STEREOBLOCK DIENE COPOLYMERS AND PREPARATION PROCESS THEREOF

Abstract

The invention relates to isoprene and butadiene and/or pentadiene stereoblock copolymers in which the different stereoregular blocks, joined to each other by means of a single junction point, have different structures and thermal properties. The invention also relates to a process for the preparation of the aforesaid copolymers which comprises the formation of stereoblocks in successive steps but in the presence of a single catalytic system obtained from cobalt dichloride, a phosphine and an organic compound of aluminum.

Claims

1-22. (canceled)

23. A composition of stereoblock copolymers having a general formula (I) ##STR00004## wherein: PI is a 1,4-cis/3,4 polyisoprene block with an alternating structure; PB is a polybutadiene block with a syndiotactic 1,2 structure in which the content in 1,2 units is 80%; PP is a polypentadiene block with a syndiotactic 1,2 structure in which the content in 1,2 units is 90%; m, n, and z are equal to 1 or equal to 0 according to the following conditions: m and n are simultaneously equal to 1 or alternatively m is equal to 1 and n is equal to zero, or m is equal to 0 and n is equal to 1; if m is equal to 1, z is equal to 0 and n is equal to 1 or 0; if m is equal to 0, n is equal to 1, and z is equal to 1 or equal to 0.

24. The stereoblock copolymers according to claim 23, wherein m is equal to 0 and n is equal to 1 and z is equal to 0, having general formula (II):
PI-PB(II)

25. The stereoblock copolymers according to claim 23, wherein m is equal to 1 and n and z are equal to 0, having general formula (III):
PI-PP(III)

26. The stereoblock copolymers according to claim 23, in which m is equal to 1 and n is equal to 1 and z is equal to 0, having general formula (IV):
PP-PI-PB(IV)

27. The stereoblock copolymers according to claim 23, wherein m is equal to 0, n is equal to 1 and z is equal to 1, having general formula (V):
PB-PI-PB(V)

28. The stereoblock copolymers according to claim 23, wherein the polyisoprene block is present in a molar amount of from 10% to 90%.

29. The stereoblock copolymers according to claim 23, comprising a polydispersity index from 1.5 to 2.3.

30. The stereoblock copolymers according to claim 23, wherein the polyisoprene block has a glass transition temperature from 10 C. to 30 C.

31. The stereoblock copolymers according to claim 23, wherein the polyisoprene block is amorphous from 20 C. to 25 C.

32. The stereoblock copolymers according to claim 23, wherein the polybutadiene block has a glass transition temperature from 10 C. to 24 C.

33. The stereoblock copolymers according to claim 23, wherein the polybutadiene block has a melting point from 70 C. to 140 C.

34. The stereoblock copolymers according to claim 23, wherein the polybutadiene block has a crystallization temperature from 55 C. to 130 C.

35. The stereoblock copolymers according to claim 23, wherein the polybutadiene block has a content of syndiotactic triads from 15% to 90%.

36. The stereoblock copolymers according to claim 23, wherein the polypentadiene block has a glass transition temperature from 12 C. to 25 C.

37. The stereoblock copolymers according to claim 23, wherein the polypentadiene block has a melting point from 80 C. to 160 C.

38. The stereoblock copolymers according to claim 23, wherein the polypentadiene block has a crystallization temperature from 60 C. to 135 C.

39. The stereoblock copolymers according to claim 23, wherein the polypentadiene block has a content of syndiotactic triads comprised from 15% to 90%.

40. A process for preparation of the stereoblock copolymer composition according to claim 23, comprising: a) subjecting to total stereospecific polymerization a first monomer selected from isoprene, pentadiene or butadiene in the presence of a catalytic system obtained from cobalt dichloride, a phosphine of general formula (VI)
R.sub.mP-Ph.sub.n(VI) wherein m=0, 1, 2 and n=1, 2, 3, and wherein: P is trivalent phosphorus; R is selected from linear or branched C.sub.1-C.sub.20 alkyl or C.sub.3-C.sub.30 cycloalkyl; Ph is a phenyl group of formula (VII) ##STR00005## wherein R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are independently selected from the group consisting of H and C.sub.1-C.sub.6 alkyl, and a co-catalyst selected from the aluminum compounds of general formula (VIII) or of general formula (IX), wherein general formula (VIII) is
Al(X).sub.n(R.sub.6).sub.3-n(VIII) wherein n=0, 1, 2 and wherein X represents a halogen atom selected from the group consisting of chlorine, bromine, iodine, and fluorine, and wherein R.sub.6 is selected from the group consisting of linear or branched C.sub.1-C.sub.20 alkyl, cycloalkyl, and aryl, all optionally substituted with one or more silicon or germanium atoms; wherein general formula (IX) is
(R.sub.7).sub.2AlO[Al(R.sub.8)O-].sub.p-Al(R.sub.9).sub.2(IX) wherein p is an integer from 0 to 1000 and wherein R.sub.7, R.sub.8 and R.sub.9, are independently selected from the group consisting of hydrogen, chlorine, bromine, iodine, fluorine, linear or branched C.sub.1-C.sub.20 alkyl optionally substituted with one or more silicon or germanium atoms, cycloalkyl optionally substituted with one or more silicon or germanium atoms, and aryl optionally substituted with one or more silicon or germanium atoms; so as to obtain a first stereoblock consisting of units of said first monomer; b) in the presence of the first stereoblock, subjecting to total stereospecific polymerization a second monomer different from the first monomer, the second monomer selected from isoprene, pentadiene or butadiene, provided that if the first monomer consists of butadiene or pentadiene, the second monomer consists of isoprene, so as to obtain a second stereoblock consisting solely of units of said second monomer, wherein the second stereoblock is joined to the first stereoblock in a single junction point.

41. The process according to claim 40, further comprising: c) in the presence of the first and second stereoblocks in which the second stereoblock consists of isoprene, subjecting a third monomer selected from pentadiene or butadiene to total stereospecific polymerization so as to obtain a third stereoblock consisting solely of units of said third monomer, wherein the third stereoblock is joined to the second stereoblock in a single junction point; with the exclusion of pentadiene as a third stereoblock when the first stereoblock consists of pentadiene units; wherein in steps b) and c) the polymerization is carried out in the presence of the same catalytic system of step a).

42. The process according to claim 40, carried out in the presence of an inert organic solvent selected from the group consisting of: saturated aliphatic hydrocarbons and mixtures thereof; saturated cycloaliphatic hydrocarbons and mixtures thereof; mono-olefins and mixtures thereof; aromatic hydrocarbons and mixtures thereof; halogenated hydrocarbons and mixtures thereof.

