Description

Compositions of ionisable organosiloxane polymers

Cross reference to related applications

[0001] This application claims priority to Indian provisional patent application No.

201821030135 filed on August 10, 2018 and to European patent application No. 18208770.0 filed on November 28, 2018, the whole content of each of these applications being incorporated herein by reference for all purposes.

Technical Field

[0002] The present invention relates to organosiloxane polymers compositions, in particular to compositions comprising ionisable organosiloxane polymers.

Background Art

[0003] Elastomeric compositions based on supramolecular polymer assemblies are known. Supramolecular polymer assemblies consist of polymeric units held together via non-covalent interactions, for example ionic interactions.

[0004] There are some examples in the prior art of associations between

polymers that result in supramolecular polymers assemblies.

[0005] US 5498457 (HITACHI) discloses a lubricanting layer comprising ionically interbonded fluoropolyethers with acidic and basic terminal groups, in particular comprising a fluoropolyether lubricant having at least two acidic terminal groups in each molecule and a fluoropolyether lubricant having at least two basic terminal groups in each molecule. This document teaches that these two fluoropolyether lubricants form a stable network structure by an appropriate combination of the lubricant having the acidic groups and the one having the basic groups.

[0006] WO 2013/017470 (SOLVAY SPECIALTY POLYMERS ITALY SPA)

discloses compositions comprising two ionisable fluoropolymers at an ionic ratio of 0.9-1.1. Each fluoropolymer comprises recurring fluorinated blocks and recurring blocks comprising at least one ionisable anionic or cationic group, wherein at least one ionizable recurring block is comprised between two fluorinated blocks. This document teaches that such compositions form elastomeric materials showing, in certain instances, a self-repairing behaviour.

[0007] Similar compositions are disclosed in WO 2014/090646 (SOLVAY

SPECIALTY POLYMERS ITALY SPA). This document teaches that they are stable even after addition of a cross-linking agent and can be used for the manufacture of polymeric materials endowed with high chemical stability, improved mechanical properties and possibly self-healing properties.

[0008] WO 2018/078001 (SOLVAY SPECIALTY POLYMERS ITALY SPA)

discloses compositions including at least a first polymer comprising a polymer chain consisting of a plurality of non-ionisable recurring units (such as a (per)fluorinated polyoxyalkylene chain, a polyalkylsiloxane chain, a polyoxyalkylene chain, a polycarbonate chain and a polyester chains) and having two chain ends, each end comprising at least one ionisable acid group, and at least a second polymer - whose chain is equal or different from that of the first polymer - having two chain ends, each end comprising at least one ionisable amino group.

[0009] The need is felt to provide novel compositions comprising polymers having ionisable anionic and cationic groups able to interact or form

supramolecular structures, which have improved elastomeric properties with respect to the compositions known in the art.

Summary of invention

[0010] The present invention relates to a polymer composition comprising:

a) at least one polymer [polymer (P1)] comprising a polyalkylsiloxane

chain [chain (R _s )], said chain R _s consisting of a plurality of recurring units [units (Us)] of formula:

(Us) Ra _s

i

- OS i -

Rb _s

wherein Ra _s and Rb _s are equal to or different from one another and independently selected from hydrogen, straight or branched (halo)alkyl and aryl, with the proviso that at least one of Ra _s and Rb _s is not hydrogen, said polymer (P1) having two chain ends, each end comprising at least two ionisable acid groups;

b) at least one polymer [polymer (P2)] comprising a chain (R _s ) _, as above detailed, said chain (R _s ) being equal to or different from that of polymer (P1) and said polymer (P2) having two chain ends, each end comprising at least two ionisable amino groups.

[0011] The Applicant has surprisingly found that by using polymer (P1) and

polymer (P2) as defined above, which comprise a polyalkylsiloxane chain and at least two ionisable acid and amino groups at respective chain ends, it is possible to obtain ionically interconnected polymer networks with a higher elasticity than those comprising a chain of different nature, i.e. a chain other than polyalkylsiloxane chain. Said ionically interconnected polymer networks are also provided with a higher elasticity than those having two acid groups but only one amino group at respective chain ends.

Detailed Description of the Invention

[0012] In the present description, unless otherwise indicated, the following terms are to be meant as follows.

[0013] A“trivalent hydrocarbon group” is a trivalent radical derived from a

hydrocarbon by removal of three atoms of hydrogen from carbon atoms; a trivalent hydrocarbon group thus comprises three ends, each end being able to form a linkage with another chemical group.

