ELECTROCHROMIC WIRE THREAD AND RELATIVE FABRICS

Abstract

The present invention is directed to eyectrochromic, supercapacitor yarns and the related fabrics. An electrochromic yarn formed by two interwind threads has been invented. The yarn is electrically isolated by a transparent, uncolored polymer. Each thread is the superposition of three concentric layers. The most internal one, the core, has the function of support and/or conductive layer, the second one is the eiectrochromic layer containing conductive nanoparticies, the third layer is a polymer dielectric blend. The yarns described above allows to generate electrochromic fabrics in which the colour can be varied by the application of small electric voltages fed by a battery with variable power supply controlled by a microprocessor connected to a smartphone via Bluetooth technology. A specific application on the smartphone allows to change the voltage supply to the fabrics, in order to get the desired chromatic change.

Claims

1. An electrochromic yarn formed by two interwinded threads electrically isolated by a protective layer of non-electrically conductive polymer, characterized by the fact that each thread is the superposition of three concentric layers, the first is the supporting and conductive core, the second is an electrochromic active layer, comprising a polymeric compound containing conductive nanoparticles, the third is a polymeric dielectric blend and that its break resistance is comprised between 35 and 185 Mpa.

2. An electrochromic yarn according to claim 1 characterized by the fact that the supporting and conductive core is a metallic electric conductor.

3. An electrochromic yarn according to claim 1 characterized by the fact that the supporting and conductive core is an Intrinsic Conductive Polymer.

4. An electrochromic yarn according to claim 1 characterized by the fact that the supporting and conductive core is of cellulosic type and is coated with single walled carbon nanotubes (SWCNT).

5. An electrochromic yarn according to claim 1 characterized by the fact that the supporting and conductive core is of cellulosic type and is coated with PEDOT:PSS/SWCNT and the active electrochromic layer is formed by PEDOT:PSS/SWCNT.

6. An electrochromic yarn according to claim 1 characterized by the fact that the supporting and conductive core is of cellulosic type and is coated with PEDOT:PSS/SWCNT which also has electrochromic properties and the electrochromic active layer consists of PMMA/PEO/SWCNT/NMP/EV/Fc, that is, a blend of thermoplastic polymer incorporating SWCNTs, plasticizers and small electrochromic molecules.

7. An electrochromic yarn according to claim 1 characterized by the fact that the supporting and conductive core is of polyester type and is coated with PEDOT:PSS/SWCNT and the electrochromic active layer is formed by PEDOT:PSS/SWCNT.

8. An electrochromic yarn according to claim 2 characterized by the fact that in which the electrochromic active layer is formed by PMMA/PEO/SWCNT/NMP/EV/Fc, that is, a thermoplastic polymer blend incorporating SWCNTs plasticizers and small active electrochromic molecules.

9. An electrochromic yarn according to claim 2 characterized by the fact that the electrochromic active layer is formed by PMMA/PEO/MWCNT/NMP/EV/Fc, that is, a thermoplastic polymer blend incorporating MWCNTs plasticizers and small active electrochromic molecules.

10. An electrochromic yarn according to claim 3 characterized by the fact that the electrochromic active layer is formed by PMMA/PEO/SWCNT/NMP/EV/Fc, that is, a thermoplastic polymer blend incorporating SWCNTs plasticizers and small active electrochromic molecules.

11. An electrochromic yarn according to claim 3 characterized by the fact that the electrochromic active layer is formed by PMMA/PEO/MWCNT/NMP/EV/Fc, a thermoplastic polymer blend incorporating MWCNTs plasticizers and small active electrochromic molecules.

12. An electrochromic yarn according to claim 2 characterized by the fact that the electrochromic active layer is formed by PVB/SWCNT/NMP/EV/Fc, that is, a thermoplastic polymer blend incorporating SWCNTs, plasticizers and small active electrochromic molecules.

13. An electrochromic yarn according to claim 2 characterized by the fact that in which the electrochromic active layer is formed by PVB/MWCNT/NMP/EV/Fc, that is, a thermoplastic polymer blend incorporating MWCNTs, plasticizers and small active electrochromic molecules.

