GRAFTED POLYMER CARRYING PENDENT IMIDAZOLE FUNCTIONAL GROUPS
20220235164 · 2022-07-28
Inventors
Cpc classification
C08F279/04
CHEMISTRY; METALLURGY
C07D233/61
CHEMISTRY; METALLURGY
C07D233/60
CHEMISTRY; METALLURGY
C07D405/06
CHEMISTRY; METALLURGY
International classification
Abstract
A modified polymer is obtained by grafting of at least one compound of formula (I) onto at least one unsaturation of the initial polymer chain
##STR00001##
in which Q represents a dipole comprising at least one nitrogen atom; A represents a divalent heteroaromatic ring optionally substituted with one or more identical or different linear or branched aliphatic hydrocarbon-based chains, optionally substituted or interrupted with one or more heteroatoms; E represents a divalent hydrocarbon-based group which may optionally contain one or more heteroatoms; R.sub.1 represents a hydrogen atom or a C.sub.1-C.sub.20 alkyl group; and Y and Z, which may be identical or different, each represent a hydrogen atom or a hydrocarbon-based chain, Y and Z together also possibly forming a ring, notably an aromatic ring, with the carbon atoms of the imidazole ring to which they are attached.
Claims
1.-15. (canceled)
16. A modified polymer obtained by grafting of at least one compound of formula (I) onto at least one unsaturation of an initial polymer chain ##STR00034## in which: Q represents a dipole comprising at least one nitrogen atom; A represents a divalent heteroaromatic ring optionally substituted with one or more identical or different linear or branched aliphatic hydrocarbon-based chains, optionally substituted or interrupted with one or more heteroatoms; E represents a divalent hydrocarbon-based group which may optionally contain one or more heteroatoms; R.sub.1 represents a hydrogen atom or a C.sub.1-C.sub.20 alkyl group; and Y and Z, which may be identical or different, each represent a hydrogen atom or a hydrocarbon-based chain, Y and Z together also possibly forming a ring with the carbon atoms of the imidazole ring to which they are attached.
17. The modified polymer according to claim 16, wherein a molar degree of grafting of the compound of formula (I) is in a range extending from 0.01% to 15%.
18. The modified polymer according to claim 16, wherein Q is a group of formula (II), (III) or (IV) ##STR00035## in which: the symbol * represents the attachment of Q to A; R.sub.2 and R.sub.4 are selected, independently of each other, from a hydrogen atom, a linear or branched C.sub.1-C.sub.20 alkyl, a C.sub.3-C.sub.20 cycloalkyl optionally substituted with one or more aliphatic hydrocarbon-based chains, which are preferably saturated, linear or branched, and a C.sub.6-C.sub.20 aryl optionally substituted with one or more aliphatic hydrocarbon-based chains; and R.sub.3 is selected from the group consisting of linear or branched C.sub.1-C.sub.20 alkyls, C.sub.3-C.sub.20 cycloalkyls optionally substituted with one or more aliphatic hydrocarbon-based chains, and C.sub.6-C.sub.20 aryls optionally substituted with one or more aliphatic hydrocarbon-based chains.
19. The modified polymer according to claim 18, wherein the compound of formula (I) is chosen from the compounds of formula (IIa) ##STR00036## in which: A represents a divalent heteroaromatic ring optionally substituted with one or more identical or different linear or branched aliphatic hydrocarbon-based chains, optionally substituted or interrupted with one or more heteroatoms; E represents a divalent hydrocarbon-based group which may optionally contain one or more heteroatoms; R.sub.1 represents a hydrogen atom or a C.sub.1-C.sub.20 alkyl group; Y and Z, which may be identical or different, each represent a hydrogen atom or a hydrocarbon-based chain, Y and Z together also possibly forming a ring with the carbon atoms of the imidazole ring to which they are attached; R.sub.2 is selected from a hydrogen atom, a linear or branched C.sub.1-C.sub.20 alkyl, a C.sub.3-C.sub.20 cycloalkyl optionally substituted with one or more aliphatic hydrocarbon-based chains, and a C.sub.6-C.sub.20 aryl optionally substituted with one or more aliphatic hydrocarbon-based chains; and R.sub.3 is selected from the group consisting of linear or branched C.sub.1-C.sub.20 alkyls, C.sub.3-C.sub.20 cycloalkyls optionally substituted with one or more aliphatic hydrocarbon-based chains, and C.sub.6-C.sub.20 aryls optionally substituted with one or more aliphatic hydrocarbon-based chains.