[0014] An“alicyclic group” is an aliphatic cyclic group consisting of one or more all-carbon rings which may be either saturated or unsaturated. [0015] The adjective“aromatic” denotes any mono- or polynuclear cyclic group (or moiety) having a number of p electrons equal to 4n+2, wherein n is 0 or any positive integer; an aromatic group (or moiety) can be an aryl or an arylene group (or moiety).

[0016] An“aromatic group” consists of one core composed of one benzenic ring or of a plurality of benzenic rings fused together by sharing two or more neighboring ring carbon atoms. Non limitative examples are benzene, naphthalene, anthracene, phenanthrene, tetracene, triphenylene, pyrene, perylene.

[0017] Alicyclic and aromatic groups can be substituted with one or more straight or branched alkyl or alkoxy groups and/or halogen atoms and/or can comprise one or more heteroatoms, like nitrogen, oxygen and sulfur, in the ring.

[0018] The use of parentheses“(...)” before and after the names of compounds, symbols or numbers identifying formulae or parts of formulae like, for example,“polymer (P1)”,“chain (R)”, etc..., has the mere purpose of better distinguishing those names, symbols or numbers from the remaining text; thus, said parentheses could also be omitted.

[0019] The expression "average functionality (F)" denotes the average number of functional groups per polymer molecule and can be calculated according to methods known in the art.

[0020] The“storage modulus (G’)” is the measurement of the stored energy, which represents the elastic portion of the composition, and the“loss modulus (G”)” is the measurement of the energy dissipated as heat, which represents the viscous portion of the composition.

[0021] When ranges are indicated, range ends are included.

[0022] The expressions“ionisable amino groups” and“ionisable acid groups” identify amino or acid groups able to form ionic groups, namely cationic and anionic groups respectively. In greater detail, an ionisable amino group identifies a primary, secondary or tertiary amino group, while an ionisable acid group identifies an acid group comprising at least one hydroxyl function in its protonated form, i.e. a protic acid group. POLYMER (P1 )

[0023] Polymer (P1) can be represented with formula (P1) here below:

(P1 ) E1 -Rs-E1’

wherein Rs is a polyalkylsiloxane chain [chain (R _s )], as detailed above, and E1 and E1’, equal to or different from one another, are end groups each comprising at least two ionisable acid groups. Preferably, E1 and E1’ do not comprise ionisable amino groups.

[0024] Polyalkylsiloxane chain (Rs)

[0025] As said, chain (Rs) consists of a plurality of recurring units [units (Us)], as detailed above.

[0026] In a preferred embodiment, in formula (U _s ), both Ra _s and Rb _s are methyl, i.e. chain (Rs) is a polydimethylsiloxane chain [chain (Rs-I)], which consists of a plurality of recurring units of formula (Us-i) here below:

(Us-i): -OSi(CH ₃ )2-.

[0027] Minor amounts (e.g. <1 %(wt), based on the weight of chain (Rs-I)) of

spurious units, defects or recurring unit impurities may be comprised in chain (Rs-I) without this affecting chemical properties of this chain.

[0028] Chain (Rs) has a number average molecular weight (M _n ) preferably

ranging from 500 to 10,000, more preferably from 500 to 5,000.

[0029] Groups El and EV

[0030] End groups E1 and E1’ typically comprise at least two ionisable acid

groups selected among carboxylic acid groups, phosphonic acid groups and sulfonic acid groups. Each of said ionisable acid groups is able to form an anionic group via acid/base reaction with one of the at least two ionisable amino groups at one end of polymer (P2).

[0031] Preferably, groups E1 and E1’ are equal to one another.

[0032] Preferably, groups E1 and E1’ comply with formula (E1-A) here below:

(E1-A) -B1-(EA) ₂

wherein:

B1 is a trivalent hydrocarbon group preferably comprising from 1 to 20 carbon atoms and possibly comprising one or more than one heteroatom, said heteroatom(s) being preferably selected among N, S and O; and EA represents a -COOH, a -P(0)(0REA)2 or a -S(0) ₂ 0H group, wherein one of REA is hydrogen and the other one is hydrogen or straight or branched alkyl, preferably Ci-C ₄ alkyl. In one preferred embodiment, EA is a -COOH group.