14. Fabrics in which weft and warp threads are formed by the electrochromic according to claim 3.

15. Fabrics according to claim 14 characterized by the fact that it comprises a variable voltage supply battery in the range 2.4-3.6 V, with a microprocessor voltage regulator, equipped with Bluetooth connectivity for Smartphone connection.

16. Fabrics according to claim 15 characterized by the fact that it comprises a smartphone application with graphic interface for tuning the chromatic variation of the electrochromic fabrics.

Description

A BRIEF DESCRIPTION OF THE FIGURES

[0005] FIG. 1 represents a complete electrochromic wire thread, according to the present invention, composed of two intertwined fibres, covered by an electrically insulating polymer layer, in which with the number 11 the electrochromic wire 1 is illustrated, with the number 12 the electrochromic wire 2 is indicated, and the insulating polymeric coating is indicated with the number 13.

[0006] FIG. 2 represents an axonometric view and a section of an electrochromic wire thread with the different layers that compose it, in which the support/conductive core is represented with 21, the electrochromically active layer with 22, and the electrolytic Polymeric blend layer with 23.

[0007] FIG. 3 represents an electrochromic fabric and the switching voltage control system of the electrochromic fabric, in which the electrochromic fabric is represented with 31, the voltage regulator with 32, the microprocessor with 33, the Bluetooth module with 34 and the user interface for the choice of colour for the fabric with 35.

EXAMPLES OF EMBODIMENTS OF THE PRESENT PATENT

Example 1

[0008] An electrochromic wire thread in which each of the intertwined fibres is formed of a conductive core and a support in PANI/SWCNT, an active electrochromic layer of PMMA/PEO/SWCNT/NMP/EV/Fc, a layer of dielectric polymer blend of PMMA/PEO. Each fibre that constitutes the intertwined thread is created according to the following procedure: [0009] 1) A conductive core and a support, made of a Polyaniline fibre (PANI) created following the procedure illustrated by Pomfet et al. Polymer 41 (2000) 2265-2269, by wet spinning. A solution of PANI protonated with 2-acryloamide-2-methyl-1-propane sulfonic acid (molar ratio 1:0.6) in dichloroacetic acid (10% solution) was used, using acetone as a coagulating solvent. The fibres, with a diameter of 150 micrometres, were stretched room temperature and were found to have a conductivity of 1920 Siemens cm-1 and a Young's modulus equal to 48 MPa. [0010] 2) An active electrochromic layer, made in the following manner: a solution containing 40% of Methyl Methacrylate (MM), 5% of Poly Ethylene Oxide (PEO), 50% of N-Methyl Pyrrolidone in which some Single Wall Carbon Nanotube (SWCNT) have been suspended, in proportion equal to 0.5 mg/ml, 2% of Ferrocene (Fc), 2.9% of Ethyl Viologen (EV) and 0.1° A of a radical initiator for UV polymerization. The fibre referred to in Step 1 was immersed in this solution, keeping the two extremities out, thus coating it with a thin layer of it. The fibre was then subjected to UV irradiation for 5 minutes. The layer of solution was thus congealed in a Polymethylmethacrylate (PMMA) polymer coating. The procedure was then repeated until the PMMA coating had formed a layer of 50 micrometres. [0011] 3) A dielectric polymeric blend layer, made using a solution containing 50% of methyl methacrylate, 25% of PEO, 25% of Propylene Carbonate (PC). To this solution lithium perchlorate (LiCIO4) in a concentration of 1 molar and 0.5% of the total mass of a radical initiator was added. The thread coming from stage 2 was dipped several times in the solution, keeping out the extremities, and was irradiated with UV each time until a layer of 50 micrometres of dielectric polymeric film had formed on it. [0012] 4) The formation of the intertwined electrochromic thread. Two portions of fibre prepared as illustrated in the previous steps were woven together. [0013] 5) The electrical insulation of the wire. The thread resulting from Step 4 was inserted into a reactor, keeping the extremities out, in which Polyethylene glycol 1400 and the aliphatic diisocyanate 2,2,4-trimethyl-hexamethylene diisocyanate had been nebulized in Microdrops of 25 micrometres in diameter. The above components, reacting to form the urethane bond, generated the coating of the wire with a layer of transparent, insulating, mechanically resistant polyurethane. A wire with an average diameter of 0.6 mm was obtained. The wire thread thus produced is an electrochromic system that passes from transparency to an intense blue colour when powered with a voltage of 2 volts.