20. The modified polymer according to claim 16, wherein A is a divalent heteroaromatic ring formed from 5 to 10 atoms, optionally substituted with one or more identical or different linear or branched, aliphatic C.sub.1-C.sub.24 hydrocarbon-based chains, optionally substituted or interrupted with one or more heteroatoms.
21. The modified polymer according to claim 19, wherein the compound of formula (IIa) is selected from compounds of formula (IIb) ##STR00037## in which: X represents a heteroatom selected from a sulfur atom, an oxygen atom and a nitrogen atom; E represents a divalent hydrocarbon-based group which may optionally contain one or more heteroatoms; R.sub.1 represents a hydrogen atom or a C.sub.1-C.sub.20 alkyl group; Y and Z, which may be identical or different, each represent a hydrogen atom or a hydrocarbon-based chain, Y and Z together also possibly forming a ring with the carbon atoms of the imidazole ring to which they are attached; R.sub.2 is selected from a hydrogen atom, a linear or branched C.sub.1-C.sub.20 alkyl, a C.sub.3-C.sub.20 cycloalkyl optionally substituted with one or more aliphatic hydrocarbon-based chains, and a C.sub.6-C.sub.20 aryl optionally substituted with one or more aliphatic hydrocarbon-based chains; and R.sub.3 is selected from the group consisting of linear or branched C.sub.1-C.sub.20 alkyls, C.sub.3-C.sub.20 cycloalkyls optionally substituted with one or more aliphatic hydrocarbon-based chains, and C.sub.6-C.sub.20 aryls optionally substituted with one or more aliphatic hydrocarbon-based chains.
22. The modified polymer according to claim 18, wherein R.sub.2 is a hydrogen atom and R.sub.3 is selected from C.sub.1-C.sub.20 alkyls and C.sub.6-C.sub.20 aryls.
23. The modified polymer according to claim 16, wherein E is selected from linear or branched, saturated aliphatic C.sub.1-C.sub.24, optionally interrupted with one or more nitrogen, sulfur or oxygen atoms.
24. The modified polymer according to claim 16, wherein E is selected from the groups —R—, —NHR—, —OR— and —SR—, where R is a linear or branched C.sub.1-C.sub.24 alkylene.
25. The modified polymer according to claim 16, wherein Y and Z, which may be identical or different, each represent a hydrogen atom or a linear or branched C.sub.1-C.sub.24 alkyl, Y and Z together also possibly forming a ring with the carbon atoms of the imidazole ring to which they are attached.
26. The modified polymer according to claim 16, wherein Y and Z are a hydrogen atom.
27. The modified polymer according to claim 16, wherein R.sub.1 is a hydrogen atom or a C.sub.1-C.sub.6 alkyl.
28. The modified polymer according to claim 16, wherein the compound of formula (I) is the compound of formula ##STR00038##
29. The modified polymer according to claim 16, wherein the initial polymer is an elastomer.
30. A composition comprising at least one modified polymer according to claim 16 and at least one additive.
Description
V—EXAMPLES
[0210] The examples which follow make it possible to illustrate the invention; however, the invention shall not be limited to these examples alone.
