Conjugated polymers comprising 3,4-ethylenedioxythiophene and process for their preparation

Abstract

A conjugated polymer comprising 3, 4-ethylenedioxy thiophene having general formula (I): wherein: R1, R2, R3 and R4, equal to or different from each other, represent a hydrogen atom; or are selected from ester groups having general formula (II): wherein Rs is selected from C1-C20 alkyl groups, preferably C1-C15, more preferably is a C15 alkyl group, provided that at least two of R1, R2, R3 and R4 are selected from ester groups having general formula (II); preferably, R2 and R3, equal to each other, represent a hydrogen atom and R1 and R4, equal to each other, are selected from ester groups having general formula (II); - m is an integer ranging from 0 to 100, preferably ranging from 0 to 20; - n is an integer ranging from 10 to 100, preferably ranging from 15 to 20; - A is a monovalent sulfonate anion, optionally polymeric, preferably selected from trifluoromethanesulfonate, nonafluorobutanesulfonate, p-toluenesulfonate, poly(styrene sulfonate). The above-mentioned conjugated polymer having general formula (I) can be advantageously used in anticorrosive coatings of metal surfaces. Furthermore, the above-mentioned conjugated polymer having general formula (I) can be advantageously used in the field of organic electronics, sensors and actuators, as well as in the construction of battery electrodes. Furthermore, the above-mentioned conjugated polymer having general formula (I) can be advantageously used in 3D printing compositions.

Description

[0001] CONJUGATED POLYMERS COMPRISING 3,4-

[0002] ETHYLENEDIOXYTHIOPHENE AND PROCESS FOR THEIR PREPARATION

[0003] The present invention relates to conjugated polymers comprising 3,4- ethylenedioxythiophene.

[0004] More specifically, the present invention relates to a conjugated polymer comprising 3 ,4-ethylenedioxy thiophene having the specific general formula (I) below reported.

[0005] The above-mentioned conjugated polymer having general formula (I) can be advantageously used in anticorrosive coatings of metal surfaces. Furthermore, the above-mentioned conjugated polymer having general formula (I) can be advantageously used in the field of organic electronics, sensors and actuators, as well as in the construction of battery electrodes. Furthermore, the above-mentioned conjugated polymer having general formula (I) can be advantageously used in 3D printing compositions.

[0006] The present invention also relates to processes for the preparation of said conjugated polymer having general formula (I).

[0007] Another object of the present invention is an anticorrosive coating of metal surfaces comprising the above-mentioned conjugated polymer having general formula (I).

[0008] It is well known that metal corrosion is a very significant problem for the durability of structures and products that include metal parts with negative consequences for the environment and safety.

[0009] Anticorrosive coatings are generally classified according to the mechanisms by which they are able to protect metals from corrosion. The basic mechanisms of anticorrosive coatings are: the barrier effect, sacrificial inorganic protection (galvanic effect), the self-healing mechanism, and the inhibiting effect.

[0010] The barrier effect, a fundamental mechanism used by various anticorrosive coatings, involves the creation of a physical shield between the substrate material and corrosive agents. By forming said physical shield, the coating prevents the diffusion of moisture, oxygen and other corrosive substances, thus effectively isolating the substrate from the environment.

[0011] Another fundamental mechanism is sacrificial protection, often observed in anticorrosive coatings containing metals with a greater electrochemical potential than that of the underlying substrate. In the presence of corrosive agents, said coatings work by intentionally corroding the sacrificial metal layer. This process safeguards the substrate, as corrosive agents selectively attack the sacrificial layer. This mechanism is particularly advantageous when the structural integrity of the coating could be compromised, such as in the case of scratches or minor damage to the coating itself.

[0012] Other anticorrosive coatings act via a self-healing mechanism. These coatings contain additives or components that possess the ability to repair themselves when they suffer minor mechanical damage or scratches. When these coatings are damaged, the additives or components contained therein are activated, initiating a repair process within the affected region.

[0013] Anticorrosive coatings with an inhibiting effect are mainly applied to the substrate as primers because they produce their effect if their components can react with the metal. The anticorrosive mechanism of said coatings is based on the passivation of the substrate and the formation of a protective layer consisting of insoluble metal complexes that prevent the transport of aggressive species by acting as a barrier. Inhibiting components are generally slightly water-soluble inorganic salts such as, for example, phosphates, chromates, molybdates, nitrates, borates and silicates.

[0014] Anticorrosive coatings can be also classified according to their composition into organic, inorganic and metallic anticorrosive coatings.

[0015] Organic anticorrosive coatings are the most commonly used. They form a continuous film on the substrate, providing a physical barrier against corrosive agents. The thickness and composition of the coating can be adapted to specific requirements, offering flexibility in coating applications. In addition, organic anticorrosive coatings often exhibit excellent adhesion to the substrate, enhancing their protection.

[0016] Inorganic anticorrosive coatings, including ceramic anticorrosive coatings, are known for their high temperature resistance and hardness. These coatings are typically composed of oxides, carbides or nitrides. Inorganic anticorrosive coatings offer excellent resistance to chemical attack and can withstand harsh environments. Finally, inorganic anticorrosive coatings provide protection due to their chemical stability and ability to form stable oxide layers that act as barriers.

[0017] Metallic anticorrosive coatings provide protection through the mechanisms of cathodic protection (galvanic effect) or barrier effect. Metallic coatings that act by means of sacrificial inorganic protection (galvanic effect), such as zinc or aluminium anticorrosive coatings, have a greater electrochemical potential than the underlying metal, allowing them to selectively corrode while protecting the substrate. In contrast, metallic anticorrosive coatings, often composed of metals such as stainless steel or nickel alloys, act by means of a barrier effect, creating a physical barrier between the substrate and the corrosive environment and inhibit the transport of corrosive agents towards the substrate, thus reducing the corrosion rate.

[0018] Hybrid anticorrosive coatings combine the advantages of organic and inorganic anticorrosive coatings.