Description

[0237] Characteristics and advantages of the invention will be more apparent from the description of preferred embodiments, illustrated by way of example in the accompanying drawings; wherein:

[0238] FIGS. 1a/1b/1c show AFM images of the butadiene/isoprene stereoblock copolymer of example 7;

[0239] FIGS. 2a/2b/2c show AFM images of a mechanical mixture consisting of syndiotactic 1,2 polybutadiene/alternating cis-1,4/3,4 polyisoprene;

[0240] FIG. 3 shows .sup.13C-NMR spectra of polybutadienes with different degrees of syndiotacticity;

[0241] FIG. 4 shows .sup.1H NMR spectra of isoprene/butadiene stereoblock copolymers;

[0242] FIG. 5 shows .sup.13C NMR spectra of the syndiotactic 1,2 polypentadiene of example 2;

[0243] FIG. 6 shows .sup.1H NMR spectra of the isoprene-pentadiene stereoblock copolymer of example 13;

[0244] FIG. 7 shows AFM images of the butadiene/isoprene/butadiene terpolymer of Ex. 16;

[0245] FIG. 8 shows FT-IR of the polypentadiene of example 2;

[0246] FIG. 9a shows .sup.1H NMR of the polypentadiene of example 2;

[0247] FIG. 9b shows .sup.13C NMR of the polypentadiene of example 2;

[0248] FIG. 10 shows FT-IR of the polyisoprene of example 3;

[0249] FIG. 11a shows .sup.1H NMR of the polyisoprene of example 3;

[0250] FIG. 11b shows .sup.13C NMR of the polyisoprene of example 3;

[0251] FIG. 12 shows FT-IR of the polybutadiene of example 4;

[0252] FIG. 13a shows .sup.1H NMR of the polybutadiene of example 4;

[0253] FIG. 13b shows .sup.13C NMR of the polybutadiene of example 4;

[0254] FIG. 14 shows FT-IR of the copolymer of example 5;

[0255] FIG. 15a shows .sup.1H NMR of the copolymer of example 5;

[0256] FIG. 15b shows .sup.13C NMR of the copolymer of example 5;

[0257] FIG. 16 shows DSC of the copolymer of example 5;

[0258] FIG. 17 shows FT-IR of the copolymer of example 6;

[0259] FIG. 18a shows .sup.1H NMR of the copolymer of example 6;

[0260] FIG. 18b shows .sup.13C NMR of the copolymer of example 6;

[0261] FIG. 19 shows DSC of the copolymer of example 6;

[0262] FIG. 20 shows FT-IR of the copolymer of example 7;

[0263] FIG. 21a shows .sup.1H NMR of the copolymer of example 7;

[0264] FIG. 21b shows .sup.13C NMR of the copolymer of example 7;

[0265] FIG. 22 shows DSC of the copolymer of example 7;

[0266] FIG. 23 shows FT-R of the copolymer of example 8;

[0267] FIG. 24a shows .sup.1H NMR of the copolymer of example 8;

[0268] FIG. 24b shows .sup.13C NMR of the copolymer of example 8;

[0269] FIG. 25 shows FT-IR of the copolymer of example 9;

[0270] FIG. 26a shows .sup.1H NMR of the copolymer of example 9;

[0271] FIG. 26b shows .sup.13C NMR of the copolymer of example 9;

[0272] FIG. 27 shows FT-IR of the copolymer of example 10;

[0273] FIG. 28a shows .sup.1H NMR of the copolymer of example 10;

[0274] FIG. 28b shows .sup.13C NMR of the copolymer of example 10;

[0275] FIG. 29 shows DSC of the copolymer of example 10;

[0276] FIG. 30 shows FT-IR of the copolymer of example 11;

[0277] FIG. 31a shows .sup.1H NMR of the copolymer of example 11;

[0278] FIG. 31b shows .sup.13C NMR of the copolymer of example 11;

[0279] FIG. 32 shows FT-IR of the copolymer of example 12;

[0280] FIG. 33a shows .sup.1H NMR of the copolymer of example 12;

[0281] FIG. 33b shows .sup.13C NMR of the copolymer of example 12;

[0282] FIG. 34 shows FT-IR of the copolymer of example 13;

[0283] FIG. 35a shows .sup.1H NMR of the copolymer of example 13;

[0284] FIG. 35b shows .sup.13C NMR of the copolymer of example 13;

[0285] FIG. 36 shows FT-IR of the copolymer of example 14;

[0286] FIG. 37a shows .sup.1H NMR of the copolymer of example 14;

[0287] FIG. 37b shows .sup.13C NMR of the copolymer of example 14;

[0288] FIG. 38 shows FT-IR of the copolymer of example 15;

[0289] FIG. 39a shows .sup.1H NMR of the copolymer of example 15;

[0290] FIG. 39b shows .sup.13C NMR of the copolymer of example 15;

[0291] FIG. 40 shows FT-IR of the copolymer of example 16;

[0292] FIG. 41a shows .sup.1H NMR of the copolymer of example 16;

[0293] FIG. 41b shows .sup.13C NMR of the copolymer of example 16;

[0294] FIG. 42 shows DSC of the copolymer of example 16;

[0295] FIG. 43 shows FT-IR of the copolymer of example 17;

[0296] FIG. 44a shows .sup.1H NMR of the copolymer of example 17;

[0297] FIG. 44b shows .sup.13C NMR of the copolymer of example 17;

[0298] FIG. 45 shows DSC of the copolymer of example 17;

[0299] FIGS. 46a and 46b show .sup.13C NMR of the copolymer of Example 6 according to the invention and the copolymer of Example 18 of US 2020/0109229 A1: and

[0300] FIG. 47 shows AFM images of a mixture of the copolymer of Example 6 according to the invention and natural rubber (example 18).