[0211] 5.1 Characterizations of the Molecules
[0212] The structural analysis and the determination of the molar purities of the molecules synthesized are performed by NMR analysis. The spectra are acquired on a Brüker Avance 3 400 MHz spectrometer equipped with a “5 mm BBFO Z-grad broad band” probe. The quantitative .sup.1H NMR experiment uses a simple 30° pulse sequence and a repetition delay of 3 seconds between each of the 64 acquisitions. The samples are dissolved in a deuterated solvent, deuterated dimethyl sulfoxide (DMSO), unless otherwise indicated. The deuterated solvent is also used for the “lock” signal. For example, calibration is performed on the signal of the protons of the deuterated DMSO at 2.44 ppm relative to a TMS reference at 0 ppm. The .sup.1H NMR spectrum coupled with the 2D .sup.1H/.sup.13C HSQC and .sup.1H/.sup.13C HMBC experiments enable the structural determination of the molecules (cf. assignment tables). The molar quantifications are performed from the quantitative 1D .sup.1H NMR spectrum.
[0213] 5.2 Characterization of the Molecules Grafted onto a Diene Elastomer
[0214] The determination of the molar content of the grafted compound tested on a diene elastomer is performed by NMR analysis. The spectra are acquired on a Brüker 500 MHz spectrometer equipped with a “5 mm BBFO Z-grad CryoProbe” probe. The quantitative .sup.1H NMR experiment uses a simple 30° pulse sequence and a repetition delay of 5 seconds between each acquisition. The samples are dissolved in a deuterated solvent, deuterated chloroform (CDCl.sub.3) unless indicated otherwise, for the purpose of obtaining a “lock” signal. 2D NMR experiments made it possible to confirm the nature of the grafted unit by means of the chemical shifts of the carbon atoms and protons.
[0215] 5.3 Measurement of the Number-Average (Mn) and Weight-Average (Mw) Molar Masses and of the Polydispersity Index of the Diene Elastomers.
[0216] Unless expressly indicated otherwise, the number-average and weight-average molar masses of the diene elastomers used are measured by the size exclusion chromatography (SEC) technique. SEC makes it possible to separate macromolecules in solution according to their size through columns filled with a porous gel. The macromolecules are separated according to their hydrodynamic volume, the bulkiest being eluted first.
[0217] Without being an absolute method, SEC makes it possible to comprehend the molar mass distribution of an elastomer. The various number-average molar masses (Mn) and weight-average molar masses (Mw) may be determined from commercial standards and the polydispersity index (PI=Mw/Mn) may be calculated via a “Moore” calibration.
[0218] There is no specific treatment for the elastomer sample before analysis. Said sample is simply dissolved to a concentration of about 1 g/l, in chloroform or in the following mixture: tetrahydrofuran+1 vol % of diisopropylamine+1 vol % of triethylamine+1 vol % of distilled water (vol % =% by volume). The solution is then filtered through a filter with a porosity of 0.45 μm before injection.
[0219] The apparatus used is a Waters Alliance chromatograph. The elution solvent is the following mixture: tetrahydrofuran+1 vol % of diisopropylamine+1 vol % of triethylamine or chloroform according to the solvent used for dissolving the elastomer. The flow rate is 0.7 ml/min, the temperature of the system is 35° C. and the analysis time is 90 min. A set of four Waters columns in series, having the commercial names Styragel HMW7, Styragel HMW6E and two Styragel HT6E, is used.
[0220] The volume of the solution of the elastomer sample injected is 100 The detector is a Waters 2410 differential refractometer at a wavelength of 810 nm. The software for processing the chromatographic data is the Waters Empower system.
[0221] The calculated average molar masses are relative to a calibration curve produced from PSS Ready Cal-Kit commercial polystyrene standards.
[0222] 5.4 Synthesis of 1-(5-((2-Methyl-1H-Imidazol-1-Yl)Methylfuran-2-Yl)-N-Phenylmethanimine Oxide (Compound E)
[0223] 1-(5-((2-Methyl-1H-imidazol-1-yl)methylfuran-2-yl)-N-phenylmethanimine oxide may be synthesized according to the following reaction scheme
##STR00020##
[0224] 1-(5-((2-Methyl-1H-imidazol-1-yl)methylfuran-2-yl)-N-phenylmethanimine oxide is synthesized in two steps which are described below. All the chemical compounds used during this synthesis are obtained from “Sigma-Aldrich” or from “Fischer Scientific”.