[0019] While the anticorrosive coatings known in the art above reported exhibit outstanding anticorrosive properties, they have application limitations and often pose environmental problems. For example, the elimination of hexavalent chromium and, in general, heavy metals (for example, lead, mercury) from both the formulation of coatings and coating processes is still an important issue for the anticorrosive coatings industry, particularly the aerospace industry. Industry and academic bodies have focused their efforts on developing inorganic anticorrosive coatings based on sol-gel technologies and hybrid inorganic-organic anticorrosive coatings such as, for example, nano-ceramic coatings using titanium, zirconium, silicates, rare earth metals and molybdate compounds, as more environmentally friendly alternatives. These inorganic coatings are generally prepared in highly diluted solutions, which means using large volumes of water. Therefore, the resulting residual water must undergo post-treatment before discharge to comply with the emission limit values for metals and other pollutants.

[0020] Organic anticorrosive coatings also present problems as they contain organic solvents as one of the main components of their formulation. In this regard, it is worth mentioning that the European community has recently started studying the control or limitation of emissions of volatile organic compounds (VOC), based on the need to develop new products that comply with these emissions and contain low levels of organic solvents. To solve this challenge, industrially applicable solutions will have to be industrialised. Furthermore, the substitution of hazardous materials, such as isocyanate, for producing polyurethane is still a major challenge for the anticorrosive coatings industry due to its consequences for human health.

[0021] Finally, in addition to the environmental problems outlined above, anticorrosive coatings may have certain application limitations such as, for example:

[0022] • anticorrosive coatings with an inhibiting effect are not applicable to immersed structures;

[0023] • anticorrosive coatings acting by means of sacrificial inorganic protection (galvanic effect) based on zinc silicates generally show poor adhesion to subsequent applications (for example, paints) with consequent “peeling” or “bubbling” phenomena when such applications are implemented;

[0024] • in splash-prone areas and atmospheric environments, damaged anticorrosive coatings with barrier effect offer insufficient protection against corrosion.

[0025] More information on the above-mentioned anticorrosive coatings can be found, for example, in Aljibori H. S. et al., "International Journal of Corrosion Scale Inhibition" (2023), Vol. 12, No. 4, pp. 1476-1520, DOI: 10.17675 / 2305-6894-2023-12- 4-6; Sprensen P. A. et al, "Journal of Coatings Technology and Research" (2009), Vol 6 (2), pp. 135-176, DOI 10.1007 / sl 1998-008-9144-2; Faccini M et al, "Applied Sciences" (2021), Vol. 11 (8), p. 3446, doi.org / 10.3390 / app 11083446.

[0026] The Applicant therefore set itself the problem of finding a polymer capable of overcoming the above-mentioned drawbacks and of providing longer-lasting and more effective protection when used in anticorrosive coatings of metal surfaces.

[0027] The Applicant has now found a polymer, more specifically a conjugated polymer comprising 3, 4-ethylenedioxy thiophene having the specific general formula (I) below reported, capable of overcoming the above-mentioned drawbacks. Said polymer has an innovative structure as it is synthesised from an enantiomerically pure, functionalised 3, 4-ethylenedioxy thiophene (EDOT) monomer with two ester groups on ethylene carbons in S configuration: these characteristics make it possible to obtain a polymer characterised by high hydrophobicity and the ability to rotate polarised light, together with the semiconductive / conductive properties common to poly (3,4- ethylenedioxythiophenes) (PEDOT s).

[0028] Thanks to its hydrophobicity and the fact that it can be reduced and oxidised by interfering with the electrochemical process of corrosion, the above-mentioned conjugated polymer is in fact able to: produce a barrier effect by forming a sufficiently compact polymer layer with a high contact angle (i.e. a contact angle > 90°), characteristic of a hydrophobic material which is able to hinder the metal’s contact with the aqueous matrix, which, in addition to itself promoting corrosion, can be the transport medium for other corrosive agents; provide anodic protection as the polymer coating has intrinsic redox state change properties that can act as a sacrificial anode; influence its conductive and redox properties due to the presence of monovalent sulfonate anions, as well as shielding the entry of additional anions into the coating, for example, chloride ions (Cl ), which are extremely aggressive corrosive agents.

[0029] Therefore, the object of the present invention is a conjugated polymer comprising 3 ,4-ethylenedioxy thiophene having general formula (I): m[A]- (I) wherein:

[0030] Ri , R2, R3 and R4, equal to or different from each other, represent a hydrogen atom; or are selected from ester groups having general formula (II): wherein R5 is selected from C1-C20 alkyl groups, preferably C1-C15, more preferably is a C 15 alkyl group, provided that at least two of Ri, R2, R3 and R4 are selected from ester groups having general formula (II); preferably, R2 and R3, equal to each other, represent a hydrogen atom and Ri and R4, equal to each other, are selected from ester groups having general formula (II); m is an integer ranging from 0 to 100, preferably ranging from 0 to 20; n is an integer ranging from 10 to 100, preferably ranging from 15 to 20;

[0031] A is a monovalent sulfonate anion, optionally polymeric, preferably selected from trifluoromethanesulfonate, nonafluorobutanesulfonate, p-toluenesulfonate, poly(styrene sulfonate).

[0032] For the purpose of the present description and of the following claims, the definitions of the numeric ranges always include the extremes unless specified otherwise.

[0033] For the purpose of the present description and of the following claims, the term “comprising” also includes the terms “which essentially consists of’ or “which consists of’.

[0034] In accordance with a preferred embodiment of the present invention, said conjugated polymer having general formula (I) is poly(((2S,3S)-2,3-dihydrothieno[3,4- b][l,4]dioxin-2,3-diyl)bis(methylene) dipalmitate) [P(EDOT-C16)], optionally containing monovalent sulfonate anions.

[0035] The present invention also relates to processes for the preparation of said conjugated polymer having general formula (I).

[0036] A first process relates to the preparation of said conjugated polymer having general formula (I) by direct arylation.

