Synthesis process of myrcene homopolymer

Description

DESCRIPTION Attached to a patent application for an INDUSTRIAL INVENTION having by title “Synthetic process of myrcene homopolymer” In the name: PROMETEON TIRE GROUP SRL Viale Sarca, 336 20126 MILAN MI UNIVERSITY OF INSUBRIA Via Ravasi, 2 21100 VARESE VA ******* TECHNICAL FIELD The present invention relates to a process for the preparation of an elastomeric homopolymer based on -myrcene useful in the field of tires (tyre sector). 5 According to a preferred aspect, the elastomeric homopolymer based on - myrcene useful in the tire industry is obtained through controlled radical polymerization of the ARGET-ATRP or ICAR- type ATRP. -Myrcene was selected as the starting molecule from 10 renewable and eco-sustainable sources and represents the monomeric constituent of the polymer. STATE OF THE ART The limited source of fossil fuels and their high environmental impact has determined an enormous interest in the identification of molecules derived from 15 from biological and renewable sources to replace petroleum derivatives. In In the field of polymers, research has been strongly focused in the identification of molecules obtainable from eco-sustainable sources for the development of monomers applicable in the synthesis of new polymers, including elastomers (Z. Wang, et al., Prog. Polym. Sci. (2020), 101, 101197). Products for applications in the tire sector from terpenes are already marketed by Kuraray Co. Ltd. as poly(-farnesene) (rubber liquid Farnesene, LFR) with Tg = -71°C (“Liquid Farnesene Rubber Used in 5 Car Tires for First Time,” can be found under https: / / www.kuraray.com / release / 2017 / 170220 (2017)). Sumimoto Rubber Industries has used this product as an additive to improve the Low-temperature performance of winter tires (P. Sarkar, AK Bhowmick, J. Appl. Polym. Sci. (2018), 135, 1–33). However, LFR is little 10 widespread in the global market since -farnesene is a very high monomer expensive. Note that its polymerizable group is chemically very similar to that of isoprene and butadiene normally used in tire production, as follows: A much more economically convenient monomer is -myrcene, also referred to as myrcene, obtained industrially by the pyrolysis of pinene (H. Zheng, et al., J. Anal. Appl. Pyrolysis (2017), 123, 99–106): -Myrcene has low toxicity and is polymerizable without further chemical modifications, similarly to -farnesene, sharing with it also the reactive unit of butadiene and isoprene. Furthermore, myrcene can be conveniently polymerized by various methods, including 5 radical polymerizations (free DL Trumbo, Polym. Bull. (1993), 31, 629–636 and RAFT N. Bauer, et al., ACS Sustain. Chem. Eng. (2017), 5, 10084–10092]), cationic polymerizations (MI Hulnik, et al. Polym. Chem. (2018), 9, 5690–5700), anionic (J. Glatzel, et al., Polym. Int. (2021), 70, 181–184), coordination (DH Lamparelli, et al., 10 Macromolecules (2020), 53, 1665–1673). Each polymerization method has advantages and disadvantages and provides polymers with different topologies, chain lengths and Regioselectivity. Possible regioselectivity is indicated in the following scheme 1. regiochemistry of beta-myrcene polymerization: Scheme 1 Poly(myrcene) (indicated by PMyr) due to its low Tg of approximately -70°C has properties similar to natural rubber (NR) (P. Sarkar, AK Bhowmick, 20 Ind. Eng. Chem. Res. (2018), 57, 5197–5206) and therefore can be considered a convenient substitute for it, as well as for polybutadiene (BR). Although the synthesis of -myrcene is already present in the literature, it is felt the need to find industrially applicable catalytic processes for the synthesis of a homopolymer of -myrcene with Tg comparable to that of 25 natural rubber to be usable in the tire industry so eco-sustainable, through green polymerization processes. DEFINITIONS Unless otherwise defined, all terms of art, notations and other terms scientific terms used here are intended to have the meanings commonly understood by those skilled in the art to which this description refers 5 belongs. In some cases, terms with commonly understood meanings are defined here for clarity and / or ready reference; the inclusion of such definitions in this description should therefore not be interpreted as representing a substantial difference from what is generally included in art. 10 The terms “comprising”, “having”, “including” and “containing” are to be be understood as open terms (i.e. the meaning “including, but not limited to”) and are to be considered as a support also for terms as “consisting essentially of”, “essentially consisting of”, “consist of” or “consisting of”. 