[0225] 5-(Hydroxymethyl)furan-2-carbaldehyde (compound A, CAS 67-47-0) is commercial or may be synthesized biochemically or chemically from fructose.
[0226] The product N-phenylhydroxylamine (compound D, CAS 100-65-2) is commercial or may be synthesized from nitrobenzene according to the procedure described in Organic Syntheses, Coll. Vol. 1, page 445 (1941); Vol. 4, page 57 (1925).
[0227] 5-(Chloromethyl)furan-2-carbaldehyde (compound B) may be synthesized from fructose or from 5-(hydroxymethyl)furan-2-carbaldehyde according to the procedure described in Sanda, Komla et al., Synthesis of 5-(bromomethyl)- and of 5-(chloromethyl)-2-furancarboxaldehyde, Carbohydrate Research, 187(1), 15-23; 1989
5.4.1 Step 1: Synthesis of 5-((2-Methyl-1H-Imidazol-1-Yl)Methyl)Furan-2-Carbaldehyde (Product C)
[0228] A mixture of 2-methylimidazole (4.83 g; 58.80 mmol; 2.5 eq.) and 5-(chloromethyl)furan-2-carbaldehyde (3.40 g; 23.52 mmol) in DMF (4 ml) is heated to a bath temperature of 70° C. After stirring for 2-3 hours at this temperature and 2 hours at a bath temperature of 80° C., the reaction medium is diluted with water (50 ml) and the organic phase is then separated out. The aqueous phase is extracted four times with dichloromethane (four times 20 ml). The organic phase fractions are combined and then washed with water (four times 5 ml) and then concentrated under reduced pressure (2-3 mbar; 32° C.) to give a black-coloured oil (2.44 g; 12.8 mmol) in a yield of 55%. This product is engaged in the following step without further purification.
5.4.2 Step 2: Synthesis of 1-(5-((2-Methyl-1H-Imidazol-1-Yl)Methyl)Furan-2-Yl)-N-Phenylmethanimine Oxide (Product E)
[0229] To a solution of 5-((2-methyl-1H-imidazol-1-yl)methyl)furan-2-carbaldehyde (compound C) (5.00 g; 26.3 mmol) in ethanol (5 ml) at a bath temperature of 35-40° C. is added N-phenylhydroxylamine (2.87 g; 26.3 mmol; 1 eq.) portionwise over 5 minutes. The reaction medium is heated up to a bath temperature of 60° C. After stirring for 1.5 hours at this temperature and then returning to a temperature of 30-35° C., tert-butyl methyl ether (15 ml) is added dropwise. After stirring for one hour at room temperature (23° C.), the precipitate obtained is filtered off and washed on the filter with a mixture of ethanol and tert-butyl methyl ether (1 ml and 5 ml) and then with tert-butyl methyl ether (8 ml). A light-brown solid with a melting point of 147-150° C. is obtained in a yield of 68.4% (5.06 g; 17.99 mmol) and a molar purity of greater than 98% (.sup.1H NMR).
##STR00021##
TABLE-US-00001 TABLE 1 No. δ .sup.1H (ppm) δ .sup.13C (ppm) 1 2.37 12.6 2 / 144.2 3 6.87 127.1 4 6.81 119.0 5 4.99 42.6 6 / 150.7 7 6.39 110.8 8 7.87 116.4 9 / 147.5 10 8.01 123.1 11 / 146.7 12 7.71 120.5 13 7.41 128.7 14 7.40 129.6
5.5 Grafting of Polymer with Compound E
5.5.1 Manufacture of a Styrene-Butadiene Copolymer Grafted with 1-(5-((2-Methyl-1H-Imidazol-1-yl)Methyl)Furan-2-Yl)-N-Phenylmethanimine Oxide (Compound E)
[0230] 1-(5-((2-Methyl-1H-imidazol-1-yl)methyl)furan-2-yl)-N-phenylmethanimine oxide (0.31; 1.14 mmol) is incorporated into 15 g of a styrene-butadiene copolymer SBR (containing 26.5% by weight of styrene relative to the total weight of the copolymer and 24% by weight of 1,2-butadiene units relative to the weight of the butadiene part, 28% by weight of 1,4-cis-butadiene units relative to the weight of the butadiene part and 48% by weight of 1,4-trans-butadiene units relative to the weight of the butadiene part, Mn=120 000 g/mol and PI=1.84 measured according to the method described in paragraph 5.3) on a roll mill at 23° C. The mixture is homogenized by 15 portfolio passes. This mixing phase is followed by a heat treatment at 160° C. for 60 minutes under a press at a pressure of 10 bar.