[0037] Consequently, an additional object of the present invention is a first process for the preparation of a conjugated polymer having general formula (I) comprising reacting at least one functionalised 3, 4-ethylenedioxy thiophene (EDOT) having general formula (III): wherein Ri, R2, R3 and R4, have the same meanings reported above with at least one dibrominated 3, 4-ethylenedioxy thiophene (EDOT) having general formula (IV): wherein Ri, R2, R3 and R4, have the same meanings reported above, in the presence of at least one weak organic base, at least one palladium-containing catalyst, at least one polar aprotic organic solvent and at least one weak organic acid.

[0038] In accordance with a preferred embodiment of the present invention, said functionalised 3, 4-ethylenedioxy thiophene (EDOT) having general formula (III) and said dibrominated 3, 4-ethylenedioxy thiophene (EDOT) having general formula (IV) can be used in a 1: 1 molar ratio.

[0039] It should be noted that said ratio allows the degree of polymerisation to be optimised in accordance with the Carothers equation.

[0040] In accordance with a preferred embodiment of the present invention, said weak organic base can be selected, for example, from: carboxylates of alkaline metals (e.g., sodium, potassium, cesium) or alkaline-earth metals (e.g., magnesium, calcium) such as, for example, potassium acetate, sodium acetate, cesium acetate, magnesium acetate, calcium acetate, potassium propionate, sodium propionate, cesium propionate, magnesium propionate, calcium propionate, or mixtures thereof; carbonates of alkaline metals (e.g., lithium, sodium, potassium, cesium) or alkaline-earth metals (e.g., magnesium, calcium) such as, for example, lithium carbonate, potassium carbonate, sodium carbonate, cesium carbonate, magnesium carbonate, calcium carbonate, or mixtures thereof; bicarbonates of alkaline metals (e.g., lithium, sodium, potassium, cesium) or alkaline-earth metals (e.g., magnesium, calcium) such as, for example, lithium bicarbonate, potassium bicarbonate, sodium bicarbonate, cesium bicarbonate, magnesium bicarbonate, calcium bicarbonate, or mixtures thereof; or mixtures thereof. Said weak organic base is, preferably, potassium carbonate.

[0041] In accordance with a preferred embodiment of the present invention, said functionalised 3, 4-ethylenedioxy thiophene (EDOT) having general formula (III) and said weak organic base can be used in molar ratios ranging from 1 :2.1 to 1 :20, preferably ranging from 1:2.2 to 1:4.

[0042] In accordance with a preferred embodiment of the present invention, said palladium-containing catalyst can be selected, for example, from: palladium compounds in oxidation state (0) or (II) such as palladium(II) chloride [PdCh], palladium(II) acetate [Pd(OAc)2], bis(dibenzylidene)palladium(O) [Pd(dba)2 wherein dba = C6H5CH=CHCOCH=CHC6HS], bis(acetonitrile)palladium(II) chloride [Pd(CH3CN)2C12], or mixtures thereof. Said palladium-containing catalyst is preferably, palladium(II) acetate [Pd(OAc)2].

[0043] In accordance with a preferred embodiment of the present invention, said functionalised 3, 4-ethylenedioxy thiophene (EDOT) having general formula (III) and said palladium-containing catalyst can be used in molar ratios ranging from 100:0.1 to 100: 10, preferably ranging from 100:0.4 to 100:5.

[0044] In accordance with a preferred embodiment of the present invention, said polar aprotic organic solvent can be selected, for example, from: A, A-di methyl acetamide (DMAc), dimethyl sulfoxide (DMSO), A-mcthylpyrrolidonc (NMP), dimethylformamide (DMF), or mixtures thereof. Said polar aprotic organic solvent is, preferably, N, A-di methyl acetamide (DMAc).

[0045] In accordance with a preferred embodiment of the present invention, said functionalised 3, 4-ethylenedioxy thiophene (EDOT) having general formula (III) can be used in said polar aprotic organic solvent in an amount such as to have a molar concentration in said solvent ranging from 0.05 M to 0.5 M, preferably ranging from 0.08 M to 0.2 M.

[0046] In accordance with a preferred embodiment of the present invention, said weak organic acid can be selected, for example, from acetic acid, propionic acid, pivalic acid, zso-butyl acid, or mixtures thereof. Said weak organic acid is, preferably, pivalic acid.

[0047] In accordance with a preferred embodiment of the present invention, said functionalised 3, 4-ethylenedioxy thiophene (EDOT) having general formula (III) and said weak organic acid can be used in molar ratios ranging from 100: 10 to 100:50, preferably ranging from 100: 15 to 100:40.

[0048] In accordance with a preferred embodiment of the present invention, said process can be carried out at a temperature ranging from 80°C to 170°C, preferably ranging from 100°C to 150°C.

[0049] In accordance with a preferred embodiment of the present invention, said process can be carried out for a time ranging from 30 minutes to 36 hours, preferably ranging from 1 hour to 30 hours.

[0050] Generally, at the end of the above-mentioned process, the resulting mixture is cooled to room temperature (25 °C), precipitated with an organic solvent (for example, methanol), filtered and purified through a first Soxhlet extraction in various organic solvents (for example, methanol, acetone, hexane) and a second Soxhlet extraction in chloroform or toluene, obtaining a solution containing the polymer that is subsequently dried by evaporation (for example, in a rotovapor).

[0051] In the case of the conjugated polymer having general formula (I) obtained by means of the above-mentioned direct arylation process, the monovalent sulfonate anion can be introduced by processes known in the art such as, for example, mixing the polymer and a compound containing a monovalent sulfonate anion, or deposition of a solution of a compound containing a monovalent sulfonate anion on a polymer film, or diffusion through the polymer film of a compound containing a sulfonate anion by sublimation thereof. More details relative to said processes can be found, for example, in Wang S. et al., "Progress in Polymer Science" (2022), 129, 101548, DOI: 10.1016 / j.progpolymsci.2022.101548.

[0052] A second process relates to the preparation of said conjugated polymer having general formula (I) by oxidative polymerisation.