EXAMPLES

[0301] Reagents and Materials

[0302] The reagents and materials used in the subsequent examples of the invention are listed below, together with their optional pretreatments and their manufacturer: [0303] cobalt dichloride (CoCl.sub.2) (Strem Chemicals): used as is; [0304] pentane (Aldrich): pure, 99.5%, distilled on sodium (Na) in inert atmosphere; [0305] 1,3-butadiene (Air Liquide): pure, 99.5%, evaporated from the container before each production, dried by passing through a column packed with molecular sieves and condensed inside the reactor pre-cooled to 20 C.; [0306] isoprene (Aldrich): pure, 99.5%, refluxed with calcium hydride (CaH.sub.2) for around 2 h, then distilled trap-to-trap and kept refrigerated in an inert atmosphere; [0307] (E)-1,3-pentadiene (Aldrich): pure, 99%, refluxed with calcium hydride (CaH.sub.2) for around 2 h, then distilled trap-to-trap and kept refrigerated in an inert atmosphere; [0308] toluene (Aldrich): pure, 99.5%, distilled on sodium (Na) in an inert atmosphere; [0309] methylene chloride (Sigma-Aldrich, purification grade) [0310] methylaluminoxane (MAO) (toluene solution at 10% by weight) (Aldrich): used as is; [0311] methyldiphenylphosphine (Strem, 99% pure); [0312] dimethylphenylphosphine (Strem, 99% pure); [0313] ethyldiphenylphosphine (Aldrich, 98% pure); [0314] diethylphenylphosphine (Aldrich, 96% pure); [0315] normal-propyldiphenylphosphine (Aldrich, 98% pure); [0316] iso-propyldiphenylphosphine (Aldrich, 97% pure); [0317] tert-butyldiphenylphosphine (Strem); [0318] allyldiphenylphosphine (Aldrich, 95% pure); [0319] diallylphenylphosphine (Aldrich, 95% pure); [0320] cyclohexyldiphenylphosphine (Strem, 98% pure); [0321] dicyclohexylphenylphosphine (Aldrich, 95% pure); [0322] deuterated tetrachloroethane (C.sub.2D.sub.2Cl.sub.4) (Acros): used as is; [0323] deuterated chloroform (CDCl.sub.3) (Acros): used as is.

[0324] Analysis and Characterization Methods

[0325] .sup.13C-NMR and .sup.1H-NMR Spectra

[0326] The .sup.13C-NMR and .sup.1H-NMR spectra were recorded by means of a nuclear magnetic resonance spectrometer mod. Bruker Avance 400, using deuterated tetrachloroethane (C.sub.2D.sub.2Cl.sub.4) at 103 C., and hexamethyldisiloxane (HDMS) as internal standard, or using deuterated chloroform (CDCl.sub.3), at 25 C., and tetramethylsilane (TMS) as internal standard. For this purpose, polymeric solutions having concentrations equal to 10% by weight with respect to the total weight of the polymeric solution were used.

[0327] The microstructure of the stereoblock copolymers and terpolymers (i.e., content of isoprene, butadiene and pentadiene units, content of cis-1,4 and 3,4 units of the isoprene block, content of 1,2 units (%) and content of syndiotactic triads [(rr) (%) of the butadiene block and of the pentadiene block], was determined by analysis of the aforesaid spectra based on the indications provided in the literature by Mochel, V. D., in Journal of Polymer Science Part A-1: Polymer Chemistry (1972), Vol. 10, Issue 4, pages 1009-1018, for polybutadiene; and by Sato, H., et al., in Journal of Polymer Science: Polymer Chemistry Edition (1979), Vol. 17, Issue 11, pages 3551-3558 for polyisoprene, by a) Beebe, D. H.; Gordon, C. E.; Thudium, R. N.; Throckmorton, M. C.; Hanlon, T. L. J. Polym. Sci: Polym. Chem. And. 1978, 16, 2285; b) Ciampelli, F.; Lachi, M. P.; Tacchi Venturi, M.; Porri, L. Eur. Polym. J. 1967, 3, 353 and G. Ricci, T. Motta, A. Boglia, E. Alberti, L. Zetta, F. Bertini, P. Arosio, A. Famulari, S. V. Meille Synthesis, characterization and crystalline structure of syndiotactic 1,2 polypentadiene: the trans polymer. Macromolecules 2005, 38, 8345-8352 for polypentadiene.

[0328] I.R. Spectra

[0329] The I.R. spectra (FT-IR) were recorded by means of Thermo Nicolet Nexus 670 and Bruker IFS 48 spectrophotometers.

[0330] The I.R. spectra (FT-IR) of the polymers were obtained by polymer films on potassium bromide tablets (KBr), said film being obtained by deposition of a solution on the polymer to be analyzed in hot o-dichlorobenzene. The concentration of the polymer solutions analyzed was equal to 10% by weight with respect to the total weight of the polymeric solution.

[0331] Thermal Analysis (DSC)

[0332] DSC (Differential Scanning Calorimetry) thermal analysis, for the purpose of determining the melting point (T.sub.m), the glass transition temperature (T.sub.g) and the crystallization temperature (T.sub.c) of the polymers obtained, was carried out by means of a differential scanning calorimeter DSC Q1000 by TA Instruments.

[0333] Molecular Weight Determination

[0334] Determination of the molecular weight (MW) and dispersion (Mw/Mn) of the polymers obtained was carried out with a Waters GPCV 2000 system, using two lines of detectors (differential viscometer and refractometer), operating under the following experimental conditions. The experimental conditions were: [0335] two PLgel Mixed-C columns; [0336] solvent/eluent: o-dichlorobenzene (Aldrich); [0337] flow: 0.8 ml/min; [0338] temperature: 145 C.; [0339] molecular mass calculation: Universal Calibration method.

[0340] The weight average molecular weight (M.sub.w) and the polydispersion index (PDI) corresponding to the ratio M.sub.w/M.sub.n(M.sub.n=number average molecular weight) are reported.

[0341] Atomic Force Microscopy (MFA)

[0342] For this purpose, a thin film of stereoregular diblock polybutadiene to be analyzed was prepared, by depositing a solution in chloroform, or in toluene, of said stereoregular diblock polybutadiene by means of spin-coating on a silicon substrate.

[0343] The analysis was carried out without dynamic contact (non contact mode or tapping mode), using an NTEGRA Spectra atomic force microscope (AFM) of N-MDT. During scanning of the surface of said thin film, the variations in amplitude of the oscillations of the tip provide topographical information relating to the surface of the same (HEIGHT image). Moreover, the phase variations of the oscillations of the tip can be used to distinguish between different types of materials present on the surface of said film (different phases of the material).

[0344] By way of example, FIGS. 1a/1b/1c shows the AFM image of the butadiene/isoprene stereoblock copolymer obtained as described in Example 7. FIGS. 2a/2b/2c, for comparison, shows the AFM image of the mechanical mixture consisting of syndiotactic 1,2 polybutadiene/alternating cis-1,4/3,4 polyisoprene (40/60), and prepared as described below.

Preparation of Syndiotactic 1,2 Polybutadiene/Alternating Cis-1,4/3,4 Polyisoprene Mechanical Mixture

[0345] 2 grams of polyisoprene with a perfectly alternating cis-1,4/3,4 structure obtained as described in Example 3 and 1.04 grams of polybutadiene with a syndiotactic 1,2 structure obtained as described in Example 4 are introduced into a 250 ml flask and dissolved in toluene using heat. After being completely dissolved, the polymers are re-precipitated in a large excess of methanol, filtered and then dried under vacuum at room temperature for a whole night. The polymer thus obtained is used as is for AFM analysis.

