as an alternative to the lithium battery industry. In the following, the loading and dispersion of azobenzene molecule modified by carbon nanotubes to produce a polymeric solar thermal nanocomposite are presented. It should be noted that for the production of a polymeric solar thermal composite (polymeric solar thermal fuel product), all organic photoswitchable molecules such as Azobenzene molecules, spiropyran, Diarylethene, spirooxazine, Fulgid and all molecules based on modified organic photochemical molecules with nanofiller or filler compatible with given polymer type (polar or nonpolar) can be used and hence are within the scope of this invention. This section has practical importance. Applicable azobenzene compound in various industries is impossible without using substrates such as polymers and ignoring strategies for dispersion of photoswitchable molecules such as azobenzene in polymers. For this reason, in this section, we deal with the loading of azobenzene molecules modified with nanofillers in a polymeric substrate for effective heat transfer and the production of a consumer product: The loading of modified azobenzene molecules is carried out in two ways: polymer solution or melt mixing. First, loading modified azobenzene molecules by polymer solution method is as follow:

The polymer for this purpose is ethylene vinyl acetate is preferably ethylene vinyl acetate (28%). After dry-washing in an ultrasonic apparatus with a frequency of 30 to 80 kFIz Multi-walled nanotubes functionalized with azobenzene molecule is dispersed in tetrahydrofuran (TFIF) solution at concentrations ranging from 0.001 to 0.5, preferably 0.005 to 0.1 (g / ml).

Ethylene vinyl acetate 28% dissolved in tetrahydrofuran (TFIF) at a concentration between 0.001 and 0.5 and preferably from 0.05 to 0.1 (g / ml) for 2 to 4 hours. Multi-wall carbon nanotubes-azobenzenes that are dispersed in tetrahydrofuran (TFIF) solvent are added to the polymer solution. Multi-wall carbon nanotubes- azobenzene are dispersed in ultrasonic apparatus in ethylene vinyl acetate solution for 1 to 2 hours. The solvent tetrahydrofuran (THF) in the Azobenzene modified with carbon nanotubes, dispersed in the polyethylene vinyl acetate, evaporates, and the nanocomposite film is produced using a press machine as a uniform film.

The melt mixing way is as follow: It is expressed by using an internal mixing machine at a temperature of 65 ° to 75 ° with a 60 rpm for mixing and loading Azobenzene modified with carbon nanotubes in the polymer substrates. Mixing of ethylene vinyl acetate polymer with an azobenzene- multi-walled carbon nanotube.lt takes 5 minutes and then the melt (ethylene-vinyl acetate polymer (azobenzene -multi-walled nanotube)) is produced using a press machine in the form of a film.

The film produced using two methods of solution and melt loading in a thickness of 5 pmto 5 mm, is capable of storing solar energy and releasing it as heat. It is used as a film, fiber, paint and thermoelectric generator films, which, by absorbing sunlight, store the absorbed energy in its molecules, instantaneously with the triggers such as temperature or light, release stored energy as thermal energy or after a certain period of time without a triggers, released stored energy as heat.

In addition, conversion of solar energy with modified azobenzene molecule and heat transfer in polymer composites reduce the production costs of polymeric solar thermal products, create favorable azobenzene molecules and also increase the density of azobenzene molecules within a polymer composite.

The main innovation and novelty of this invention is the loading of azobenzene molecules modified with diverse fillers or nanofiller in polymeric substrates by solution or melt mixing method— azobenzene modified with a carbon nanotubes loaded in a polymer ethylene vinyl acetate 28% is performed with ultraviolet light in a spectrum between 200 and 450 nm and store solar energy and releases this energy by a triggers such as temperature or light or without a triggers after a certain period of time (3 to 10 hours) as thermal energy.

This approach is a significant step towards the industrialization of new materials in the field of renewable energy. Modified azobenzene is an alternative to fossil fuels and as a source of thermal energy throughout the 24 hours of day in the automotive industry, the paint industry, the textile industry, hybrid solar cell, home heating, building industry and thermoelectric generators.