[0053] Consequently, an additional object of the present invention is a second process for the preparation of a conjugated polymer having general formula (I) comprising reacting at least one functionalised 3, 4-ethylenedioxy thiophene (EDOT) having general formula (III): wherein Ri, R2, R3 and R4, have the same meanings reported above with at least one compound containing a monovalent sulfonate anion, optionally polymeric, in the presence of at least one chlorinated organic solvent.

[0054] In accordance with a preferred embodiment of the present invention, in said second process, said compound containing a monovalent, optionally polymeric, sulfonate anion can be selected, for example, from iron(III) p-toluenesulfonate hexahydrate, sodium poly (styrene sulfonate) (Na-PSS), sodium trifluoromethanesulfonate, sodium nonafluorobutanesulfonate, or mixtures thereof. Said compound containing a monovalent sulfonate anion is, preferably, iron(III) p- toluenesulfonate hexahydrate.

[0055] In accordance with a preferred embodiment of the present invention, in said second process, said functionalised 3, 4-ethylenedioxy thiophene (EDOT) having general formula (III) and said compound containing a monovalent, optionally polymeric, sulfonate anion can be used in molar ratios ranging from 1: 1 to 1:20, preferably ranging from 1: 1.5 to 1: 15.

[0056] In accordance with a preferred embodiment of the present invention, said chlorinated organic solvent can be selected, for example, from dichloromethane, chloroform, ethylene dichloride, carbon tetrachloride, or mixtures thereof. Said chlorinated organic solvent is, preferably, chloroform.

[0057] In accordance with a preferred embodiment of the present invention, said functionalised 3, 4-ethylenedioxy thiophene (EDOT) having general formula (III) can be used in said chlorinated organic solvent in an amount such as to have a molar concentration in said solvent ranging from 0.01 M to 0.5 M, preferably ranging from 0.03 M to 0.2 M.

[0058] In accordance with a preferred embodiment of the present invention, said second process can be carried out at a temperature ranging from 10°C to 100°C, preferably ranging from 20°C to 80°C.

[0059] In accordance with a preferred embodiment of the present invention, said second process can be carried out for a time ranging from 2 hours to 15 days, preferably ranging from 8 hours to 10 days.

[0060] The above-mentioned compounds having general formula (III) and (IV) can be obtained by processes known in the art: further details on their preparation can be found in the following examples. As already mentioned, the above-mentioned conjugated polymer comprising 3,4- ethylenedioxythiophene having general formula (I) can be advantageously used in anticorrosive coatings of metal surfaces.

[0061] It is also a further object of the present invention an anticorrosive coating of metal surfaces comprising at least one conjugated polymer comprising 3,4- ethylenedioxy thiophene having general formula (I).

[0062] In order to better understand the present invention and to put it into practice, some illustrative and non-limiting examples thereof are reported below.

[0063] The analysis and the characterization methodologies reported below were used.

[0064] 1H-HMR and13C-HMR spectra

[0065] The1H-HMR and13C-HMR spectra were recorded using a Bruker Avance 400 model nuclear magnetic resonance spectrometer. The1H-NMR and13C-NMR spectral data refer to deuterated chloroform (CDCh): 8 = 7.26 ppm for ’ H-NMR and 8 = 77.00 ppm for13C-NMR.

[0066] For this purpose, polymer solutions of the polymers obtained in the following examples in deuterated chloroform, at concentrations of 10% by weight with respect to the total weight of the polymer solution, were used.

[0067] Mass spectra

[0068] The mass spectra of the polymers obtained in the following examples were carried out with an LCQ Fleet system Thermo Scientific ion trap ESI source mass spectrometer (Surveyor MS Pump / Autosampler / PDA Detector), operating under the following conditions.

[0069] Tune parameters positive polarity: sheath gas flow rate: 10 arb ("arbitrary units"); ion spray voltage: 5 kV; capillary voltage: 25 V; capillary temperature: 275°C; tube lens: 95 V; mass range: 150 Da - 2000 Da.

[0070] The spectrometer is connected to a computer equipped with the Thermo Scientific Xcalibur 2.2 software package.

[0071] Determination of the molecular weight The determination of the molecular weight of the polymers obtained in the following examples was carried out using GPC (“Gel Permeation Chromatography”) using a Waters chromatography system equipped with a refractive index detector, a set of two universal columns (Styragel 4E and 5E) in series. Tetrahydrofuran (THF) stabilised with 250 ppm 2,6-di-tert-butyl-4-methylphenol (BHT) was used as the mobile phase (1 mL / min; 40°C).

[0072] The polymer solutions were pre-filtered using 0.4 pm polytetrafluoroethylene (PTFE) filters and then injected into the column. The distribution of molecular weights (Mw, Mn) and the Polydispersity Index (PDI) were obtained by processing with “Breeze” software, using 12 low-polydispersity polystyrene standards for the calibration curve (Fluka kit).

[0073] Polymer film deposition

[0074] To carry out the static contact angle measurements, solutions of the polymers obtained in the following examples were prepared, at a known concentration, in chloroform or toluene.

[0075] Solutions were prepared in chloroform with a concentration equal to: 0.3 mg / mE, 3 mg / mL, 10 mg / mL and 30 mg / mL.

[0076] Solutions were prepared in toluene with a concentration equal to: 1 mg / mL, 3 mg / mL, 10 mg / mL and 30 mg / mL.

[0077] The above-mentioned solutions were deposited on a glass or steel substrate by “drop casting” or “spin coating”.