[0033] Preferably, B1 comprises one or more of the groups selected from: -0-, - S-, -0C(0)0-, -OC(0)NH-, -NH-C(O)-, OC(0)S-, -SC(0)S-, -NHC(0)NH-, -NH-C(=S) and -NHC(S)NH-.

[0034] Preferably, B1 comprises one or more than one cyclic hydrocarbon group, which may be alicyclic group(s), aromatic group(s), heterocyclic group(s) comprising one or more than one heteroatom, and heteroaromatic group(s) comprising one or more than one heteroatom, the heteroatom(s) being preferably selected from N, S and O. Each of said cyclic

hydrocarbon groups may comprise one or more substituents. In case B1 comprises more than one cyclic group, i.e. at least two cyclic gropus, said cyclic groups may be condensed or may be connected through a bond or through any (hydro)carbon divalent group optionally comprising one or more than one heteroatom, said heteroatom(s) being preferably selected from N, S and O.

[0035] According to a preferred embodiment, polymer P1 complies with the

following formula (P1-A) here below:

(P1 -A) R _s -[(CH ₂ )ns*NHC(0)-RBi-(C00H)2]2

wherein ns ^* is 0 or a positive number equal to or higher than 1 , preferably ranging from 1 to 10, and R _BI is a C1-C10 straight or branched aliphatic group, a C ₄ -C6 alicyclic group or heterocyclic group, a C5-C6 aromatic group or heteroaromatic group. Rs is advantageously a chain of formula Si(CH3)20[Si(CH ₃ )20]nsSi(CH ₃ )2 [chain (Rs-I)], with ns being a positive number selected in such a way that the number average molecular weight (Mn) of the [Si(CH ₃ ) ₂ 0]ns chain preferably ranges from 500 to 10,000, more preferably from 500 to 5,000, as defined above.

[0036] Preferably, R _BI is an aromatic group. More preferably, R _BI is a C6 aromatic group. According to different embodiments, each -COOH group may be in ortho, meta, para positions with respect to -NHC(O)-. According to different embodiments, each -COOH group may be in ortho, meta, para positions with respect to each other.

[0037] A preferred example of polymer (P1-A) is one complying with formula (P1- Aa) here below:

(P1-Aa)

POLYMER

[0038] Polymer (P2) can be represented with formula (P2) here below:

(P2) E2-Rs-E2’

wherein Rs is a polymer chain as defined above, and E2 and E2’, equal to or different from one another, are end groups each comprising at least two ionisable amino groups. Preferably, E2 and E2’ do not comprise ionisable acid groups.

[0039] Chain (Rs) of polymer (P2) can be equal to or different from the chain (Rs) of polymer (P1).

[0040] Groups E2 and E2’

[0041] End groups E2 and E2’ typically comprise at least two ionisable amino groups selected among primary, secondary or tertiary amino groups.

“Ionisable primary, secondary or tertiary amino group” means that the amino group is in its free form, so that it is capable to form a cationic group via acid/base reaction with one of the at least two ionisable acid groups at one end of the polymer (P1).

[0042] Preferably, groups E2 and E2’ are equal to one another.

[0043] Preferably, groups E2 and E2’ comply with formula (E2-A) here below:

(E2-A) -B2-(N(Rp ₂ ) ₂ )2

wherein:

B2 is a trivalent hydrocarbon group preferably comprising from 1 to 20 carbon atoms and possibly comprising one or more than one heteroatom, said heteroatom(s) being preferably selected among N, S and O; and each of R _P 2, equal to or different from each other at each occurrence, is hydrogen or straight or branched alkyl, preferably Ci-C ₄ alkyl.

[0044] Preferably, B2 comprises one or more than one group selected from the following: -0-, -S-, -0C(0)0-, -0C(0)NH-, -NH-C(O)-, OC(0)S-, -SC(0)S-, -NHC(0)NH-, -NHC(S)NH-, -N(Rp2 _* )- wherein Rp2 _* represents hydrogen or straight or branched alkyl, preferably Ci-C ₄ alkyl, more preferably methyl.

[0045] Preferably, B2 comprises one or more than one cyclic hydrocarbon group, which may be alicyclic group(s), aromatic group(s), heterocyclic group(s) comprising one or more than one heteroatom, and heteroaromatic group(s) comprising one or more than one heteroatom, the heteroatom(s) being preferably selected from N, S and O. Each of said cyclic

hydrocarbon groups may comprise one or more substituents. In case B2 comprises more than one cyclic group, i.e. at least two cyclic gropus, said cyclic groups may be condensed or may be connected through a bond or through any (hydro)carobn divalent group possibly comprising one or more than one heteroatom, said heteroatom(s) being preferably selected from N, S and O.