15 For all ranges indicated in the text, figures and claims of the this patent application, it is intended that the extremes of these intervals they are included. The terms “obtainable”, “obtained”, “obtainable directly from”, “obtained directly from” are considered equivalent. 20 The acronym “LFR” stands for liquid farnesene rubber (from the English liquid farnesene rubber). The term -myrcene refers to the compound 7-methyl-3-methylene-1,6-octadiene. In this patent application, the terms -myrcene, beta-myrcene and myrcene are used as synonyms. 25 The acronym “Myr” refers to myrcene. The acronym “PMyr” or the acronym “pMyr” refers to poly(myrcene). The acronym “1,2 pMyr” stands for 1,2-poly(myrcene). The acronym “1,4 pMyr” stands for 1,4-poly(myrcene). The acronym “3,4 pMyr” stands for 3,4-poly(myrcene). 30 The acronym “NR” stands for natural rubber. The acronym “BR” stands for polybutadiene. The acronym “ATRP” refers to the procedure of polymerization called “Atom Transfer Radical Polymerization”, that is radical atom transfer polymerization. With the acronym “ARGET-ATRP” from the English “Activators ReGenerated by 5 Electron Transfer-ATRP” means the ATRP polymerization procedure, in which regenerated electron transfer activators are used and, in particular, in which the starting catalytic system is activated by the addition of a reducing agent. With the acronym “ICAR-ATRP” from the English “Initiators for Continuous 10 Activator Regeneration-ATRP”, refers to the polymerization procedure ATRP, in which peroxides are used as regenerated activators for electron transfer. The acronym “OTf” refers to the triflate substituent, synonymous with trifluoromethanesulfonate. 15 The acronym “DTBP” stands for the compound ditert-butyl peroxide. The acronym “AIBN” refers to the compound azobisisobutyronitrile. The acronym “BnCl” stands for benzyl chloride. BRIEF DESCRIPTION OF THE FIGURES 20 Figure 1 shows the H NMR spectrum (CDCl, 400 MHz, 25 °C), (ppm) of polymers obtained in examples 1-6, common to all said polymers. Figure 2 shows the thermogravimetric analysis (TGA) of the homopolymers synthesized in examples 1-6, common to all so-called homopolymers. 25 SUMMARY OF THE INVENTION The present invention relates to a process for the preparation of an elastomeric homopolymer based on -myrcene useful in the field of tires (tyre sector). The process of the invention exploits radical homopolymerization 30 controlled by the ARGET-ATRP or ICAR-ATRP type of -myrcene, allowing to obtain a homopolymer that has very low Tg, comparable to those of natural rubber. Controlled radical polymerization is a polymerization economical and green thanks to the low quantities of metal catalyst 5 used and the use of green solvents, such as anisole, toluene, 1,4-dioxane, 2-methyl tetrahydrofuran (2-MeTHF) or cyclopentadienyl methyl ether (CPME), preferably anisole. The object of the invention is also the homopolymer based on -myrcene obtained with the process of the invention. 10 Furthermore, the present invention has as its object the use of a homopolymer at -myrcene base obtained with the process of the invention for the preparing a tire. In particular, polymers obtained through radical polymerization controlled of the ARGET-ATRP or ICAR-ATRP type of -myrcene of the 15 present invention have Tg comparable to that of rubber natural and therefore are candidates to be eco-sustainable substitutes. Finally, the object of the invention is also a tire comprising a -myrcene-based homopolymer obtained with the process of the invention. 20 DETAILED DESCRIPTION OF THE INVENTION The object of the present invention is a process for the preparation of a elastomeric homopolymer based on -myrcene, wherein said homopolymer is obtained through controlled radical polymerization of the ARGET- type ATRP or ICAR-ATRP of -myrcene, useful in the tire industry (industry 25 tyre). In particular, the -myrcene-based homopolymer obtained with the process of the invention is used for the preparation of a tire suitable for the industrial sector, for the transport of goods and / or passengers, for agricultural and off-road applications. According to a preferred embodiment, the obtained -myrcene-based homopolymer 30 with the process of the invention is 1,4-poly(myrcene). According to a further preferred aspect, the 1,4-poly(myrcene) obtained with the process of the invention has the following formula (I): (THE) where n can vary between 10 and 2500, preferably between 10 and 350. 