[0078] For spin coating deposition conditions, on a glass substrate, the volume of solution deposited was 50 pL. After deposition, the substrate was rotated as follows: for solutions in chloroform at a concentration equal to 0.3 mg / mL and 3 mg / mL, a rotation speed equal to 100 rpm and an acceleration equal to 3 rpm / s for 60 s were used; for solutions in chloroform at a concentration equal to 10 mg / mL, a rotation speed equal to 150 rpm and an acceleration equal to 5 rpm / s for 60 s were used; for solutions in chloroform at a concentration of 30 mg / mL, a rotation speed equal to 550 rpm and an acceleration equal to 3 rpm / s for 180 s were used; for solutions in toluene at a concentration equal to 1 mg / mL and 3 mg / mL, a rotation speed equal to 100 rpm and an acceleration equal to 5 rpm / s for 360 s were used; for solutions in toluene at a concentration equal to 10 mg / mL, a rotation speed equal to 120 rpm and an acceleration equal to 5 rpm / s for 360 s were used; for solutions in toluene at a concentration equal to 30 mg / mL, a rotation speed equal to 150 rpm and an acceleration equal to 5 rpm / s for 180 s were used.

[0079] With regard to the drop casting deposition conditions, on a steel substrate, the volume of solution deposited was 25 pL: for this purpose, the polymer solution in toluene at a concentration equal to 30 mg / mL was deposited on the steel substrate by means of a micropipette and allowed to air dry.

[0080] Absorption spectra

[0081] The absorption spectra, in solution, in the ultraviolet and visible region (UV-Vis) (250 nm - 800 nm) of the polymers obtained in the following examples, were acquired in transmission using a JASCO V-55 spectrophotometer using polymer solutions in chloroform with concentrations equal to 0.16 mg / mL.

[0082] Absorption spectra were also acquired, on polymer films on a glass substrate, in the 300 nm - 1800 nm range using a Varian Cary 6000i spectrophotometer. For this purpose, solutions of the polymers obtained in the following examples were used in chloroform at concentrations equal to 0.3 mg / mL, 3 mg / mL, 10 mg / mL and 30 mg / mL, operating under the conditions described above.

[0083] Fluorescence spectra

[0084] The fluorescence spectra of the polymer solutions of the polymers obtained in the following examples, in chloroform at concentrations equal to 0.2 mg / mL, were acquired using a Horiba Jobin Yvon Fluorolog 3 spectrofluorometer, operating in front-face configuration. To obtain the emission spectrum, the wavelength (Xem) of the maximum peak in absorbance equal to 545 nm was selected, while to obtain the excitation spectrum, the wavelength (XeCC) of the maximum peak in the emission spectrum equal to 600 nm was selected.

[0085] Cyclic voltammetry

[0086] The cyclic voltammetry (CV) measurements were performed with an Amel model 4330 module equipped with a standard 25 mL electrochemical cell with three electrodes. In the measurements carried out, an Ag / Ag+pseudo reference electrode was used as the reference electrode, a platinum wire as the counter electrode and a glassy graphite electrode as the working electrode. The polymer sample to be analysed was dissolved in chloroform at a concentration equal to 2 mg / mL and, subsequently, two aliquots of 3 ptl were placed by dropping with a calibrated micropipette on the working electrode to form a film that was left to dry at room temperature (25 °C). The electrodes were immersed in a 0.1 M electrolyte solution of tetrabutylammonium hexafluorophosphate (TBAPFe) in acetonitrile (HPLC grade 99%) recrystallised three times from ethanol. The sample was then subjected to a cyclic potential in the form of a triangular wave with a scan rate equal to 50 mV / s. At the same time, as a function of the applied potential difference, the current, which signals the occurrence of oxidation or reduction reactions of the present species, was monitored. 25 voltammetric cycles were performed for each deposition, a method known in the literature as “break-in”.

[0087] The oxidation process corresponds to the removal of an electron from HOMO, while the reduction cycle corresponds to the introduction of an electron into LUMO. The potentials of formation of the radical cation and radical anion were derived from the value of the peak onset (Eonset), which is caused by molecules and / or chain segments with (EHOMO)-(ELUMO) levels closer to the edges of the bands. The electrochemical potentials and those relating to the electronic levels can be correlated if both refer to the vacuum. For this purpose, the potential of ferrocene in vacuum, known in the literature and equal to -4.8 eV, was taken as a reference. The inter-solvent redox pair ferrocene / ferrocinium (Fc / Fc+) was selected because it has an oxide-reduction potential independent of the working solvent.

[0088] Rotation of polarised light

[0089] The rotational power, indicated as [oc]20D, was measured using the JASCO P-2000 Polarimeter on both monomers and polymers obtained in the following examples.

[0090] Circular dichroism

[0091] The circular dichroism was measured on solutions of the polymers obtained in the following examples in chloroform with concentrations equal to 0.35 mg / mL using a JASCO 1500 spectrophotometer.

[0092] EXAMPLE 1

[0093] Synthesis of the monomer ((2S,3S)-2,3-dihydrothienor3,4-biri,41dioxin-2,3-diyl)bis- (methylene)dipalmitate (EDOT-C 16)

[0094] After removing the air via three vacuum / nitrogen cycles, the following were added to a 25 mL two-neck flask, equipped with magnetic stirring, bubble cooling tube and nitrogen inlet: 6.5 mL of dimethylformamide (DMF) (Sigma Aldrich) and, in order, 2R,3R-2,3-bis(bromomethyl)-2,3-dihydrothieno[3,4-b][l,4]-dioxin [synthesised as reported by Martinelli A. et al., in The Journal of Organic chemistry (2024), Vol. 89(6), pp. 4237-443, in “Supporting Information”] (302.4 mg; 0.922 mmoles), palmitic acid (Sigma Aldrich) (710.2 mg; 2.77 mmoles) and potassium carbonate (K2CO3) (Sigma Aldrich) (438.0 mg, 3.17 mmoles): the obtained reaction mixture was kept, in a nitrogen atmosphere, at 100°C, under stirring (400 rpm). The reaction was followed by thin layer chromatography (TLC) (eluent: n-hcxanc (Sigma Aldrich) / ethyl acetate (Sigma Aldrich) at a ratio of 9: 1 v / v) and was shown to be complete after 16 hours. The obtained reaction mixture was allowed to cool spontaneously to room temperature (25 °C) and, after the addition of 5 mL of brine, was extracted with dichloromethane (3 x 50 mL) and the organic phase (obtained by combining the three organic phases) was dried on sodium sulphate (NaiSCL) (Sigma Aldrich). After removal of the solvent by rotavapor, the resulting solid residue was purified by elution on a silica gel chromatography column [eluent: n-hcxanc (Sigma Aldrich) / dichloromethane (Sigma Aldrich) at a ratio of 9 / 1 v / v), yielding 335.7 mg (0.494 mmoles) of ((2S,3S)-2,3-dihydrothieno[3,4- b][l,4]dioxin-2,3-diyl)bis-(methylene)-dipalmitate (yield = 54%).