Figure 3, Solar Thermal Fuel Film (STFF): indicates the mechanism of using final consumer product (solar thermal fuel films or sheets) in the energy industry field.

Figure 4, Solar Thermal Fuel Fibers (STFFI): indicates the application of final consumer product (solar thermal fuel fibers) as coating layers on clothes which can store solar energy in the presence of sunlight (day) and release this energy as heat at night.

Figure 5, Solar Thermal Fuel Paint (STFP): indicates the application of final consumer product ( solar thermal fuel paint) as sprayed or coating layers in the building surface or on the surface of curtain, furniture or carpet in the house in order to absorb sunlight and store solar energy at day time and release this energy as heat at night.

Figure 6, Solar Thermoelectric Generator: indicates the application of final consumer product (solar thermoelectric generator) as films or sheet to make multilayer n-type (4) and P-type (5) films in the thermoelectric generator device (3) and use this device as a solar thermoelectric generator. In this device, at the day time, solar thermal fuel films (4,5) store solar energy, and at night, these materials release energy as heat. This temperature difference between solar thermal fuel films and insulator layer (6) generates electricity at night.

Figure 7, Hybrid Solar Cell: indicates the application of final consumer product (hybrid solar thermal cell) as coating layer of solar thermal fuel in solar cell generate electricity in 2 ways:

First: The layer of solar thermal fuel films work as anti acing, and it avoids solar cell from freezing in winter because these layers store solar energy at the day time and release this energy at night.

Second: Since the solar cell just can be used in the presence of solar radiation, these layers can be used as the thermoelectric generator on the surface of the solar cell panel to generate electricity at night.

Figure 8, Solar Thermal Fuel Coating: indicates the application of final consumer product (solar thermal fuel coating) as layers of solar thermal fuel films can be used as anti acing in the surface of house and cars to prevent them from freezing in the winter by the mechanism of storing solar energy at the day time and release this energy as heat at night.

Advantages of the Invention:

1 . Cost-effectiveness (low product costs)

2. Optimal utilization of Azobenzene compound

3. Increased density of azobenzene molecules in polymer composites

4. Dispersion of azobenzene modified with various fillers in a diverse of polymeric substrates

5. Production of polymeric solar fuel composites

6. Using environmentally friendly solvents

7. Creating great opportunity to use innovative products in the energy industry field

8. The short reaction time of production

9. Production of various types of solar thermal fuels products with different shapes and dimensions with appropriate thermal properties

A Practical Approach to Invent Implementation:

The implementation method of the invention is that first in a static pilot reactor the photoswitchable molecules (azobenzene) are modified by the esterification process. For purifying the modified azobenzene molecules, the filtration set is used, and the industrial dryers are used to dry and remove the solvent in the particles. In the next step, according to the type of requirements in various industries, solution and melt mixing methods are used to produce the polymeric solar thermal composites. It should be noted that photoswitchable molecules are used as an applicable solar thermal fuel polymer composite with an ability to store and release energy as reversible cycle overnight.

1 . Textile industry: Using fiber spinning devices, photoswitchable molecules can be used as polymeric solar thermal fibers to make self-warming garments.

2. Paint industry: Using polymer resins, photoswitchable compounds can be used as sprays and coatings paints in residential and office buildings. It also can be used in the form of coatings on the surface of furniture, curtains, carpets, clothes as thermal power.

3. Automotive Industry: photoswitchable compounds can be used as coating layers as an anti-icing coating for use throughout the day.

4. Solar cell industry: photoswitchable compounds can be used in 2 ways for solar cell

1 - Photoswitchable compounds are used as protective layers on a solar cell to melt the ice created during the cold seasons.

2- Photoswitchable compound in the form of a layer as a source of electrical energy for the use of solar cells in the absence of direct sunlight with the mechanism available in the thermoelectric generator.

Explicit Industrial Application of Invention:

It is possible to utilize this product as an alternative to renewable energy in various industries, including:

1 . Paint production industry

2. Textile industry

3. Automotive industry (Anti-ice)

4. Hybrid Solar Cells

5. Home heating systems

6. Building industry

7. Thermoelectric generator