Example 1

Preparation of the Catalyst or Precatalyst Component (1a-d)

[0346] 0.13 grams of anhydrous CoCl.sub.2 (110.sup.3 moles) are dissolved in methylene chloride (30 ml) in a 100 ml flask; isopropyldiphenylphosphine (P.sup.iPrPh.sub.2) (310.sup.3 moles; 0.685 grams) is then introduced and kept under stirring at room temperature for around 3 hours. The blue solution thus obtained (1 ml110.sup.4 moles of Co) (1a) is used in the amount indicated in the examples of co- and terpolymerization. The other catalytic components, or precatalyzers, which use different phosphines from P.sup.iPrPh.sub.2 are prepared in exactly the same way. Therefore, in the case of the use of tert-butyldiphenylphosphine (P.sup.tBuPh.sub.2) (310.sup.3 moles; 0.727 grams), cyclohexyldiphenylphosphine (PCyPh.sub.2) (310.sup.3 moles; 0.805 grams) and triphenylphosphine (PPh.sub.3) (310.sup.3 moles; 0.787 grams) the solutions (1b), (1c), and (1d) are obtained, respectively.

Example 2

Synthesis of Syndiotactic 1,2 Polypentadiene (Reference Homopolymer)

[0347] 2 ml of (E)-1,3-pentadiene equal to 1.36 g was introduced into a 50 ml test-tube. 20 ml of heptane was subsequently added and the temperature of the solution thus obtained was taken to 25 C. Methylaluminoxane (MAO) in a toluene solution (1.89 ml; 310.sup.3 moles, equal to about 0.174 g) was then added and, subsequently, the solution prepared as in example 1a (0.3 ml; 310.sup.5 moles of Co), (molar ratio Al/Co=100). The whole mixture was kept under magnetic stirring at 25 C. for 90 minutes. The polymerization was then quenched by adding 2 ml of methanol. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of antioxidant Irganox 1076 (Ciba) obtaining 1.36 g of polypentadiene, with a conversion equal to 100% and having a syndiotactic 1,2 structure. Further characteristics of the process and of the polypentadiene obtained are set down in Table 1.

[0348] FIG. 8 shows the FT-IR spectrum of the polypentadiene obtained.

[0349] FIG. 9 shows the .sup.1H and .sup.13C NMR spectra.

Example 3

Synthesis of Alternating Cis-1,4/3,4 Polyisoprene (Reference Homopolymer)

[0350] 5 ml di isoprene equal to 3.4 g was introduced into a 50 ml test-tube. 20 ml of heptane was subsequently added and the temperature of the solution thus obtained was taken to 25 C. Methylaluminoxane (MAO) in toluene solution (1.89 ml; 310.sup.3 moles, equal to about 0.174 g) was then added and, subsequently, the solution prepared as in example 1a (0.3 ml; 310.sup.5 moles of Co) (molar ratio Al/Co=100). The whole mixture was kept under magnetic stirring at 25 C. for 180 minutes. The polymerization was then quenched by adding 2 ml of methanol. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of antioxidant Irganox 1076 (Ciba) obtaining 3.4 g di polyisoprene having a perfectly alternating cis-1,4/3,4 structure, with a conversion equal to 100%. Further characteristics of the process and of the polyisoprene obtained are set down in Table 1.

[0351] FIG. 10 shows the FT-IR spectrum of the polyisoprene obtained.

[0352] FIG. 11 shows the .sup.1H and .sup.13C NMR spectra.

Example 4

Synthesis of Syndiotactic 1,2 Polybutadiene (Reference Homopolymer)

[0353] 2 ml of 1,3-butadiene equal to about 1.4 g was condensed at a low temperature (20 C.) in a 25 ml test-tube. 14.4 ml di toluene was subsequently added and the temperature of the solution thus obtained was taken to 25 C. Methylaluminoxane (MAO) in toluene solution (0.63 ml; 110.sup.3 moles, equal to about 0.058 g) was then added and, subsequently, the solution prepared as in example 1a (0.1 ml; 110.sup.5 moles of Co) (molar ratio Al/Co=100). The whole mixture was kept under magnetic stirring at 25 C. for 30 minutes. The polymerization was then quenched by adding 2 ml of methanol. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of antioxidant Irganox 1076 (Ciba) obtaining 1.4 g of polybutadiene with a syndiotactic 1,2 structure, with a conversion equal to 100%. Further characteristics of the process and of the syndiotactic 1,2 polybutadiene obtained are set down in Table 1.

[0354] FIG. 12 shows the FT-IR spectrum of the syndiotactic 1,2 polybutadiene obtained.

[0355] FIG. 13 shows the .sup.1H and .sup.13C NMR spectra of the syndiotactic 1,2 polybutadiene.

Example 5

Synthesis of Isoprene/Butadiene Stereoregular Copolymer with an Alternating 1,4-Cis/3,4 Structure for the Polyisoprene Block and a Syndiotactic 1,2 Structure for the Polybutadiene Block (Invention)

[0356] 5 ml di isoprene equal to 3.4 g was introduced into a 50 ml test-tube. 20 ml of heptane was subsequently added and the temperature of the solution thus obtained was taken to 25 C. Methylaluminoxane (MAO) in toluene solution (1.89 ml; 310.sup.3 moles, equal to about 0.174 g) was then added and, subsequently, the solution prepared as described in example 1d (0.3 ml; 310.sup.5 moles of Co) (molar ratio Al/Co=100). The whole mixture was kept under magnetic stirring at 25 C. for 150 minutes and 0.5 ml of butadiene (0.35 g) dissolved in heptane (4.5 ml) was then added. The polymerization was left to proceed for a further 60 minutes and then quenched by adding 2 ml of methanol. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of antioxidant Irganox 1076 (Ciba) obtaining 3.61 g of isoprene/butadiene copolymer, with a conversion equal to 97% relative to the total amount of charged monomers. Further characteristics of the process and of the isoprene-butadiene copolymer obtained are set down in Table 1.

[0357] FIG. 14 shows the FT-IR spectrum of the isoprene-butadiene stereoregular copolymer obtained.

[0358] FIG. 15 shows the .sup.1H and .sup.13C NMR spectra.

[0359] FIG. 16 shows the DSC curve.