[0095] The monomer obtained was subjected to the following characterisations as described above:

[0096] ’ H-NMR (200 MHz, CDCI3) 5 6.38 (s, 2H); 4.46 - 4.35 (m, 2H); 4.35 - 4.25 (m, 4H); 2.34 (t, J = 7.5 Hz, 4H); 1.68 - 1.56 (m, 4H); 1.25 (s, 48H); 0.94 - 0.82 (m, 6H);

[0097] 13C-NMR (100 MHz, CDC13, 5): 173.2; 140.2; 100.2; 72.0; 62.1; 33.9; 31.8; 30.8; 29.6; 29.5; 29.5; 29.2; 29.1; 29.0; 24.7; 22.6; 14.0;

[0098] DEP-MS (El), m / z: 678.8 [M]+;

[0099] [<Z]20D = -27.1 (c 0.68, DCM); UV-Vis (dichloromethane): Xmax (a) = 257 nm.

[0100] EXAMPLE 2

[0101] Synthesis of the monomer ((2S,3S)-5,7-dibromo-2,3-dihydrothienor3,4-bllT,4]dioxin-

[0102] 2,3-diyl)bis-(methylene)dipalmitate (EDOT-C16-Br2)

[0103] After removing the air via three vacuum- nitrogen cycles, under a nitrogen atmosphere, the following were added to a 10 mL Schlenk tube equipped with a magnetic stirrer: the monomer ((2S,3S)-2,3-dihydrothieno[3,4-b][l,4]dioxin-2,3- diyl)bis-(methylene)-dipalmitate (EDOT-C16) obtained in Example 1 (30 mg, 0.044 mmol) dissolved in 4 mL of anhydrous tetrahydrofuran (THF) (Sigma Aldrich) previously distilled in the presence of metallic sodium. The Schlenk tube was then immersed in an ice and water bath and A-bromosuccinimide (NBS) (Fluorochem), previously recrystallised from water (17 mg, 0.96 mmol), was added under nitrogen flow. After 10 minutes, the flask was removed from the bath, and the temperature was allowed to rise spontaneously to room temperature (25°C): the whole was left under stirring (400 rpm), at room temperature (25 °C), for 18 hours. The reaction was followed by thin layer chromatography (TLC) (eluent: n-hcxanc (Sigma Aldrich) / ethyl acetate (Sigma Aldrich) at a ratio of 9: 1 v / v) and was shown to be complete after 18 hours.

[0104] The obtained reaction mixture was dried using a rotavapor and the solid residue obtained was filtered through a so-called “silica plug”. For this purpose, silica (Sigma Aldrich) was poured inside a filter funnel and conditioned by wetting it with 200 mL of pure hexane (Sigma Aldrich): subsequently, the solid residue was placed on the surface and was purified by pouring over it an eluent mixture of n-hcxanc (Sigma Aldrich) / ethyl acetate (Sigma Aldrich) at a ratio of 10: 1 v / v, checking the end of filtration by thin layer chromatography (TLC) with silica gel and an eluent mixture of n-hexane (Sigma Aldrich) / ethyl acetate (Sigma Aldrich) at a ratio of 9: 1 v / v.

[0105] The collected eluent phase was dried in a rotavapor, resulting in 27.1 mg (0.32 mmol) of the monomer ((2S,3S)-5,7-dibromo-2,3-dihydrothieno[3,4-b][l,4]dioxin-2,3- diyl)bis(methylene)dipalmitate (EDOT-C16-Br2) (73% yield).

[0106] The monomer obtained was subjected to the following characterisations as described above:

[0107] ’ H NMR (200 MHz, CDCI3) 5 4.37 (s, 6H); 2.34 (t, 4H); 1.64 (m, 4H); 1.25 (s, 48H); 0.95 - 0.80 (m, 6H);

[0108] 13C NMR (101 MHz, CDCI3) 5 220.61; 185.83; 133.55; 124.80; 124.48; 124.17; 119.89; 109.22; 81.46; 79.39; 77.16; 77.15; 77.12; 77.08; 76.92; 76.83; 76.72; 76.57; 72.29; 70.15; 61.58;

[0109] MS-ESI, m / z = 837.02 [M]+.

[0110] EXAMPLE 3

[0111] Synthesis of the poly(((2S,3S)-2,3-dihydrothienor3,4-bllT,4]dioxin-2,3- diyl)bis(methylene) dipalmitate) rP(EDOT-C16)1 by direct arylation

[0112] The following were added, in order, to a 10 mL Schlenk tube, equipped with a magnetic stirrer, after removing the air via three vacuum-nitrogen cycles, under vigorous nitrogen flow: monomer ((2S,3S)-5,7-dibromo-2,3-dihydrothieno[3,4-b][l,4]dioxin- 2,3-diyl)bis(methylene)dipalmitate (EDOT-C16-Br2) (159.6 mg, 0.191 mmoles) obtained in Example 2, monomer ((2S,3S)-2,3-dihydrothieno[3,4-b][l,4]dioxin-2,3- diyl)bis-(methylene)dipalmitate (EDOT-C16) (130.3 mg, 0.192 mmol) obtained in Example 1, palladium(II) acetate [Pd(OAc)2] (Sigma Aldrich) (0.9 mg, 0.004 mmol), pivalic acid (PivOH) (Alfa Aesar) (5.8 mg, 0.057 mmol) and potassium carbonate (K2CO3) (Sigma Aldrich) (66.2 mg, 0.48 mmol), and 2 mL of anhydrous A,A- dimethylacetamide (DMAc) (99.8% purity; Sigma Aldrich). The obtained reaction mixture was kept at room temperature (25°C), for two minutes, under stirring (400 rpm). Subsequently, the Schlenk tube was immersed in an oil bath previously heated to 140°C and kept at this temperature for 24 hours.