[0231] The grafting results according to the .sup.1H NMR analysis are presented in Table 2.
5.5.2 Manufacture of a Polybutadiene Polymer Grafted with 1-(5-((2-Methyl-1H-Imidazol-1-Yl)Methyl)Furan-2-Yl)-N-Phenylmethanimine Oxide (Compound E)
[0232] 0.5 g of polybutadiene (75.4 mol % of 1,2-butadiene units and 24.6 mol % of 1,4-butadiene units; Mn=7800 g/mol and PI=1.02 measured according to the method described in paragraph 5.3) were flushed with nitrogen for 15 minutes. Next, 2 ml of dichloromethane, sparged beforehand with nitrogen for 5 minutes, were added to dissolve this polymer.
[0233] Once this polymer was dissolved, 0.265 g of 1-(5-((2-methyl-1H-imidazol-1-yl)methyl)furan-2-yl)-N-phenylmethanimine oxide (compound E) (0.94 mmol) dissolved beforehand in 2 ml of dichloromethane was added to the reaction medium with stirring. After stirring for 15 minutes, the reaction medium was left under a flush of nitrogen for 15 minutes to evaporate off the dichloromethane. Once all of the solvent was evaporated off, the reaction medium was heated to 150° C. (bath temperature) under a constant stream of nitrogen. After reaction for 10 hours 30 minutes, the reaction medium was allowed to return to room temperature (23° C.).
[0234] The grafting results according to the .sup.1H NMR analysis are presented in Table 2.
5.5.3 Manufacture of an Ethylene-Butadiene Copolymer Grafted with 1-(5-((2-Methyl-1H-Imidazol-1-Yl)Methyl)Furan-2-Yl)-N-Phenylmethanimine Oxide (Compound E)
[0235] 1-(5-((2-Methyl-1H-imidazol-1-yl)methyl)furan-2-yl)-N-phenylmethanimine oxide (0.57; 2 mmol) is incorporated into 15 g of an ethylene-butadiene copolymer EBR (containing 16.8 mol % of butadiene, 7.7 mol % of butadiene/ethylene rings and 75.5 mol % of ethylene) on a roll mill at 23° C. The mixture is homogenized by 15 portfolio passes. This mixing phase is followed by a heat treatment at 160° C. for 60 minutes under a press at a pressure of 10 bar.
[0236] The grafting results according to the .sup.1H NMR analysis are presented in Table 2.
TABLE-US-00002 TABLE 2 Targeted degree Grafted compound Elastomer (mol %) E (mol %) Grafting yield (%) BR 10 9.3 93% EBR 0.5 0.31 62% SBR 0.47 0.37 78%
5.6. Synthesis of the 1,3-Dipolar Compound N-(4-((2-Methyl-1H-Imidazol-1-Yl)Methyl)Benzylidene)Aniline Oxide (Compound E1)
[0237] This compound may be prepared in five steps according to the following reaction scheme:
##STR00022##
5.6.1 Step 1: Synthesis of Methyl 4-(Chloromethyl)Benzoate (Compound A1)
[0238] ##STR00023##
[0239] Thionyl chloride SOCl.sub.2 (2.4 ml; 32.2 mmol) is added dropwise over 10 minutes at a temperature of −8° C. (bath temperature) to 150 ml of methanol cooled to a temperature of −8° C. (bath temperature). After stirring for 5 minutes at −8° C. (bath temperature), 4-(chloromethyl)benzoic acid (5.0 g; 29.3 mmol) is added portionwise over 10 minutes at −8° C. (bath temperature). After stirring for 20 minutes at −8° C. (bath temperature), the reaction medium is heated at 14° C. (bath temperature) for 20 minutes. The reaction medium is then heated up to 50° C. (bath temperature) over 1 hour and is stirred at this temperature for 2 hours. The product solution is concentrated under reduced pressure (28 mbar, 40° C., bath temperature) to give an oil which crystallizes at room temperature.