Example 6

Synthesis of Isoprene/Butadiene Stereoregular Copolymer with an Alternating 1,4-Cis/3,4 Structure for the Polyisoprene Block and a Syndiotactic 1,2 Structure for the Polybutadiene Block (Invention)

[0360] 5 ml di isoprene equal to 3.4 g was introduced into a 50 ml test-tube. 20 ml of heptane was subsequently added and the temperature of the solution thus obtained was taken to 25 C. Methylaluminoxane (MAO) in toluene solution (1.89 ml; 310.sup.3 moles, equal to about 0.174 g) was then added and, subsequently, the solution prepared as in example 1d (0.3 ml; 310.sup.5 moles of Co) (molar ratio Al/Co=100). The whole mixture was kept under magnetic stirring at 25 C., for 150 minutes, then 1.5 ml of butadiene (1.05 g) dissolved in heptane (13.5 ml) was added. The polymerization was left to proceed for a further 60 minutes and then quenched by adding 2 ml of methanol. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of antioxidant Irganox 1076 (Ciba) obtaining 4.36 g of isoprene/butadiene copolymer, with a conversion equal to 96.8% relative to the total amount of charged monomers. Further characteristics of the process and of the copolymer isoprene-butadiene obtained are set down in Table 1.

[0361] FIG. 17 shows the FT-IR spectrum of the isoprene-butadiene stereoregular copolymer obtained.

[0362] FIG. 18 shows the .sup.1H and .sup.13C NMR spectra.

[0363] FIG. 19 shows the DSC curve.

Example 7

Synthesis of Isoprene/Butadiene Stereoregular Copolymer with an Alternating 1,4-Cis/3,4 Structure for the Polyisoprene Block and a Syndiotactic 1,2 Structure for the Polybutadiene Block (Invention)

[0364] 5 ml of isoprene equal to 3.4 g was introduced into a 50 ml test-tube. 20 ml of heptane was subsequently added and the temperature of the solution thus obtained was taken to 25 C. Methylaluminoxane (MAO) in toluene solution (1.89 ml; 310.sup.3 moles, equal to about 0.174 g) was then added and, subsequently, the solution prepared as in example 1c (0.3 ml; 310.sup.5 moles of Co) (molar ratio Al/Co=100). The whole mixture was kept under magnetic stirring at 25 C., for 100 minutes, then 2.5 ml of butadiene (1.75 g) dissolved in heptane (22.5 ml) was added. The polymerization was left to proceed for a further 60 minutes and then quenched by adding 2 ml of methanol. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of antioxidant Irganox 1076 (Ciba) obtaining 5.10 g of isoprene-butadiene copolymer, with a conversion equal to 99.1% relative to the total amount of charged monomers. Further characteristics of the process and of the copolymer isoprene-butadiene obtained are set down in Table 1.

[0365] FIG. 20 shows the FT-IR spectrum of the isoprene-butadiene stereoregular copolymer obtained.

[0366] FIG. 21 shows the .sup.1H and .sup.13C NMR spectra.

[0367] FIG. 22 shows the DSC curve.

Example 8

Synthesis of Copolymer Butadiene/Isoprene Stereoregular with an Alternating 1,4-Cis/3,4 Structure for the Polyisoprene Block and a Syndiotactic 1,2 Structure for the Polybutadiene Block (Invention)

[0368] 1.5 ml of butadiene equal to 1.05 g was condensed at a low temperature (20 C.) in a 50 ml test-tube. 20.7 ml of heptane was subsequently added and the temperature of the solution thus obtained was taken to 25 C. Methylaluminoxane (MAO) in toluene solution (1.26 ml; 210.sup.3 moles, equal to about 0.116 g) was then added and, subsequently, the solution prepared as in example 1a (0.2 ml; 210.sup.5 moles of Co) (molar ratio Al/Co=100). The whole mixture was kept under magnetic stirring at 25 C. for 7 minutes, then 5 ml of isoprene (3.4 g) was added. The polymerization was left to proceed for a further 120 minutes and then quenched by adding 2 ml of methanol. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of antioxidant Irganox 1076 (Ciba) obtaining 4.27 g of butadiene/isoprene copolymer, with a conversion equal to 95.1% relative to the total amount of charged monomers. Further characteristics of the process and of the butadiene/isoprene copolymer obtained are set down in Table 1.

[0369] FIG. 23 shows the FT-IR spectrum of the butadiene-isoprene stereoregular copolymer obtained.

[0370] FIG. 24 shows the .sup.1H and .sup.13C NMR spectra.

Example 9

Synthesis of Butadiene/Isoprene Stereoregular Copolymer with an Alternating 1,4-Cis/3,4 Structure for the Polyisoprene Block and a Syndiotactic 1,2 Structure for the Polybutadiene Block (Invention)

[0371] 2.0 ml of butadiene equal to 1.4 g was condensed at a low temperature (20 C.) in a 50 ml test-tube. 25 ml of heptane was subsequently added and the temperature of the solution thus obtained was taken to 25 C. Methylaluminoxane (MAO) in toluene solution (1.26 ml; 210.sup.3 moles, equal to about 0.116 g) was then added and, subsequently, the solution prepared as in example 1a (0.2 ml; 210.sup.5 moles of Co) (molar ratio Al/Co=100). The whole mixture was kept under magnetic stirring at 25 C., for 18 minutes, then 8 ml of isoprene (5.44 g) was added. The polymerization was left to proceed for a further 360 minutes and then quenched by adding 2 ml of methanol. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of antioxidant Irganox 1076 (Ciba) obtaining 6.6 g of butadiene/isoprene copolymer, with a conversion equal to 97.5% relative to the total amount of charged monomers. Further characteristics of the process and of the butadiene/isoprene copolymer obtained are set down in Table 1.

[0372] FIG. 25 shows the FT_IR spectrum of the copolymer butadiene isoprene diblock stereoregular obtained.

[0373] FIG. 26 shows the .sup.1H and .sup.13C NMR.

Example 10

Synthesis of Butadiene/Isoprene Stereoregular Copolymer with an Alternating 1,4-Cis/3,4 Structure for the Polyisoprene Block and a Syndiotactic 1,2 Structure for the Polybutadiene Block (Invention)

[0374] 1.0 ml of butadiene equal to 0.7 g was condensed at a low temperature (30 C.) in a 50 ml test-tube. 25 ml of heptane was subsequently added and the temperature of the solution was taken to the temperature of 25 C. Methylaluminoxane (MAO) in toluene solution (1.26 ml; 210.sup.3 moles, equal to about 0.116 g) was then added and, subsequently, the solution prepared as in example 1b (0.2 ml; 210.sup.5 moles of Co) (molar ratio Al/Co=100). The whole mixture was kept under magnetic stirring at 25 C., for 15 minutes; 8 ml of isoprene (5.44 g) was then added. The polymerization was left to proceed for a further 300 minutes and then quenched by adding 2 ml of methanol. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of antioxidant Irganox 1076 (Ciba) obtaining 5.9 g of butadiene/isoprene copolymer, with a conversion equal to 96.7% relative to the total amount of charged monomers. Further characteristics of the process and of the butadiene/isoprene copolymer obtained are set down in Table 1.