[0113] Subsequently, the reaction mixture was allowed to cool spontaneously to room temperature (25°C), poured into methanol (100 mL) and kept, under stirring (300 rpm), at said temperature, for 1 hour. The obtained precipitated solid residue was recovered by filtration, purified by Soxhlet extraction in methanol (125 mL), acetone (125 mL) and hexane (125 mL) and finally recovered from the Soxhlet by chloroform (125 mL) resulting in a dark purple solution: the extraction time corresponding to each solvent was 24 hours.

[0114] The solution in chloroform was dried in a rotavapor obtaining 167.3 mg of a dark purple powder with brownish reflections when illuminated by light corresponding to poly(((2S,3S)-2,3-dihydrothieno[3,4-b][l,4]dioxin-2,3-diyl)bis(methylene) dipalmitate) [P(EDOT-C16)] (yield = 58%).

[0115] The polymer obtained was subjected to the following characterisations as described above:

[0116] ’ H NMR (400 MHz, CDC13) 5 4.87 - 4.2 (br, m), 2.57 - 2.21 (br, m), 1.86 (br, s), 1.63 (br, s), 1.25 (br, s), 0.88 (br, s).

[0117] GPC [in tetrahydrofuran (THF); 40°C]: Mn= 6977 Da; Mw= 8828 Da; PDI = 1.27; UV-Vis (chloroform): kabsmax (s) = 545 nm, AabsIII,ll(s) = 315 nm (in solution); kabsmax (a) 552 nm (in film);

[0118] Fluorescence (chloroform): X.exCmax = 531 nm; X.emmax = 609 nm;

[0119] Cyclic voltammetry (CV): Ered= 540 mV; Eox= 1045 mV (in TBAPFe 0.1 M in acetonitrile vs. Ag / Ag+pseudoreference).

[0120] Figure 1 shows the circular dichroism [the x axis shows the wavelength in nm; the y axis shows the circular dichroism (DC) expressed in mdeg].

[0121] EXAMPLE 4

[0122] Contact angle measurement

[0123] The static contact angle was measured using the KSV CAM200 instrument, using the sessile drop method.

[0124] Chloroform and toluene solutions of the polymer obtained in Example 3 were prepared at increasing concentrations of 0.3 mg / mL, 3 mg / mL, 10 mg / mL and 30 mg / mL: the obtained solutions were deposited by spin coating (chloroform solutions) on a glass slide (dimensions 2.2 cm x 2.2 cm) and by drop casting (toluene solutions) on a steel specimen (2 cm x 2 cm) (30 mg / mL), working as described above.

[0125] A 5 pL drop of water was deposited on the resulting films using an automatic dispenser. For comparison purposes, a drop of water was deposited on a glass slide or on a steel specimen without the polymer film (white).

[0126] The static contact angle values are given in:

[0127] Figure 2: static contact angle from chloroform solutions on the glass slide (the x axis shows the concentration in mg / mL; the y axis shows the contact angle in °);

[0128] Figure 3: static contact angle from toluene solutions on the steel specimen (the x axis shows the concentration in mg / mL; the y axis shows the contact angle in °).

[0129] For reference purposes, the exact value of the static contact angle for the solution at a concentration of 30 mg / mL in toluene on a steel test specimen was 109.07+4.43°.

Claims

CLAIMS1. Conjugated polymer comprising 3, 4-ethylenedioxy thiophene having general formula (I): m[A]- (I)wherein:Ri , R2, R3 and R4, equal to or different from each other, represent a hydrogen atom; or are selected from ester groups having general formula (II):wherein R5 is selected from C1-C20 alkyl groups, preferably C1-C15, more preferably is a C 15 alkyl group, provided that at least two of Ri, R2, R3 and R4 are selected from ester groups having general formula (II); preferably, R2 and R3, equal to each other, represent a hydrogen atom and Ri and R4, equal to each other, are selected from ester groups having general formula (II); m is an integer ranging from 0 to 100, preferably ranging from 0 to 20; n is an integer ranging from 10 to 100, preferably ranging from 15 to 20;A is a monovalent sulfonate anion, optionally polymeric, preferably selected from trifluoromethanesulfonate, nonafluorobutanesulfonate, p-toluenesulfonate, poly(styrene sulfonate).

2. Conjugated polymer comprising 3, 4-ethylenedioxy thiophene having general formula (I) according to claim 1, wherein said conjugated polymer is poly(((2S,3S)-2,3- dihydrothieno [3 ,4-b] [ 1 ,4] dioxin-2,3 -diyl)bis(methylene) dipalmitate) [P(EDOT -C 16)] , optionally containing monovalent sulfonate anions.

3. Process for the preparation of a conjugated polymer having general formula (I) according to claim 1 or 2, comprising reacting at least one functionalized 3,4-ethylenedioxy thiophene (EDOT) having general formula (III):wherein Ri, R2, R3 and R4, have the same meanings as reported above with at least one dibrominated 3, 4-ethylenedioxy thiophene (EDOT) having general formula (IV):wherein Ri, R2, R3 and R4, have the same meanings as reported above, in the presence of at least one weak organic base, at least one palladium-containing catalyst, at least one polar aprotic organic solvent and at least one weak organic acid.

4. Process for the preparation of a conjugated polymer having general formula (I) according to claim 3, wherein said functionalized 3, 4-ethylenedioxy thiophene (EDOT) having general formula (III) and said dibrominated 3, 4-ethylenedioxy thiophene (EDOT) having general formula (IV) are used in a 1: 1 molar ratio.