5 As indicated in the experimental part, the polymerization procedures led to the formation of 98% of 1,4-polymyrcene, the other structures they are in the minority and their single quantification cannot be carried out through common spectroscopic techniques due to their poor abundance. As previously reported in the literature, polymers 10 dienes and, therefore, also those of myrcene, which have a microstructure mainly 1,4- provide vulcanization products with better mechanical properties (elasticity, fatigue and fracture resistance) compared to those derived from polymers with 1,2- and 1,3-microstructure (Polymers 2022, 14, 1406; RCS Adv. 2019, 9, 3345). 15 The process of the invention is a controlled radical polymerization of the ARGET-ATRP or ICAR-ATRP type of -myrcene, preferably performed in the presence of at least one metal catalyst, at least one ligand, at least one catalyst activator and at least one catalyst initiator polymerization. 20 ARGET-ATRP uses regenerated electron transfer activators (K. Min, et al., Macromolecules (2007), 40, 1789–1791) and differs from the classic ATRP since the starting catalytic system features the metal in the highest and most stable oxidation state subsequently activated through the addition of a reducing agent. 25 In ICAR-ATRP polymerization, peroxides are used instead as regenerated electron transfer activators. ATRP (Atom Transfer Radical Polymerization) and all its variants involve the use of a metal catalyst with a binder. Both the ICAR and ARGET approaches make the reaction mixture less sensitive to atmospheric oxygen and this allows to reduce the concentration of the metal catalyst in the ppm range. Both Fully optimized processes allow the use of ppm quantities 5 of catalyst, halogenated initiator (cheap in most cases), inexpensive mono- or polydentate amine ligand and agent inexpensive reducing agent. Furthermore, the low amount of catalyst allows to avoid the purification of the polymeric product from the catalytic ash, and easier scale-up. 10 In the present invention the at least one metal catalyst is preferably chosen from Cu, Ti, Mo, Re, Fe, Ru, Os, Rh, Ni, Pd, and / or Co in all their oxidation states; preferably the metal catalyst is Cu in all its oxidation stages, and even more preferably the catalyst metallic is Cu(II) / Cu(I). 15 The at least one ligand for the metal catalyst of the polymerization of the present invention is a mono or polydentate binder, preferably a nitrogenous mono or polydentate binder. According to a preferred aspect, in radical polymerization techniques ATRP-ARGET and ATRP-ICAR controls of the present invention are 20 uses at least one binder chosen from: , , , , , , , , 1 2 3 4 5 6 where each R, R, R, R, R, R, or R is independently chosen from H, linear or branched alkyl, preferably C1-C12 alkyl, even more preferably n-nonenyl, substituted alkyl, preferably C1-C12 alkyl 5 substituted, preferably substituted with heteroatoms, NH, NO, OCH, phenyl, 2 2 3 substituted phenyl, preferably substituted with alkyl groups, even more preferably with C1-C12 alkyl groups, pyridyl or pyridyl substituted with alkyl groups, preferably C1-C12 alkyl groups. At least one binder selected from the following is particularly preferred: 10 , 1 2 3 where each R, R, R is independently chosen from H, n-nonenyl, NH, NO2, OCH3. At least one polymerization initiator is also present, preferably halogenated and even more preferably chosen from: 15 , , , , , , , , , , , in which: - X is halogen (Cl, Br, I); - each R is chosen independently from H, linear or branched alkyl, preferably C -C alkyl, even more preferably ethyl, alkyl 1 12 5 substituted, preferably C1-C12 substituted alkyl, more preferably substituted with heteroatoms, phenyl, substituted phenyl, preferably substituted with alkyl groups, even more preferably substituted with alkyl groups C1-C12, heterocycle, preferably a cyclic ester, substituted heterocycle, preferably with a halogen or with OTf. 10 At least one selected polymerization initiator is particularly preferred Between: , in which: - X is Cl or Br; 15 - R is ethyl. Even more preferably, the polymerization initiator is benzyl chloride. When the ARGET-ATRP technique is used in the present invention, the at least one catalyst activator is a selected reducing agent preferably between tin 2-ethylhexanoate (Sn(EH)), glucose, beta- 20 cyclodextrins, ascorbic acid, hydrazine, phenylhydrazine, phenols, amines aliphatic, metallic silver, metallic