[0375] FIG. 27 shows the FT-IR spectrum of the butadiene-isoprene stereoregular copolymer obtained.

[0376] FIG. 28 shows the .sup.1H and .sup.13C NMR spectra.

[0377] FIG. 29 shows the DSC curve.

Example 11

Synthesis of Butadiene/Isoprene Stereoregular Copolymer with an Alternating 1,4-Cis/3,4 Structure with Regard to the Polyisoprene Block and a Syndiotactic 1,2 Structure with Regard to the Polybutadiene Block (Invention)

[0378] 4 ml of butadiene equal to 2.8 g was condensed at a low temperature (30 C.) in a 50 ml test-tube. 25 ml of heptane was subsequently added and the temperature of the solution was taken to the temperature of 25 C. Methylaluminoxane (MAO) in toluene solution (0.63 ml; 110.sup.3 moles, equal to about 0.058 g) was then added and, subsequently, the solution prepared as in example 1a (0.1 ml; 110.sup.5 moles of Co) (molar ratio Al/Co=100). The whole mixture was kept under magnetic stirring for 200 minutes, then 5 ml of isoprene (3.4 g) was added. The polymerization was left to proceed for a further 300 minutes and then quenched by adding 2 ml of methanol. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of antioxidant Irganox 1076 (Ciba) obtaining 6.0 g of butadiene/isoprene copolymer, with a conversion equal to 96.8% relative to the total amount of charged monomers. Further characteristics of the process and of the butadiene/isoprene stereoregular copolymer obtained are set down in Table 1.

[0379] FIG. 30 shows the FT-IR spectrum of the butadiene-isoprene stereoregular copolymer obtained.

[0380] FIG. 31 shows the .sup.1H and .sup.13C NMR spectra.

Example 12

Synthesis of Isoprene/Pentadiene Stereoregular Copolymer with an Alternating 1,4-Cis/3,4 Structure for the Polyisoprene Block and a Syndiotactic 1,2 Structure for the Polypentadiene Block (Invention)

[0381] 4 ml di isoprene equal to 2.72 g was introduced into a 50 ml test-tube. 20 ml of heptane was subsequently added and the temperature of the solution thus obtained was taken to 25 C. Methylaluminoxane (MAO) in toluene solution (1.89 ml; 310.sup.3 moles, equal to about 0.174 g) was then added and, subsequently, the solution prepared as described in example 1a (0.3 ml; 310.sup.5 moles of Co) (molar ratio Al/Co=100). The whole mixture was kept under magnetic stirring at 25 C. for 150 minutes, then 1 ml of E-1,3-pentadiene (0.68 g) dissolved in heptane (4 ml) was added. The polymerization was left to proceed for a further 120 minutes and then quenched by adding 2 ml of methanol. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of antioxidant Irganox 1076 (Ciba) obtaining 3.33 g of isoprene/pentadiene copolymer, with a conversion equal to 97.9% relative to the total amount of charged monomers. Further characteristics of the process and of the isoprene/pentadiene copolymer obtained are set down in Table 1.

[0382] FIG. 32 shows the FT_IR spectrum of the isoprene/pentadiene stereoregular diblock copolymer obtained.

[0383] FIG. 33 shows the .sup.1H and .sup.13C NMR spectra.

Example 13

Synthesis of Isoprene/Pentadiene Stereoregular Copolymer with an Alternating 1,4-Cis/3,4 Structure for the Polyisoprene Block and a Syndiotactic 1,2 Structure for the Polypentadiene Block (Invention)

[0384] 3 ml di isoprene equal to 2.04 g was introduced into a 50 ml test-tube. 20 ml of heptane was subsequently added and the temperature of the solution thus obtained was taken to 25 C. Methylaluminoxane (MAO) in toluene solution (1.89 ml; 310.sup.3 moles, equal to about 0.174 g) was then added and, subsequently, the solution prepared as described in example 1a (0.3 ml; 310.sup.5 moles of Co) (molar ratio Al/Co=100). The whole mixture was kept under magnetic stirring at 25 C., for 150 minutes, then 2 ml of E-1,3-pentadiene (1.36 g) dissolved in heptane (2.5 ml) was added. The polymerization was left to proceed for a further 120 minutes and then quenched by adding 2 ml of methanol. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of antioxidant Irganox 1076 (Ciba) obtaining 3.22 g of isoprene/pentadiene copolymer, with a conversion equal to 97.70% relative to the total amount of charged monomers. Further characteristics of the process and of the isoprene/pentadiene copolymer obtained are set down in Table 1.

[0385] FIG. 34 shows the FT_IR spectrum of the isoprene/pentadiene stereoregular copolymer obtained.

[0386] FIG. 35 shows the .sup.1H and .sup.13C NMR spectra.

Example 14

Synthesis of Pentadiene/Isoprene/Butadiene Stereoregular Terpolymer with an Alternating 1,4-Cis/3,4 Structure for the Polyisoprene Block and a Syndiotactic 1,2 Structure for the Polypentadiene and Polybutadiene Blocks (Invention)

[0387] 1 ml of E-1,3-pentadiene equal to 0.68 g was introduced into a 50 ml test-tube. 20 ml of heptane was subsequently added and the temperature of the solution thus obtained was taken to 25 C. Methylaluminoxane (MAO) in toluene solution (1.89 ml; 310.sup.3 moles, equal to about 0.174 g) was then added and, subsequently, the solution prepared as described in example 1a (0.3 ml; 310.sup.5 moles of Co) (molar ratio Al/Co=100). The whole mixture was kept under magnetic stirring at 25 C. for 120 minutes, then 3 ml of isoprene (2.04 g) dissolved in heptane (5 ml) was added. The polymerization was left to proceed for a further 150 minutes, then 1 ml of butadiene (0.7 g) dissolved in heptane (9 ml) was added and polymerization continued, still under stirring at room temperature, for a further 60 minutes. The polymerization was quenched by adding 2 ml of methanol. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of antioxidant Irganox 1076 (Ciba) obtaining 3.34 g of pentadiene-isoprene-butadiene terpolymer, with a conversion equal to 98.5% relative to the total amount of charged monomers. Further characteristics of the process and of the pentadiene/isoprene/butadiene terpolymer obtained are set down in Table 1.

[0388] FIG. 36 shows the FT-IR spectrum of the pentadiene/isoprene/butadiene stereoregular terpolymer obtained.

[0389] FIG. 37 shows the .sup.1H and .sup.13C NMR spectra.