Example 2

[0014] An elettrochromic wire thread formed of fibres with a supporting conductive core in PANI/MWCNT, an electrochromically active layer of PMMA/PEO/SWCNT/NMP/EV/Fc, and a dielectric polymer blend of PMMA/PEO fibre. The example is analogous to Example 1, different only for the fact that MWCNTs were used in place of the SWCNTs.

Example 3

[0015] A wire thread formed of fibres with a conductive support core of PEDOT: PSS, an electrochromically active layer of PMMA/PEO/SWCNT/NMP/EV/Fc, and a dielectric polymer blend layer of PMMA/PEO.

[0016] The thread is created as described in Example 1. The procedure for preparing the fibres to be intertwined is precisely analogous to that of Example 1 but, the supporting conductive core is made of PEDOT: PSS polymer instead of PANI. The electrochromic wire behaves analogously to that of Example 1.

Example 4

[0017] A wire thread formed of fibres with a conductive support core of PEDOT: PSS, an electrochromically active layer of PMMA/PEO/MWCNT/NMP/EV/Fc, and a dielectric polymer blend of PMMA/PEO.

[0018] The example is analogous to Example 3, being different only for the fact that MWCNTs were used in place of the SWCNTs.

Example 5

[0019] A wire thread formed of fibres with a conductive support core of metal, an electrochromically active layer of PMMA/PEO/SWCNT/NMP/EV/Fc, and a dielectric polymer blend layer of PMMA/PEO.

[0020] The thread is created as described in Example 1. The procedure for the preparation of the electrochromic fibre is analogous to that of Example 1, apart from the fact that Step 1 is eliminated in as much as the conductive support core was substituted by a copper wire with a diameter of 50 micrometres. The electrochromic fibre behaves in a manner analogous to that of Example 1.

Example 6

[0021] A wire thread formed of fibres with a conductive support core of metal, an electrochromically active layer of PMMA/PEO/SWCNT/NMP/EV/Fc, and a dielectric polymer blend layer of PMMA/PEO.

[0022] The example is analogous to Example 5, being different for the fact that MWCNTs were used in the place of the SWCNTs.

Example 7

[0023] A wire thread formed of fibres with a conductive support core of metal, an electrochromically active layer of PVB/PEO/SWCNT/NMP/EV/Fc, and a dielectric polymer blend layer of PMMA/PEO.

[0024] The preparation of the wire was carried out as in Example 1. In this example, the preparation of the single fibres necessitated the following steps: [0025] 1) The conductive support core is composed of a copper wire with a thickness of 50 micrometres. [0026] 2) The electrochromically active layer was created in the following manner: the copper core was co-extruded in an extruder together with a polymer blend, preformed by extrusion in granulometric pellets, by means of a double screw extruder, and containing 45% Polyvinil Butyral (PVB), 10% of Poly Ethylene Oxide (PEO), 40% of N-Methyl Pyrrolidone in which SWCNT in a proportion of 1 mg/ml, 2% of Ferrocene and 3% Ethyl Viologen were previously dispersed. The co-extrusion of the film took place hot, at the head temperature of 150° C. and an outlet temperature equal to 80° C., which generated a coating of 100 micrometers of electroactive polymer on the copper wire. [0027] 3) A dielectric polymer blend, created with a solution containing 50% Methyl methacrylate, 25% PEO, 25% Propylene Carbonate (PC). To this solution, Lithium Perchlorate (LiCIO4) was added in a concentration of 1 molar and 0.5% of the total mass of a radical initiator. [0028] The fibre produced from Stage 2 was dipped several times into the solution, keeping the extremities out, and then irradiated with UV until a 50-micron layer of dielectric polymeric film had formed on it. [0029] 4) The two portions of fibre, prepared as illustrated in the preceding steps, were intertwined together. [0030] 5) The intertwined fibres resulting from Step 4 were placed into a reactor, keeping the extremities out, in which Polyethylene glycol 1400 and the aliphatic diisocyanate 2,2,4-trimethyl-hexamethylene diisocyanatein (microdrops of 25 micrometres in diameter) were nebulized. [0031] The aforementioned components, reacting to form the urethane bond, covered the intertwined fibres with a transparent, insulating, mechanically resistant polyurethane. The average diameter of the fibre was found to be 0.6 mm. The wire produced in this manner is an electrochromic system that passes from transparency to an intense blue colour when powered with a voltage of 2 Volts.