copper and other zero-valent metals. According to a particularly preferred aspect, the reducing agent is tin 2-ethylhexanoate. When the ICAR-ATRP technique is used in the present invention, 25 the at least one catalyst activator is a peroxide and / or a diazo compound chosen from: , , , where each R is independently chosen from H, linear alkyl or branched, preferably C -C alkyl, even more preferably it is tert- 1 12 butyl, substituted alkyl, preferably substituted C1-C12 alkyl, 5 preferably substituted with at least one heteroatom, phenyl and / or group cyano, phenyl, substituted phenyl, preferably substituted with alkyl groups, even more preferably substituted with C1-C12 alkyl groups, heterocycle, preferably a cyclic ester, substituted heterocycle, preferably with a halogen or with OTf. 10 According to a preferred aspect, the peroxide is preferably selected from ditertbutylperoxide, tertbutyl hydroperoxide, cumyl peroxide, cumyl hydroperoxide, benzoyl peroxide, diisobutyryl peroxide, isobutyryl hydroperoxide and / or diazo compounds, preferably AIBN. According to a more preferred aspect, peroxide is 15 ditert-butyl peroxide. According to a further preferred aspect, the polymerization reactions controlled radical of the ARGET-ATRP or ICAR-ATRP type used in The present invention is performed in a green solvent, such as for example anisole, toluene, 1,4-dioxane, 2-methyl tetrahydrofuran (2-MeTHF) or 20 cyclopentadienyl methyl ether (CPME), preferably anisole. The chemical composition and molar mass of the homopolymer obtained with the process of invention are controlled through parameters of the synthesis process, and with them the transition temperature is controlled vitreous (Tg) of the final material. 25 The glass transition temperature (Tg) of the -myrcene homopolymer obtained with the process of the present invention is between -90° C and -40° C, preferably between -80° C and -50° C. The molecular mass of the homopolymer is influenced by the amount of monomer in the feed mixture, from the temperature and times of polymerization as well as the catalytic system used. The physical state of the homopolymer varies from that of a highly concentrated liquid 5 viscous to that of a waxy solid, depending on its mass molecular. The object of the invention is therefore also the homopolymer based on -myrcene obtained with the process of the invention as described above. According to a preferred embodiment, the obtained -myrcene-based homopolymer 10 with the process of the invention is 1,4-poly(myrcene). According to a further preferred aspect, the 1,4-poly(myrcene) obtained with the process of the invention has the following formula (I): (THE) Where n can range between 10 and 2500, preferably between 10 and 350. 15 Furthermore, the present invention also has as its object the use of a homopolymer based on -myrcene obtained with the process of the invention for preparing a tire. According to a favorite aspect, a tire for is of particular interest the industrial sector, for the transport of goods and / or passengers, for the 20 applications for agriculture and / or off-road. Advantageously, the homopolymer of -myrcene obtained as above described has Tg comparable to that of natural rubber and therefore it is a candidate to be an eco-sustainable replacement. In fact, polymyrcene can be considered an alternative to polybutadiene, 25 as the chemical structure appears to be very similar, as very similar they are the properties. Examples of Tg of polybutadienes are given in Table 1 below. commercial used in the tire world. Table 1 Composition (mol%) cis-1,4 vinyl (on BD)% Mooney Tg Sample (*) (mol%) (mol%) (%) (°C) BUNA CB 22 96 0.6 63 -106 Nipol BR 1261 43.2 8.8 54 -94 BR 500 42.2 15.1 61 -88 Europrene BR HV80 49 77 70 -31 cis-1,2 Crystallinity Mooney Tg (mol%) (%) (%) (°C) RB840 94 36 83 -30 (*) BUNA CB 22 supplied by Lanxess; Nipol BR 1261 supplied by Zeon; BR 500 and RB840 supplied by Eneos; Europrene BR HV80 supplied by Versalis. The object of the invention is therefore also a tyre comprising a 5 -myrcene homopolymer obtained with the process of the invention above described, preferably a 1,4-type -myrcene homopolymer poly(myrcene), more preferably a 1,4-type -myrcene homopolymer poly(myrcene) of formula (I): (THE) 10 where n can range between 10 and 2500, preferably between 10 and 350. The invention will now be illustrated by some examples whose purpose is not absolutely to be understood as limiting the scope of protection. EXAMPLES 15 1. Materials and methods 1.1 Materials CuBr2, CuCl2, tin diethylhexanoate (Sn(EH)2), N,N,N',N'',N''-pentamethyl diethylenetriamine (PMDETA), bipyridine (BiPy), 1,1,4,7,10,10- hexamethyltriethylenetriamine (HMTETA), 4,4'-dimethoxy-2,2'-bipyridine (DMeO- BiPy), benzyl bromide (BnBr), ethyl 2-bromoisobutyrate (EBiB), benzyl chloride (BnCl), ditert-butylperoxide (DTBP), methanol, sulfuric acid 98%, n- Hexane is used as received from TCI. Anisole is anhydrified 5 for at least 24 h on CaCl2. Myrcene (Myr) is purified on a column of basic alumina before use in polymerization. 