[0046] According to a preferred embodiment, polymer P2 complies with the

following formula (P2-A) here below:

(P2-A) Rs-[(CH ₂ )ns*NH-RB2-(NH ₂ )2]2

wherein ns ^* is 0 or a positive number equal to or higher than 1 , preferably ranging from 1 to 10, and R _B 2 is a C1-C10 straight or branched aliphatic group, a C ₄ -C6 alicyclic group or heterocyclic group, a C5-C6 aromatic group or heteroaromatic group. Rs is advantageously a chain of formula Si(CH3)20[Si(CH ₃ )20]nsSi(CH ₃ )2 [chain (Rs-I)], with ns being a positive number selected in such a way that the number average molecular weight (Mn) of the [Si(CH ₃ ) ₂ 0]ns chain preferably ranges from 500 to 10,000, more preferably from 500 to 5,000, as defined above.

[0047] Preferably, R _B 2 is an aromatic group. More preferably, R _B 2 is a

heteroaromatic group. Even more preferably, R _B 2 IS a C6 heteroaromatic group. [0048] A preferred example of polymer (P2-A) is one complying with formula (P2- Aa) here below:

COMPOSITION (C) AND ITS MANUFACTURE

[0049] Composition (C) can be prepared by mixing polymer (P1) and polymer (P2) according to conventional mixing techniques at an equivalent ratio between polymer (P1) and polymer (P2) ranging from 1.1 to 0.9. Mixing can be carried out with or without solvents, using appropriate mixing equipment. For the avoidance of doubt, the ratio between the equivalents of polymer (P1) and the equivalents of polymer (P2) is referred to the acid/base reaction between the at least two ionisable amino groups in each end group of polymer (P1) and the at least two ionisable acid groups in each end of polymer (P2).

[0050] One or more polymers (P1) can be used in the manufacture of

composition (C).“More polymers” means that polymers (P1) can be used which differ from one another in the kind of recurring units (Us) of the chain (Rs), in the kind of end groups (E1) and (E1’) or both.

[0051] One or more polymers (P2) can also be used in the manufacture of

composition (C).’’More polymers” means that polymers (P2) can be used which differ from one another in the kind of recurring units (Us) of the chain (Rs), in the kind of end groups (E2) and (E2’) or both.

[0052] According to a preferred embodiment, one polymer (P1) and one polymer (P2) are used in the manufacture of composition (C); the chain (Rs) of polymer (P1) can be equal to or different from the chain (Rs) of polymer (P2).

[0053] According to one embodiment, chain (Rs) in either (P1) or (P2) is a chain of formula (Rs-I) as defined above.

[0054] Convenient compositions (C) comprise a polymer (P1) and a polymer (P2) wherein, in both polymers, chains (Rs) are chains of formula (Rs-I). [0055] Composition (C) may further comprise one or more organic polar protic or aprotic solvents. Non limiting examples of solvents are alcohols, ketones, acetates, dimethylacetamide (DMA), hydrofluoroethers, toluene, bis- trifluorodimethylbeneze, ethers. Preferred organic solvents are ketones, like methylethylketone (MEK), acetates, like ethylacetate and butyl acetate, and ethers, like ter-Buthylmethylether.

[0056] When present, said one or more than one organic solvent is comprised in compositions (C) in an amount ranging from 1 % to 99.9%(wt) with respect to the overall weight of the composition.

[0057] Without being bound to theory, it is believed that, when a polymer (P1) and a polymer (P2) are mixed in the above equivalent ratio, at least two ionisable acid groups at each end of polymer (P1) undergo acid/base reaction with at least two ionisable amino group at each end of polymer (P2). It will thus be understood by a person skilled in the art that any optional ingredient in composition (C) will have to be selected in such a way and amount that it does salify the ionisable acid and amino groups of polymers (P1) and (P2).

[0058] Should the disclosure of any patents, patent applications and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

[0059] The invention is described in greater detail in the following experimental section by means of non-limiting examples.