Example 15

Synthesis of Pentadiene/Isoprene/Butadiene Stereoregular Terpolymer with an Alternating 1,4-Cis/3,4 Structure for the Polyisoprene Block and a Syndiotactic 1,2 Structure for the Polypentadiene and Polybutadiene Blocks (Invention)

[0390] 0.5 ml of E-1,3-pentadiene equal to 0.34 g was introduced into a 50 ml test-tube. 20 ml of heptane was subsequently added and the temperature of the solution thus obtained was taken to 25 C. Methylaluminoxane (MAO) in toluene solution (1.89 ml; 310.sup.3 moles, equal to about 0.174 g) was then added and, subsequently, the solution prepared as described in example 1a (0.3 ml; 310.sup.5 moles of Co) (molar ratio Al/Co=100). The whole mixture was kept under magnetic stirring at 25 C., for 120 minutes, then 3 ml of isoprene (2.04 g) dissolved in heptane (5 ml) was added. The polymerization was left to proceed for a further 150 minutes, then 0.5 ml of butadiene (0.35 g) dissolved in heptane (9 ml) was added and polymerization continued, still under stirring and at room temperature, for a further 60 minutes. The polymerization was quenched by adding 2 ml of methanol. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of antioxidant Irganox 1076 (Ciba) obtaining 2.69 g of pentadiene/isoprene/butadiene terpolymer, with a conversion equal to 95% relative to the total amount of charged monomers. Further characteristics of the process and of the pentadiene/isoprene/butadiene terpolymer obtained are set down in Table 1.

[0391] FIG. 38 shows the FT_IR spectrum of the pentadiene-isoprene-butadiene stereoregular terpolymer obtained.

[0392] FIG. 39 shows the .sup.1H and .sup.13C NMR spectra.

Example 16

Synthesis of Butadiene/Isoprene/Butadiene Stereoregular Terpolymer with an Alternating 1,4-Cis/3,4 Structure for the Polyisoprene Block and a Syndiotactic 1,2 Structure for the Polybutadiene Blocks (Invention)

[0393] 1.5 ml of butadiene equal to 1.05 g was condensed at a low temperature (20 C.) in a 50 ml test-tube. 25 ml of heptane was subsequently added and the temperature of the solution thus obtained was taken to 25 C. Methylaluminoxane (MAO) in toluene solution (1.26 ml; 210.sup.3 moles, equal to about 0.116 g) was then added and, subsequently, the solution prepared as in example 1c (0.2 ml; 210.sup.5 moles of Co) (molar ratio Al/Co=100). The whole mixture was kept under magnetic stirring at 25 C. for 18 minutes, then 5 ml di isoprene (3.4 g) was added. The polymerization was left to proceed for a further 360 minutes, then 1 ml of butadiene (0.7 gr) in toluene solution (5 ml) was added, and the polymerization was left to proceed for a further 15 minutes. The polymerization was quenched by adding 2 ml of methanol. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of antioxidant Irganox 1076 (Ciba) obtaining 4.89 g of butadiene/isoprene/butadiene terpolymer, with a conversion equal to 94.9% relative to the total amount of charged monomers. Further characteristics of the process and of the butadiene/isoprene/butadiene terpolymer obtained are set down in Table 1.

[0394] FIG. 40 shows the FT_IR spectrum of the butadiene/isoprene/butadiene stereoregular terpolymer obtained.

[0395] FIG. 41 shows the .sup.1H and .sup.13C NMR spectra.

[0396] FIG. 42 shows the DSC curve.

Example 17

Synthesis of Butadiene/Isoprene/Butadiene Stereoregular Terpolymer with an Alternating 1,4-Cis/3,4 Structure for the Polyisoprene Block and a Syndiotactic 1,2 Structure for the Polybutadiene Blocks (Invention)

[0397] 1.0 ml of butadiene equal to 0.7 g was condensed at a low temperature (30 C.) in a 50 ml test-tube. 25 ml of heptane was subsequently added and the temperature of the solution was taken to the temperature of 25 C. Methylaluminoxane (MAO) in toluene solution (1.26 ml; 210.sup.3 moles, equal to about 0.116 g) was then added and, subsequently, the solution prepared as in example 1b (0.2 ml; 210.sup.5 moles of Co) (molar ratio Al/Co=100). The whole mixture was kept under magnetic stirring at 25 C., for 15 minutes; 8 ml of isoprene (5.44 g) was then added. The polymerization was left to proceed for a further 300 minutes, then a further 2 ml of butadiene (1.4 gr) was added and the polymerization was continued for a further 30 minutes. The polymerization was quenched by adding 2 ml of methanol. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of antioxidant Irganox 1076 (Ciba) obtaining 7.18 g of butadiene/isoprene/butadiene terpolymer, with a conversion equal to 95.7% relative to the total amount of charged monomers. Further characteristics of the process and of the butadiene/isoprene/butadiene terpolymer obtained are set down in Table 1.

[0398] FIG. 43 shows the FT_IR spectrum of the butadiene/isoprene/butadiene stereoregular terpolymer obtained.

[0399] FIG. 44 shows the .sup.1H and .sup.13C NMR spectra.

[0400] FIG. 45 shows the DSC curve.

Example 18

[0401] 0.5 grams of natural rubber and 1.5 grams of the isoprene/butadiene stereoregular copolymer according to Example 6 of the present invention are introduced into a 250 ml flask and dissolved in boiling toluene. Once the solubilization is complete, the polymers are re-precipitated in a large excess of methanol, filtered and then dried under vacuum at room temperature for a whole night up to constant weight. The polymer thus obtained is used as is for AFM analysis.

[0402] FIG. 47 shows the Atomic Force Microscopy (AFM) images of the above mixture.

[0403] Discussion of Differences of the Copolymers of the Invention from Copolymers of the Prior Art

[0404] Comparison between the isoprene/butadiene stereoregular copolymer according to Example 6 of the present invention and the butadiene-isoprene block copolymer according to Example 18 of US 2020/0109229 A1.

[0405] Both these two copolymers have a molar content of isoprene: butadiene of about 70:30. FIG. 46 (a) shows the .sup.13C NMR spectrum (olefinic region) of the copolymer of Example 6 of the present invention, which is the same spectrum as that of FIG. 18b but with indication of the characteristic signals relating to the olefinic carbon atoms of 1,4-cis/3,4 polyisoprene (PI) and of syndiotactic 1,2 polybutadiene (PB).

[0406] FIG. 46 (b) shows the .sup.13C NMR spectrum (olefinic region) of the copolymer of Example 18 of US 2020/0109229 A1, which is the same as the top spectrum of FIG. 26 of US 2020/0109229 A1, but with indication of the characteristic signals relating to the olefinic carbon atoms of 3,4 polyisoprene (PI) and syndiotactic 1,2 polybutadiene (PB).