2. Synthesis of myrcene (Myr) homopolymers by polymerization controlled radical 10 2.1 General procedure for the polymerization of Myr by ARGET- ATRP In a 50 mL tailed flask equipped with a magnetic stirrer, are placed, in a nitrogen atmosphere, anisole, CuCl2 and ligand. The reaction mixture is shaken until it turns green. Then 15 myrcene, the polymerization initiator, and tin are added ethylhexanoate (Sn(EH)2). The flask is thermostated at the temperature desired and kept under magnetic stirring for the established time. term, the contents of the flask are poured into acidified methanol with two drops of 98% sulfuric acid (60 mL), the precipitated polymer is 20 recovered by filtration, washed with methanol (2 x 10 mL) and dried in a vacuum oven at 80°C. A white gum is obtained. The polymer yield is calculated using the equation: g (Myr) / g (PMyr) * 100 25 Example 1 According to the general procedure, in a 50 mL tailed flask, equipped with magnetic stirrer, 2.8 mL of anisole are placed in a nitrogen atmosphere, 109 L CuCl2 (0.4 M solution in DMF, 0.0436 mmol), 109 L BiPy (0.4 M solution in DMF, 0.0436 mmol). The reaction mixture is 30 shaken for 5 minutes until it turns green. Subsequently 3 mL of Myr (2.38 g, 17.5 mmol), 50 L of BnCl (0.436 mmol) and 29 L of Sn(EH) (0.0872 mmol) are added. The flask is thermostated at 130°C and kept under magnetic stirring for the time established. At the end, the contents of the flask are poured into 60 mL of methanol acidified with two drops of 98% sulfuric acid, the polymer 5 precipitate is recovered by filtration, washed with 10 mL of methanol twice, and dried in a vacuum oven at 80 °C. A White rubber. The polymer yield is calculated using the equation: g (Myr) / g (PMyr) * 100 Yield = 10 wt%; Mn = 50.7 kDa; Ð = 1.18. Tg = -60 °C 10 H NMR: ca 98% 1.4 pMyr Example 2 According to the general procedure, in a 50 mL tailed flask, equipped with magnetic stirrer, 2.8 mL of anisole are placed in a nitrogen atmosphere, 15 109 L of CuCl2 (0.4 M solution in DMF, 0.0436 mmol), 109 L of DMeO- BiPy (0.4 M solution in DMF, 0.0436 mmol). The reaction mixture is shake for 5 minutes until it turns green. Subsequently 3 mL of Myr (2.38 g, 17.5 mmol), 50 L of BnCl (0.436 mmol) and 29 L of Sn(EH)2 (0.0872 mmol) are added. The flask is 20 thermostated at 130 °C and kept under magnetic stirring for the time established. At the end, the contents of the flask are poured into 60 mL of methanol acidified with two drops of 98% sulfuric acid, the polymer precipitate is recovered by filtration, washed with 10 mL of methanol twice, and dried in a vacuum oven at 80 °C. A 25 white rubber. The polymer yield is calculated using the equation: g (Myr) / g (PMyr) * 100 Yield = 30 wt% (690 mg). M 6.02 kDa; Ð = 2.08. T = -58 °C ng H NMR: ca 98% 1.4 pMyr 30 Example 3 According to the general procedure, in a 50 mL tailed flask, equipped with magnetic stirrer, 2.8 mL of anisole are placed in a nitrogen atmosphere, 109 L CuBr2 (0.4 M solution in DMF, 0.0436 mmol), 109 L BiPy (0.4 M solution in DMF, 0.0436 mmol). The reaction mixture is 5 shake for 5 minutes until it turns green. Subsequently 3 mL of Myr (2.38 g, 17.5 mmol), 50 L of BnCl (0.436 mmol) and 29 L of Sn(EH) (0.0872 mmol) are added. The flask is thermostated at 130°C and kept under magnetic stirring for the time established. At the end, the contents of the flask are poured into 60 mL of 10 methanol acidified with two drops of 98% sulfuric acid, the polymer precipitate is recovered by filtration, washed with 10 mL of methanol twice, and dried in a vacuum oven at 80 °C. A White rubber. The polymer yield is calculated using the equation: g (Myr) / g (PMyr) * 100 15 Yield 57 wt%. Mn 7.9 kDa; Ð 1.59. Tg < -80 °C (not determinable with accuracy due to the limitations of the instrument used). H NMR: ca 98% 1.4 pMyr 2.2 General procedure for the polymerization of myrcene by ICAR- 20 ATRP In a 50 mL tailed flask equipped with a magnetic stirrer, are placed, in a nitrogen atmosphere, anisole, CuCl2 