[0240] A white solid (5.16 g, 27.9 mmol, molar yield of 95%) with a melting point of 38-40° C. is obtained.
[0241] The molar purity is greater than 95 mol % ('H NMR).
TABLE-US-00003 TABLE 3
5.6.2 Step 2: Synthesis of Methyl-4-((2-Methyl-1H-Imidazol-1-Yl)Methyl)Benzoate:
[0242] ##STR00025##
[0243] A mixture of methyl 4-(chloromethyl)benzoate (5.15 g; 28 mmol) and 2-methyl-1H-imidazole (2.52 g; 31 mmol) and K.sub.2CO.sub.3 (2.89 g; 21 mmol) in DMF (4 ml) is heated at 60° C. (bath temperature) for 1-1.5 hours, and then for 5 hours at 80° C. After cooling, the reaction medium is diluted with water at 0° C. (50 ml) and ethyl acetate (25 ml). The aqueous phase is separated out and extracted with ethyl acetate (3 times 10 ml). The combined organic phases are washed with water (3 times 5 ml). The product solution is concentrated under reduced pressure (7 mbar, 40° C., bath temperature) to give a yellow oil (4.266 g; 18.5 mmol, molar yield of 66%).
TABLE-US-00004 TABLE 4
5.6.3 Step 3: Synthesis of 4-((2-Methyl-1H-Imidazol-1-Yl)Methyl)Phenylmethanol:
[0244] ##STR00027##
[0245] A solution of LiAlH.sub.4 (1.50 g, 0.039 mol) in anhydrous THF (230 ml) is cooled to −60° C. A solution of ethyl 4-((2-methyl-1H-imidazol-1-yl)methyl)benzoate (7.80 g, 0.028 mol, 81 mol %) in anhydrous THF (100 ml) is added under argon over 15 minutes. The reaction medium is stirred 1 hour at −60° C. for and then for 10-12 hours at room temperature. Water (20 ml) is added dropwise (an exothermic reaction). The precipitate formed is filtered off and the filtrate is concentrated under reduced pressure. The crude product obtained is dissolved in CH.sub.2Cl.sub.2 (100 ml) in order to precipitate the insoluble materials. After filtering and concentrating under reduced pressure, a yellow oil (4.96 g, molar yield of 93%) is obtained. The molar purity is greater than 85% NMR).
TABLE-US-00005 TABLE 5
5.6.4 Step 4: Synthesis of 4-((2-Methyl-1H-Imidazol-1-Yl)Methyl)Benzaldehyde:
[0246] ##STR00029##
[0247] A mixture of MnO.sub.2 (6.88 g; 0.079 mol) and 4-((2-methyl-1H-imidazol-1-yl)methyl)phenylmethanol (4.57 g; 0.021 mol, 85 mol % by .sup.1H NMR) in CHCl.sub.3 (180 ml) is stirred at reflux temperature for 4 hours. The reaction medium is cooled to room temperature and is kept stirring at this temperature for 10-12 hours. The insoluble products are filtered off and the filtrate is concentrated under reduced pressure. A yellow oil (3.78 g, molar yield of 98%) is obtained after concentrating under reduced pressure. The molar purity is greater than 81% (.sup.1H NMR).