Experimental section

[0060] Materials

[0061] Trimellitic anhydride, 2-chloro-4,6-diamino-1 ,3,5 triazine, potassium

hydrogen carbonate, methanesulfonyl chloride, 1 ,4-dioxane, 2-propanol (IPA), t-butylmethyl ether (TBME), toluene, dichloromethane, acetone were purchased from Aldrich® and used as received.

[0062] Polymers (P3) of formula:

NH ₂ -(CH2)ns-RS-(CH ₂ )ns-NH2 with Rs being a poly(dimethylsiloxane) chain, ns = 3 and Mn = 900

[herein after (P3A)], Mn = 3000 [herein after (P3B)], Mn = 5000

[herein after (P3C)] were obtained from Gelest®.

[0063] Polymer (PR1 ) of formula:

HO-(CH ₂ )ns-Rs-(CH ₂ )ns _* -OH

with Rs being a poly(dimethylsiloxane) chain, ns = 5, ns ^* = 5 and Mn = 5600 was obtained from Aldrich®.

[0064] Polymer (P4) of formula:

with Rs being a poly(dimethylsiloxane) chain, ns = 4, ns ^* = 3 and Mn = 4682 was obtained from Aldrich®.

[0065] Poly(propyleneglycol) (Mn 2000) [herein after (PPG-diol)] was purchased from Aldrich ^® and was used as received.

[0066] Poly(propyleneglycol)-bis(2-aminopropylether) (Mn 2000 [herein after (PPG-diamine)] was purchased from Aldrich® and was used as received. It is a low viscous liquid characterized by a T _g of -70°C, it contains two amine groups per molecule, and complies with formula:

with n being an integer so as to provide for the Mn as detailed above.

[0067] Methods

[0068] Preparation of compositions

[0069] All compositions were prepared by mixing polymer (P1) and polymer (P2) at an equivalent ratio of 1 [i.e. nr acidic groups of polymer (P1) = nr basic groups of polymer (P2)].

[0070] In a typical procedure, the polymer (P1) and polymer (P2) were individually dissolved in a suitable solvent (1-99 wt% for instance in tert-Butyl methyl ether or ethyl acetate or dichloromethane) and then mixed together in a reactor equipped with a mechanical stirrer at room temperature (30 °C). The mixture was kept at room temperature (25 °C) for 12 hours, after that the solvent was removed at 70 °C under reduced pressure (0.001 torr).

[0071] Viscosities and moduli of the compositions were measured one week after their preparation.

[0072] Viscosity

[0073] Rheological measurements were carried out with a rotational rheometer “ARES G2 from TA Instruments”

[0074] Test geometry: 25 mm circular parallel plate

[0075] Test mode 1 : Frequency sweep from 1 rad/sec to 500 rad/sec at constant temperature (30 °C).

[0076] Test mode 2: Temperature sweep from 30 °C to melting/softening of

composite at constant frequency (10 rad/sec).

[0077] Temperature and frequency dependence of storage modulus (G’), loss modulus (G”) and viscosity were estimated for the compositions (C) at a frequency of 10rad/sec.

[0078] ¹³ C and ¹ H NMR

[0079] NMR analyses were performed on a Bruker Avance™ 400 MHz

spectrometer with a 5 mm probe and the obtained spectra were processed using Bruker’s TopSpin™ software (3.2 ver.).

[0080] The polymer structures were determined by ¹ H or ¹³ C NMR analyses. The number average molecular weight (M _n ) of the polymers (P1) and (P2) were estimated by polymer and group analysis (using ¹ H NMR spectra).

[0081] Synthesis examples

[0082] Example 1 - Synthesis of a polymer (P1 A) of formula:

wherein Rs is a poly(dimethylsiloxane) chain, Mn 1520 [herein after (P1A Ex1)]. [0083] A glass reactor was charged with polymer P3A (100 g, 111 mmol, Mn 900) and dried under vacuum for two hours under mechanical stirring at 70 °C.

1 ,4-dioxane (100 ml) and trimellitic anhydride (53.458 g, 278 mmol) were added to the reactor and stirred at 100 °C for 12 hours. The reaction completion was monitored by ¹ H-NMR. The NMR analyses confirmed the obtainment of title product, with purity higher than 99% and the estimated molecular weight (Mn) of 1520.

[0084] Example 2 - Synthesis of a polymer (P1 B) of formula:

wherein Rs is a poly(dimethylsiloxane) chain, Mn 3444 [herein after (P1 B- Ex2)].