and ligand. The reaction mixture is shaken until it turns green. Then myrcene, the polymerization initiator, and DTBP are added. The flask 25 is thermostated at the desired temperature and kept under stirring magnetic for the set time. At the end, the contents of the flask are poured into methanol acidified with two drops of 98% sulfuric acid (60 mL), the precipitated polymer is recovered by filtration, washed with methanol (2 x 10 mL) and dried in a vacuum oven at 80°C. A 30 white rubber. The polymer yield is calculated using the equation: g (Myr) / g (PMyr) * 100 Example 4 According to the general procedure, in a 50 mL tailed flask, equipped with 5 magnetic stirrer, 3 mL of anisole are placed in a nitrogen atmosphere, 11 L CuCl2 (0.4 M solution in DMF, 0.00436 mmol), 5 mg DMeO- BiPy (0.0236 mmol). The reaction mixture is stirred for 5 minutes until upon reaching a green color. Subsequently 3 mL of Myr (2.38 g, 17.5 mmol), 1.5 L of BnCl (0.013 mmol), and 32 L of DTBP (0.1744 10 mmol) are added. The flask is thermostated at 110°C and kept under magnetic stirring for the established time. At the end, the contents of the The flask is poured into 60 mL of acidified methanol with two drops of sulfuric acid 98%, the precipitated polymer is recovered by filtration, washed with 10 mL of methanol twice, and dried in an oven 15 vacuum at 80°C. A white rubber is obtained. The polymer yield is calculated through the equation: g (Myr) / g (PMyr) * 100. Yield = 30 wt% (720 mg). Mn = 19.9 kDa; Ð =1.59. Tg = - 72 °C. H NMR: ca 98% 1.4 pMyr Example 5 According to the general procedure, in a 50 mL tailed flask, equipped with magnetic stirrer, 3 mL of anisole are placed in a nitrogen atmosphere, 11 L CuCl (0.4 M solution in DMF, 0.00436 mmol), 5 mg BiPy 25 (0.0236 mmol). The reaction mixture is stirred for 5 minutes until reaching a green color. Subsequently 3 mL of Myr (2.38 g, 17.5 mmol), 1.5 L of BnCl (0.013 mmol), and 32 L of DTBP (0.1744 mmol) are added. The flask is thermostated at 110°C and kept under magnetic stirring for the established time. At the end, the contents of the 30 flask is poured into 60 mL of acidified methanol with two drops of sulfuric acid 98%, the precipitated polymer is recovered by filtration, washed with 10 mL of methanol twice, and dried in an oven vacuum at 80°C. A white rubber is obtained. The polymer yield is calculated through the equation: g (Myr) / g (PMyr) * 100. 5 Yield = 25 wt% (600 mg). Mn = 7.3 kDa; Ð = 2.16. Tg = - 72 °C. H NMR: ca 98% 1.4 pMyr Example 6 According to the general procedure, in a 50 mL tailed flask, equipped with 10 magnetic stirrer, 3 mL of anisole are placed in a nitrogen atmosphere, 11 L CuCl (0.4 M solution in DMF, 0.00436 mmol), 5 mg DMeO- BiPy A(0.0236 mmol). The reaction mixture is stirred for 5 minutes until upon reaching a green color. Subsequently 3 mL of Myr (2.38 g, 17.5 mmol), 1.5 L of Ebib (0.013 mmol), and 32 L of DTBP (0.1744 15 mmol) are added. The flask is thermostated at 110°C and kept under magnetic stirring for the established time. At the end, the contents of the The flask is poured into 60 mL of acidified methanol with two drops of sulfuric acid 98%, the precipitated polymer is recovered by filtration, washed with 10 mL of methanol twice, and dried in an oven 20 vacuum at 80°C. A white rubber is obtained. The polymer yield is calculated through the equation: g (Myr) / g (PMyr) * 100. Yield = 6 wt% (140 mg). Mn = 2.03; Ð =1.41. Tg = -69 °C. H NMR: ca 98% 1.4 pMyr Comments The parameters of myrcene polymers are shown in Table 2 below. obtained through controlled radical polymerization. 30 Table 2. Parameters of myrcene polymers obtained by controlled radical polymerization. Type CuX Time Index of polymeriz Le- Initia- di Resa M Polidi- T ng -ization ganter reac- (%) (kDa) spersivity (°C) ne (h) Ð Ex. 1 CuCl2 BiPy 10 50.7 1.18 -60 BnCl ARGET- DMeO Ex. 2 CuCl 30 6.02 2.08 -58 ATRP -BiPy Ex. 3 CuBr2 BiPy 57 7.9 1.59 <-80 DMeO 70 Ex. 4 BnCl 30 19.9 1.59 -72 -BiPy ICAR- Ex. 5 CuCl2 BiPy BnCl 25 7.3 2.16 -72 ATRP DMeO Ex. 6 EbiB 6 2.03 1.41 -69 -BiPy 3. Characterization of the obtained polymers The polymers obtained in examples 1-6 are characterized by the following values ​​of 5 H NMR spectrum (CDCl, 400 MHz, 25 °C), (ppm): 5.12 (2H, C=CH), 2.03 (8H, CH2), 1.67 (3H, CH3), 1.59 (3H, CH3), common to all said polymers, reported in figure 1. Figure 2 shows the thermogravimetric analysis (TGA) of the polymers. 10 synthesized reported in examples 1-6, common to all said polymers. THE AGENCY Dr. Cristina Biggi