TABLE-US-00006 TABLE 6
5.6.5 Synthesis of Phenylhydroxylamine:
[0248] ##STR00031##
[0249] Phenylhydroxylamine was synthesized according to the procedure described in Org. Syntheses Coll. Vol. 1, page 445, 1941; Org. Syntheses Coll. Vol. 3, page 668, 1955.
5.6.6 Step 5: Synthesis of N-4-((2-Methyl-1H-Imidazol-1-Yl))Methyl)Benzyldiene)Aniline Oxide:
[0250] ##STR00032##
[0251] A solution of 4-((2-methyl-1H-imidazol-1-yl))methyl)benzaldehyde (3.48 g; 0.015 mol, 81 mol % by .sup.1H NMR) and phenylhydroxylamine (2.86 g; 0.026 mol) in anhydrous ethanol (20 ml) is stirred for 2 hours at 60° C. (bath temperature) and then for 12 hours at room temperature. The yellow precipitate is filtered off (0.249 g, containing the expected product). Water (30 ml) is added to the filtrate with vigorous stirring. The yellow precipitate then formed is filtered off after stirring for 20 minutes and is washed with a mixture of EtOH (10 ml) and water (20 ml) and then with water (50 ml). The two portions of solid are combined and dried under atmospheric pressure at room temperature for 10-12 hours. A yellow solid (3.71 g, molar yield 89%) with a molar purity of greater than 82% (.sup.1H NMR) is obtained. An additional purification is applied by stirring at room temperature for 1.5 hours, filtering, washing on the filter with 50 ml of ethyl ether and drying for 2 days at room temperature.
[0252] A yellow solid (3.04 g, molar yield 78%) with a melting point of 115-116° C. is obtained. The molar purity is greater than 88% (.sup.1H NMR).
TABLE-US-00007 TABLE 7
5.7. Study of the Grafting Yield of Compound E as a Function of Time
[0253] In this test, the grafting yield as a function of time of a 1,3-dipolar compound according to the invention (compound E) is compared, on a styrene/butadiene copolymer SBR, with that of a 1,3-dipolar compound of the prior art (Compound E1).
[0254] A styrene/butadiene copolymer used is an SBR containing 26.5% by weight of styrene relative to the total weight of the copolymer and in its butadiene part, relative to the weight of the butadiene part, 24% by weight of 1,2-butadiene units, 28% by weight of 1,4-cis-butadiene units and 48% by weight of 1,4-trans-butadiene units relative to the weight of the butadiene part. Its Mn is equal to 120 000 g/mol and its PI is equal to 1.84; they are measured according to the method described in paragraph 3.
[0255] The process is performed in the following manner:
[0256] 1-(5-((2-Methyl-1H-imidazol-1-yl)methyl)furan-2-yl)-N-phenylmethanimine oxide (0.27 g, 0.97 mmol) (compound E according to the invention) or N-(4-((2-methyl-1H-imidazol-1-yl)methyl)benzylidene)aniline oxide (compound E1 not in accordance) (0.28 g, 0.97 mmol) is incorporated into 15 g of SBR as described above on a roll mill at 23° C. The mixture is homogenized by 15 portfolio passes. This mixing phase is followed by a heat treatment at 160° C. for 15 minutes under a press at a pressure of 10 bar.
[0257] The same experiment is performed for grafting times of 30 minutes and 60 minutes.
[0258] At the end of each experiment, the molar degree of grafting of compound E, in accordance with the invention, or of compound E1, not in accordance with the invention, is determined analytically by .sup.1H NMR in accordance with the method described in paragraph 2. The results are collated in Table 8.
TABLE-US-00008 TABLE 8 Grafting yield (%) Grafting time 15 min 30 min 60 min Compound E 60 67 78 Compound E1 44 46 44
[0259] Surprisingly, it is seen from Table 8 that the grafting yield of compound E in accordance with the invention is always significantly improved relative to compound E1 not in accordance with the invention. In addition, the grafting yield of compound E in accordance with the invention continues to increase beyond the 30 minutes of reaction, whereas a plateau is reached within 15 minutes for compound E1 not in accordance with the invention.