[0085] A glass reactor was charged with polymer P3B (100 g, 33.33 mmol, Mn 3000) and dried under vacuum for two hours under mechanical stirring at 70 °C. 1 ,4-dioxane (100 ml) and trimellitic anhydride (15.95 g, 83 mmol) were added to the reactor and stirred at 100 °C for 18 hours. The reaction completion was monitored by ¹ H-NMR. The NMR analyses confirmed the obtainment of title product, with purity higher than 99%.

[0086] Example 3 - Synthesis of a polymer (P1C) of formula:

wherein Rs is a poly(dimethylsiloxane) chain, Mn 6256 [herein after (P1C- Ex3)].

[0087] A glass reactor was charged with polymer P3C (100 g, 20 mmol, Mn 5000) and dried under vacuum for two hours under mechanical stirring at 70 °C. 1 ,4-dioxane (100 ml) and trimellitic anhydride (9.606 g, 50 mmol) were added to the reactor and stirred at 100 °C for 24 hours. The reaction completion was monitored by ¹ H-NMR. The NMR analyses confirmed the obtainment of title product, with purity higher than 99%.

[0088] Example 4- Synthesis of a polymer (P2A) of formula:

wherein Rs is a poly(dimethylsiloxane) chain, Mn 1206 [herein after (P2A- Ex4)].

[0089] A glass reactor was charged with 2-chloro-4,6-diamino-1 ,3,5-triazine

(48.46 g, 333 mmol), KHCO3 (33.338 g, 333 mmol), 2-propanol (300 ml_) and water (150 ml_) and the so obtained reaction mixture was

warmed up to 70°C. P3A (100 g, 1 1 1 mmol, Mn 900) was added to the reaction mixture and stirred at 90 °C. The completion of the reaction was monitored by ¹ H-NMR. The solvent was evaporated under reduced pressure and the polymer was purified by selective impurity precipitation in ethyl acetate solvent. All analyses confirmed the obtainment of the title product, with purity higher than 99%.

[0090] Example 5 - Synthesis of a polymer (P2B) of formula:

wherein Rs is a poly(dimethylsiloxane) chain, Mn 3278 [herein after (P2B- Ex5)].

[0091] A glass reactor was charged with 2-chloro-4,6-diamino-1 ,3,5-triazine

(14.553 g, 99.99 mmol), KHC03 (10.033 g, 99.99 mmol), 2-propanol (300 ml_) and water (150 ml_) and the so obtained reaction mixture was warmed up to 70°C. P3B (100 g, 33.33 mmol, Mn 3000) was added to the reaction mixture and stirred at 90 °C. The completion of the reaction was monitored by 1 H-NMR. The solvent was evaporated under reduced pressure and the polymer was purified by selective impurity precipitation in ethyl acetate solvent. All analyses confirmed the obtainment of the title product, with purity higher than 99%. [0092] Example 6 - Synthesis of a polymer (P2C) of formula:

wherein Rs is a poly(dimethylsiloxane) chain, Mn 5700 [herein after (P2C- Ex6)].

[0093] A glass reactor was charged with 2-chloro-4,6-diamino-1 ,3,5-triazine

(8.733 g, 60 mmol), KHCO3 (6.006 g, 60 mmol), 2-propanol (150 ml_) and water (20 ml_). P3C (100 g, 20 mmol, Mn 5000) was added to the reaction mixture and stirred at 90 °C. The completion of the reaction was monitored by ¹ H-NMR. The solvent was evaporated under reduced pressure and the polymer was purified by selective impurity precipitation in ethyl acetate solvent. All analyses confirmed the obtainment of the title product, with purity higher than 99%.

[0094] Example 7 - Synthesis of a polymer (P5) of formula:

NH ₂ -(CH ₂ ) ₂ -NH-(CH ₂ ) ₃ -R _S -(CH ₂ ) ₃ -NH-(CH ₂ ) ₂ -NH ₂

wherein Rs is a poly(dimethylsiloxane) chain, Mn 5700 [herein after (P5 Ex7)].