Claims

1. Process for the preparation of a homopolymer based on β-myrcene, wherein said homopolymer is obtained by controlled radical polymerization of the ARGET-ATRP or ICAR-ATRP type of β-myrcene.

2. Process according to claim 1, wherein the controlled radical polymerization of the ARGET-ATRP or ICAR-ATRP type of β-myrcene occurs in the presence of at least one metal catalyst, at least one ligand, at least one catalyst activator and at least one polymerization initiator.

3. A process according to any of the preceding claims, wherein the at least one metal catalyst is selected from Cu, Ti, Mo, Re, Fe, Ru, Os, Rh, Ni, Pd, and / or Co in all their oxidation states, preferably the at least one metal catalyst being Cu in all its oxidation states, and even more preferably the at least one metal catalyst being Cu(ll) / Cu(l).

4. Process according to any of the preceding claims, wherein the at least one binder is a mono- or polydentate binder, preferably a nitrogenous mono- or polydentate binder and even more is selected from: KNR! v...- NNR R3 pp R?R r rr R'5 1 R4. , SIJ rA........ZN'R4 D.ssa Cristina Biggi (Registered Register No. 1239 B) 21 .P0380.12.IT.5 R1 ,_______ N-R2 R4>N i \ N · ....R3 where each R, R1, R2, R3, R4, R5 or R6 is independently selected from Η, linear or branched alkyl, preferably C1-C12 alkyl, even more preferably n-nonenyl, substituted alkyl, preferably C1-C12 alkyl 5 substituted, preferably substituted with heteroatoms, NH2, NO2, OCH3, phenyl, substituted phenyl, preferably substituted with alkyl groups, even more preferably with C1-C12 alkyl groups, pyridyl or pyridyl substituted with alkyl groups, preferably C1-C12 alkyl groups. 10 5. Process according to claim 4, wherein the at least one ligand is selected from: wherein each R1, R2, R3 is independently selected from H, n-nonenyl, NH2, NO2, OCH3.