Example 8

[0032] A wire thread formed of fibres with a conductive core and metal support, an electrochromically active layer of PVB/PEO/MWCNT/NMP/EV/Fc, and a dielectric polymer blend layer of PMMA/PEO. The example is analogous to Example 7, being different only for the fact that MWCNTs were used in the place of the SWCNTs.

Example 9

[0033] A wire thread formed of fibres with a conductive core and metal support, an electrochromically active layer of PVB/PEDOT:PSS/SWCNT/NMP, and a dielectric polymer blend layer of PMMA/PEO.

[0034] The thread was prepared in an analogous manner to that in Example 7, except for the fact that the electrochromic polymer blend to be extruded is formed of PVB-PEDOT:PSS-SWCNT and was prepared by modifying the procedure proposed by P. J. Bora et al. Materials Letters 252 (2019) 178-181. PEDOT:PSS was added to an ethanolic solution (absolute ethanol) of PVB at 35% by weight in a measure of 10% by weight, stirred constantly. After 1 hour of stirring a given volume of a suspension of carbon nanotubes (1 mg of nanotubes/1 mL of absolute ethanol) was added to the PVB-PEDOT: PSS solution, to have 1% by weight of nanotubes in the final blend. The blend thus obtained was stirred continuously for 3 hours. The blend was then air dried for 48 hours.

Example 10

[0035] A wire thread formed of fibres with a conductive support core of metal, an electrochromically active layer of PVB/PEDOT: PSS/MWCNT/NMP, and a dielectric polymer blend layer of PMMA/PEO. The example is analogous to Example 9, being different only for the fact that MWCNTs were used in the place of SWCNTs.

Example 11

[0036] A wire thread formed of fibres with a conductive support core of cellulose, coated in PEDOT: PSS, an electrochromically active layer of PMMA/PEO/SWCNT/NMP/EV/Fc, and a dielectric polymer blend layer of PMMA/PEO.

[0037] The system was created by using a cellulose thread as the core wire, which was coated with the conductive polymer PEDOT: PSS. The coating was created as in Example 1 by polymerizing the PEDOT: PSS in situ, using the oxidative polymerization procedure of the monomer 3,4-ethylenedioxythiophene (EDOT), according to the literature (Bayer AG, European Patent 440 957, 1991). The preparation of the wire was carried out through the following steps: [0038] 1) The supporting and conductive core was prepared by immersing the cellulose in an aqueous solution, consisting of poly acid (4-styrenesulfonate (PSS) and EDOT in the molar ratio 2.5, from 1% by weight of the oxidizing agent sodium persulfate (Na2S2O8) and 0.2% by weight of the catalyst FeSO4 7H2O. The oxidative polymerization was carried out under stirring at room temperature for 24 hours. The fibre thus obtained was subsequently washed in pure water, to remove the residual ions and then subsequently dehydrated. [0039] 2) An active electrochromic layer was made from a solution containing 50% of methyl methacrylate, 25% of PEO, 25% of Propylene Carbonate, and 1% of ETV. Lithium perchlorate (LiCIO4) was added to this solution in a 1 molar concentration, together with 0.5% of the total mass of a radical initiator. The fibre resulting from Step 1 was dipped several times into the solution, keeping the extremities out, and then irradiated with UV until a layer of 50 micrometres of dielectric polymeric film had formed on the fibre. [0040] 3) The fibre obtained from Step 2) was coated with a solid polymeric electrolyte, made similarly to as reported in Step 2) of Example 1. [0041] 4) The two portions of fibre, prepared as illustrated in the previous steps, were intertwined together. [0042] 5) The intertwined fibres from Step 4 were coated with an insulating polyurethane obtained in an analogous manner to as reported in Example 1. [0043] The wire thread thus produced is an electrochromic system, that passes from transparency to an intense blue colour when powered with a voltage of 2.5 Volts.