[0095] Step 1 : Synthesis of the dimesylate compound of formula:

R _S -[(CH ₂ ) ₃ -0S0 ₂ -CH ₃ ] ₂

A glass reactor was charged with PR1 (45 g, 8.03 mmol), dichloromethane (100 ml) and triethylamine (6.7 ml), and the so obtained reaction mixture was cooled to 0 °C by ice bath. Methanesulfonyl chloride (3.679 g, 32.12 mmol) was added dropwise to the reaction mixture at 0 °C. Thereafter, the reaction was allowed to warm back to room temperature with constant stirring. The completion of the reaction was monitored by NMR. The reaction mixture was poured to saturated NaHCOs solution and extracted with dichloromethane (100 ml thrice). The combined organic layers were dried over anhydrous Na2S0 ₄ and evaporated under reduced pressure to obtain the product. All analyses confirmed the obtainment of the title product, with purity higher than 98%.

[0096] Step 2: Reaction of the dimesylate compound with a diamine A glass reactor was charged the dimesylate compound obtained in step 1 above (40 g, 6.95 mmol) and ethylene diamine (20.88 g, 347.46 mmol). The reaction mixture was stirred at 80 °C for 12 h. The completion of the reaction was monitored by NMR. The solvent was evaporated under reduced pressure and the polymer was purified by water wash (100 ml, thrice). All analyses confirmed the obtainment of the title product, with purity higher than 99%.

[0097] Example 8 - Synthesis of polymer PPG-tetraacid [herein after (PPG-Tac Ex8) of formula:

A glass reactor was charged with trimellitic anhydride (144.1 g, 750 mmol) dissolved in dehydrated DMF (100 ml) under nitrogen atmosphere.

Triethylamine (165 ml) and DMAP (9.16 g, 75 mmol) were introduced to the solution and the mixture was stirred for 30 min at room temperature (25°C). Poly(propyleneglycol) (PPG-diol), as specified above, (250 g, 125 mmol) was dissolved in DMF (100ml) and added dropwise to the mixture over a period of 30 min. The mixture was stirred continuously at 80 °C for 48 hours, until complete conversion of hydroxyl groups of (PPG-diol), which was monitored by NMR. Then the reaction mixture was cooled at room temperature, diluted with dichloromethane and washed with an aqueous 1 N HCI solution (thrice) followed by brine (twice), and finally with water (once). The organic phase was separated and concentrated to give the target product in 100% yield. All analyses confirmed the obtainment of the title product (Mn 2470).

[0098] Example 9 - Synthesis of polymer PPG-tetraamine [herein after (PPG- Tam Ex9) of formula:

2-chloro-4,6-diamino-1 ,3,5-triazine (21.83 g, 150 mmol) was dispersed in a mixture of 2-propanol and water (45 ml, 2: 1 v/v ratio).

Poly(propyleneglycol)-bis(2-aminopropylether) (PPG-diamine) (100 g, 50 mmol) and K2CO3 (27.6 g, 200 mmol) were added to the mixture and stirred continuously at 90 °C for 48 hours. Then, the solvent was evaporated under reduced pressure and dissolved in toluene. The insoluble material was filtered off and the filtrate was washed with water (twice). The organic phase was separated, filtered and concentrated to give the target product in 100% yield. All analyses confirmed the obtainment of the title product (Mn 2206).

[0099] Properties of polymers and compositions of the invention

[00100] Table 1 reports the molecular weight (Mn), the equivalent weight (Ew) and the viscosity m (at 10rad/sec and 30 °C) of each polymer.

[00101] Table 2 reports the ingredients of compositions C1 to C6 prepared

following the procedure described above. Compositions C1 to C3 represent object of the present invention, while compositions C4 to C7 are comparative examples.

[00102] Table 3 reports the experimental viscosity values of said compositions, their average molecular and equivalent weights, their storage and loss moduli.

Table 1

Table 2

Table 3 [00103] As evident from Table 3, the compositions C1 to C3, which are object of the present invention, have the G’ value higher than the G” value, meaning that their elastic behaviour prevails over the viscous one. On the contrary, in the compositions C4 to C7 (not object of the invention) the viscous behavior prevails on the elastic one, the G’ value being lower than the G” value.

[00104] As evident from Tables 2 and 3, the compositions C1 to C3 surprisingly have higher viscosity values than the compositions C4 to C7.

[00105] From a comparison of compositions C2 and C5 having a similar

average equivalent weight, it is noted that C2 (object of the invention) has a viscosity more than 1 order of magnitude higher than C5 (not object of the invention) and a storage modulus G’ of about 30 times higher.

[00106] Although composition C7 is highly cross-linked (i.e. it has a low

equivalent weight), said composition shows very low viscosity and G” largely prevailing on the storage modulus G’. This means that C7 behaves as a viscous fluid and not as an elastic material.