6. Process according to any of the preceding claims, wherein the at least one polymerization initiator is a halogenated initiator, preferably selected from: D.ssa Cristina Biggi (Registered Register No. 1239 B) 21 .P0380.12.IT.5 X ' X'Xr rrr rr Q-'XI '--aARX ' ·:α r wherein: - X is halogen (Cl, Br, I); - each R is independently selected from H, linear or branched alkyl, preferably C1-C12 alkyl, even more preferably ethyl, substituted alkyl, preferably substituted C1-C12 alkyl, more preferably substituted with heteroatoms, phenyl, substituted phenyl, preferably substituted with alkyl groups, even more preferably substituted with C1-C12 alkyl groups, heterocycle, preferably a cyclic ester, substituted heterocycle, preferably with a halogen or with OTf.

7. Process according to claim 6, wherein the at least one polymerization initiator is selected from: x ' r wherein: - X is Cl or Br; - R is ethyl.

8. Process according to any of the preceding claims, wherein when the controlled radical polymerization reaction is of the ARGET-ATRP type, the at least one catalyst activator is a reducing agent preferably selected from tin 2-ethylhexanoate (Sn(EH)2), glucose, beta-cyclodextrins, ascorbic acid, hydrazine, phenyl-hydrazine, phenols, aliphatic amines, metallic silver, metallic copper and other zerovalent metals, more preferably it is tin 2-ethylhexanoate.

9. Process according to any of claims 1 to 7, wherein when the controlled radical polymerization reaction is of the ICAR-ATRP type, the at least one catalyst activator is a peroxide and / or a diazo compound.

10. Process according to claim 9, wherein the at least one catalyst activator is a peroxide and / or a diazo compound selected from: O ro°'r %'<* NN jjj wherein each R is independently selected from H, linear or branched alkyl, preferably C1-C12 alkyl, even more preferably tert-butyl, substituted alkyl, preferably substituted C1-C12 alkyl, preferably substituted with at least one heteroatom, phenyl and / or cyano group, phenyl, substituted phenyl, preferably substituted with alkyl groups, even more preferably substituted with C1-C12 alkyl groups, heterocycle, preferably a cyclic ester, substituted heterocycle, preferably with a halogen or with OTf.

11. A process according to claim 10, wherein the at least one catalyst activator is a peroxide and / or a diazo compound selected from ditert-butylperoxide, tert-butyl hydroperoxide, cumyl peroxide, cumyl hydroperoxide, benzoyl peroxide, diisobutyryl peroxide, isobutyryl hydroperoxide and / or diazo compounds, preferably AIBN, more preferably it is ditert-butylperoxide. 21 .P0380.12.IT.5 Dr. Cristina Biggi (Registered Register No. 1239 B) 12. Homopolymer based on β-myrcene obtained according to any of claims 1 to 11.

13. A β-myrcene homopolymer according to claim 12, wherein the β-myrcene homopolymer is of the 1,4-poly(myrcene) type.

14. A β-myrcene homopolymer according to claim 13, wherein the β-myrcene-based homopolymer has the following formula (I): ' \— / 4i / (I) wherein n can vary between 10 and 2500, preferably between 10 and 350.

15. A β-myrcene homopolymer according to any of claims 12 to 14, wherein the glass transition temperature (Tg) is between -90° C and -40° C, preferably between -80° C and -50° C.

16. Use of a β-myrcene-based homopolymer according to any of claims 12 to 15, for the preparation of a tire, preferably suitable for the industrial sector, for the transport of goods and / or passengers, for agricultural and / or off-road applications.

17. A tire comprising a β-myrcene-based homopolymer according to any of claims 12 to 15, preferably a β-myrcene homopolymer of formula (I): ' \— / 4i / (I) wherein n can vary between 10 and 2500, preferably between 10 and 350.