Example 12

[0044] A wire thread formed of fibres with a conductive support core of cellulose, coated with PEDOT: PSS/SWCNT (MWCNT), an electrochromically active layer of PEDOT: PSS/SWCNT, and a dielectric polymer blend layer of PMMA/PEO. The

[0045] example is analogous to Example 11, being different only for the fact that the electrochromically active layer is composed of PEDOT: PSS/SWCNT instead of PMMA/PEO/SWCNT/NMP/EV/Fc. The creation of the wire involved the same steps 1), 3), 4) and 5) given in Example 11, with the difference that in Step 1) in the aqueous solution of PSS and EDOT the carbon nanotubes in a concentration of 1 mg/mL were dispersed.

Example 13

[0046] A wire thread formed of fibres with a conductive support core of cellulose, coated with PEDOT: PSS/SWCNT, an electrochromically active layer of PMMA/PEO/SWCNT/NMP/EV/Fc, and a dielectric polymer blend layer of PMMA/PEO. The

[0047] Example is analogous to Example 11, being different only for the fact that the cellulose support was coated with a PEDOT blend of PEDOT: PSS/SWCN, created as in Example 12 (Step 1). Steps 2) and 5) of Example 11 were also repeated in this example.

Example 14

[0048] A wire thread formed of fibres with a conductive support core of cellulose, coated with SWCNT, an electrochromically active layer of PMMA/PEO/SWCNT/NMP/EV/Fc, and a dielectroc polymer blend layer of PMMA/PEO. The system was created by using a cellulose fibre as a central core, which was coated with SWCNTs. The creation of the wire was carried out through the following steps: [0049] 1) A conductive support layer, was created by slightly modifying the method proposed by Haisong Qi et al. (J. Mater. Chem. A, 2014, 2, 5541): the cellulose core fibre was immersed for 5 minutes in a homogenous aqueous suspension of 1% SWCNT (1 mg/mL) and 0.65% of the surfactant Brij76, keeping out the two extremities. The thread was subsequently air dried for 30 minutes. The dipping and dehydration process was repeated several times, until a normalized resistivity, not exceeding 5 kW cm-1 (which corresponds to about 250 S cm-1), was obtained along the length of the thread dehydrated under vacuum at 40° C. for 8 hours. [0050] Steps from 2) to 5) were analogous to Example 1.

Example 15

[0051] A wire thread formed of fibres with a conductive polyester support core, coated with PEDOT: PSS/SWCNT, an electrochromically active layer of PMMA/PEO/SWCNT/NMP/EV/Fc, and a dielectric polymer blend layer of PMMA/PEO.

[0052] The system was created by using as a central core a polyester fibre coated with a conductive and electrochromic blend, formed of the PEDOT: PSS polymer and of the SWCNTs. The creation of the wire was carried out by the following steps: [0053] 1) The conductive and supporting core was made as in Step 1) of Example 12. Steps from 2) to 5) were analogous to those of Example 1.

Example 16

[0054] A fabric in which the weft and warp are made up of the thread of Example 4.

[0055] 20 metres of the thread referred to in Example 4 were made. With these 10 spools, each with 1 metre of thread were made, and 1 spool with 10 metres of thread. The 10 spools with 1 metre of thread were substituted for the same number of warp threads of a 10 cm high ribbon made with a warp of 80 raffia threads of PP of 4500 dTex and a Monofilament weft of PP of 450 dTex of title, woven on a J.Muller NC 2/130 loom with a Cloth weave.

[0056] The new threads in the warp were placed in equally spaced positions. The spool with 10 metres of thread was used to feed the weft, with a density of 8 inserts per centimetre.

[0057] The electrical bonding of the extremities of the wires was carried out warp and weft with two copper conductors.

[0058] The fabric was powered by a battery capable of supplying a voltage of between 2.4V-3.6V.

[0059] The microvoltage regulator, equipped with Bluetooth connectivity, was placed between the battery and the fabric.

[0060] The voltage regulator was associated, through Bluetooth technology, to a Smartphone, on which a specific application was running.

[0061] Through the graphic interface of this application, it is possible to vary the voltage supplied to the fabric, in order to obtain the desired chromatic variation.