[0407] As discussed in the section concerning the prior art, US 2020/0109229 A1 discloses copolymers obtained by iron catalysis in which the polybutadiene block consists of crystalline polybutadiene (the hard block) with an essentially 1,2 structure (1,2 content around 70-80%, the remaining units having a cis-1,4 structure), and in which the amorphous polyisoprene block is made up of polyisoprene (the soft block) with a predominantly 3,4 structure (around 70%, the remaining units having a cis-1,4 structure).

[0408] It is to be noted that while in the copolymer of US 2020/0109229 A1 the amorphous polyisoprene block has a predominantly 3,4 structure, in the copolymer of the present invention the amorphous polyisoprene block has a perfectly alternating cis-1,4-alt-3,4 structure.

[0409] The different structures of the polyisoprene blocks of US 2020/0109229 A1 and of the present invention appear evident from the comparison of the .sup.13C NMR spectra of the olefinic regions of the two copolymers.

[0410] In the spectrum of FIG. 46 (b) the signals at 110 ppm and 145.33 ppmcorresponding to the C1 and C2 olefinic carbons of a 3,4 isoprene unit, respectivelyare clearly indicative of 3,4 units involved in long 3,4 unit sequences, that is a polyisoprene block with a predominant 3,4 structure.

[0411] In the spectrum of FIG. 46 (a), the signals at 108.96 and 146.10 ppm again correspond to the C1 and C2 olefinic carbons of a 3,4isoprene unit, but involved in a perfectly alternating cis-1,4/3,4 structure. Such an alternating structure is confirmed by the presence of signals at 131.90 and 124.68 ppm, corresponding to the C2 and C3 olefinic carbons of a cis-1,4 isoprene unit involved in perfectly alternating cis-1,4-alt-3,4 isoprene unit sequences.

[0412] The features discussed above show the structural differences between the copolymers of the prior art, obtained by catalytic systems based on iron compounds, and the copolymers of the invention, obtained by catalytic systems based on cobalt compounds.

[0413] One of the effects of the structural differences discussed above is that the block copolymers of the invention show a good compatibility with natural rubber, as shown by the AFM images of FIG. 47, likely due to the high content of isoprene units with a cis-1,4 structure.

TABLE-US-00001 TABLE 1 Copolymerization of dienes with CoCl.sub.2/Phosphine/MAO .sup.a) Polymerization Composition Characterization polymer Conc Pentadiene Isoprene Butadiene Time Yield Conv. polymer (molar %) (rr).sup.(b) (rr).sup.(c) T.sub.m.sup.(d) T.sub.c.sup.(e) T.sub.g.sup.(f) M.sub.w M.sub.w/ Example (mol) Phosphine (ml) (mL) (mL) Feed P/I/B (min) (g) (%) Pentadiene Isoprene Butadiene (%) (%) ( C.) ( C.) ( C.) (g/mol) M.sub.n 2 30 iso-propyl- 2 100/0/0 90 1.36 100 100 90 132 180000 2.3 diphenylphosphine 3 30 iso-propyl- 5 0/100/0 180 3.4 100 100 18 89100 2.3 diphenylphosphine 4 10 iso-propyl- 2 0/0/100 105 1.4 100 100 80.5 125 240000 1.8 diphenylphosphine 5 30 tri- 5 0.5 0/88.5/11.5 150 + 60 3.61 97 84.6 15.4 62.5 79.8 36.2 19 198000 2.1 phenylphosphine 6 30 tri- 5 1.5 0/72.1/27.9 150 + 60 4.36 96.8 71.4 28.6 66.0 80.3 39.5 18 211300 2.0 phenylphosphine 7 30 Cyclohexyl- 5 2.5 0/61.0/39.0 150 + 60 5.10 99.1 59.6 40.4 70.0 106.5 56.3 18 291500 2.3 diphenylphosphine 8 20 iso-propyl- 5 1.5 0/72.1/29.9 7 + 120 4.27 95.1 69.3 30.7 76.4 123.6 99.8 19 288000 1.8 diphenylphosphine 9 20 iso-propyl- 8 2.0 0/75.5/24.5 18 + 360 6.6 97.5 76.1 23.9 74.4 128.3 103.7 18 307200 2.2 diphenylphosphine 10 20 tert-butyl 8 1.0 0/86/14 45 + 300 5.9 96.7 83.5 16.5 82.5 122.7 99.3 17 211100 1.9 diphenylphosphine 11 10 iso-propyl- 5 4.0 0/50.9/49.1 200 + 300 6.0 96.8 50 50 73.7 110.5 77.7 18 315200 1.7 diphenylphosphine 12 30 iso-propyl- 1 4 20/80/0 150 + 120 3.33 97.9 18.5 81.5 84.7 119.0 19 220000 2.1 diphenylphosphine 13 30 iso-propyl- 2 3 40/60/0 150 + 120 3.22 97.7 39.1 60.9 87.8 124.6 18 21200 2.2 diphenylphosphine 14 30 iso-propyl- 1 3 1 18.9/56.6/24.5 120 + 150 + 60 3.34 98.5 19.2 57 23.8 78.5 85.0 ~120 19 306000 2.3 diphenylphosphine 15 30 iso-propyl- 0.5 3 0.5 12/72.3/15.7 120 + 150 + 60 2.69 95 12.5 72.6 14.9 75.1 83.8 ~118 18 292500 2.2 diphenylphosphine 16 20 Cyclohexyl- 5 2.5 0/61/39 18 + 360 + 15 4.89 94.9 61.4 38.7 68.6 105.5 57.9 18 245000 2.3 diphenylphosphine 17 20 tert-butyl 8 3 0/67.3/32.7 45 + 300 + 30 7.18 95.7 71 29 81.0 119.5 18 236300 2.2 diphenylphosphine [0414] (a): polymerization conditions: in examples 5-7 first isoprene and then butadiene were added; in examples 8-11, first butadiene and then isoprene; in examples 12,13 first pentadiene and then isoprene; in examples 14,15 first pentadiene, then isoprene and, finally, butadiene; in examples 16,17 first butadiene, then isoprene and, finally, butadiene again; polymerization temperature 25 C. [0415] (b): content of syndiotactic triads [(rr) %] in the polybutadiene block with a syndiotactic 1,2 structure determined by means of .sup.13C-NMR analysis; [0416] (c): content of syndiotactic triads [(rr) %] in the polypentadiene block with a syndiotactic 1,2 structure determined by means of .sup.13C-NMR melting point analysis; [0417] (d): melting point; [0418] (e): crystallization temperature; [0419] (f): glass transition temperature.