5. Process for the preparation of a conjugated polymer having general formula (I) according to claim 3 or 4, wherein said weak organic base is selected from: carboxylates of alkali or alkaline-earth metals such as potassium acetate, sodium acetate, cesium acetate, magnesium acetate, calcium acetate, potassium propionate, sodium propionate, cesium propionate, magnesium propionate, calcium propionate, or mixtures thereof; carbonates of alkali or alkaline-earth metals such as lithium carbonate, potassium carbonate, sodium carbonate, cesium carbonate, magnesium carbonate, calcium carbonate, or mixtures thereof; bicarbonates of alkali or alkaline-earth metals such as lithium bicarbonate, potassium bicarbonate, sodium bicarbonate, cesium bicarbonate, magnesium bicarbonate, calcium bicarbonate, or mixtures thereof; or mixtures thereof;preferably potassium carbonate.

6. Process for the preparation of a conjugated polymer having general formula (I) according to any one of claims 3 to 5, wherein said functionalized 3,4- ethylenedioxythiophene (EDOT) having general formula (III) and said weak organic base are used in molar ratios ranging from 1:2.1 to 1:20, preferably ranging from 1:2.2 to 1:4.

7. Process for the preparation of a conjugated polymer having general formula (I) according to any one of claims 3 to 6, wherein said palladium-containing catalyst is selected from: palladium compounds in oxidation state (0) or (II) such as palladium(II) chloride [PdCh], palladium(II) acetate [Pd(OAc)2], bis(dibenzylidene)palladium(O) [Pd(dba)2 wherein dba = C6H5CH=CHCOCH=CHC6Hs], bis(acetonitrile)palladium(II) chloride [Pd(CH3CN)2C12], or mixtures thereof; preferably it is palladium(II) acetate [Pd(OAc)2].

8. Process for the preparation of a conjugated polymer having general formula (I) according to any one of claims 3 to 7, wherein said functionalized 3,4- ethylenedioxythiophene (EDOT) having general formula (III) and said palladiumcontaining catalyst are used in molar ratios ranging from 100:0.1 to 100: 10, preferably ranging from 100:0.4 to 100:5.

9. Process for the preparation of a conjugated polymer having general formula (I) according to any one of claims 3 to 8, wherein said polar aprotic organic solvent is selected from: A,A-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), N- methylpyrrolidone (NMP), dimethylformamide (DMF), or mixtures thereof; preferably it is A,A-dimethylacetamide (DMAc).

10. Process for the preparation of a conjugated polymer having general formula (I) according to any one of claims 3 to 9, wherein said functionalized 3,4- ethylenedioxythiophene (EDOT) having general formula (III) is used in said polar aprotic organic solvent in an amount such as to have a molar concentration in said solvent ranging from 0.05 M to 0.5 M, preferably ranging from 0.08 M to 0.2 M.

11. Process for the preparation of a conjugated polymer having general formula (I) according to any one of claims 3 to 10, wherein said weak organic acid is selected from acetic acid, propionic acid, pivalic acid, zso-butyl acid, or mixtures thereof; preferably it is pivalic acid.

12. Process for the preparation of a conjugated polymer having general formula (I) according to any one of claims 3 to 11, wherein said functionalized 3,4- ethylenedioxythiophene (EDOT) having general formula (III) and said weak organic acid are used in molar ratios ranging from 100: 10 to 100:50, preferably ranging from 100: 15 to 100:40.

13. Process for the preparation of a conjugated polymer having general formula (I) according to any one of claims 3 to 12, wherein said process: is carried out at a temperature ranging from 80°C to 170°C, preferably ranginmg from 100°C to 150°C; and / or for a time ranging from 30 minutes to 36 hours, preferably ranging from 1 hour to 30 hours.

14. Process for the preparation of a conjugated polymer having general formula (I) comprising reacting at least one functionalized 3, 4-ethylenedioxy thiophene (EDOT) having general formula (III):wherein Ri, R2, R3 and R4, have the same meanings as reported above with at least one compound containing a monovalent sulfonate anion, optionally polymeric, in the presence of at least one chlorinated organic solvent.

15. Process for the preparation of a conjugated polymer having general formula (I) according to claim 14, wherein said compound containing a monovalent sulfonate anion, optionally polymeric, is selected from iron(III) p-toluenesulfonate hexahydrate, sodium poly(styrene sulfonate) (Na-PSS), sodium trifluoromethanesulfonate, sodium nonafluorobutanesulfonate, or mixtures thereof; preferably, it is iron(III) p- toluenesulfonate hexahydrate.

16. Process for the preparation of a conjugated polymer having general formula (I) according to claim 14 or 15, wherein said functionalized 3, 4-ethylenedioxy thiophene (EDOT) having general formula (III) and said compound containing a monovalentsulfonate anion, optionally polymeric, are used in molar ratios ranging from 1: 1 to 1:20, preferably ranging from 1: 1.5 to 1: 15.

17. Process for the preparation of a conjugated polymer having general formula (I) according to any one of claims 14 to 16, wherein said chlorinated organic solvent is selected from dichloromethane, chloroform, ethylene dichloride, carbon tetrachloride, or mixtures thereof; preferably it is chloroform.

18. Process for the preparation of a conjugated polymer having general formula (I) according to any one of claims 14 to 17, wherein said functionalized 3,4- ethylenedioxythiophene (EDOT) having general formula (III) is used in said chlorinated organic solvent in an amount such as to have a molar concentration in said solvent ranging from 0.01 M to 0.5 M, preferably ranging from 0.03 M to 0.2 M.

19. Process for the preparation of a conjugated polymer having general formula (I) according to any one of claims 14 to 18, wherein said process is carried out: at a temperature ranging from 10°C to 100°C, preferably ranging from 20°C to 80°C; and / or for a time ranging from 2 hours to 15 days, preferably ranging from 8 hours to 10 days.

20. Anticorrosive coating of metal surfaces comprising at least one conjugated polymer comprising 3, 4-ethylenedioxy thiophene having general formula (I) of any one of claims 1 to 19.

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