EP1355974A1

EP1355974A1 - Poly (ethynylene phenylene ethynylene polysiloxene (silylene)) and methods for preparing same

Info

Publication number: EP1355974A1
Application number: EP01993643A
Authority: EP
Inventors: Christian Levassort; Franck Jousse; Laurent Delnaud; Pierrick Buvat
Original assignee: Commissariat a lEnergie Atomique CEA
Current assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date: 2000-11-10
Filing date: 2001-11-09
Publication date: 2003-10-29
Also published as: JP2004514005A; WO2002038653A1; US6872795B2; CA2428104A1; FR2816623B1; US20040024163A1; FR2816623A1

Abstract

The invention concerns poly(ethynylene phenylene ethynylene polysiloxene(silylene)) heat-stable polymers preferably having specific molecular weight optionally bearing at the chain end groups derived from a chain limiting agent. The invention also concerns the preparation of said polymers, hardened polymers obtained by heat treatment of said polymers, and matrices comprising said polymers.

Description

POLY (ETHYNYLENE PHENYLENE ETHYNYLENE

POLYSILOXENE (SILYLENE))

AND THEIR PREPARATION PROCESSES

DESCRIPTION

The present invention relates to polymers of poly (ethynylene phenylene ethynylene polysiloxene (silylene)). The present invention relates, in particular, to poly (ethynylene phenylene ethynylene polysiloxene (silylene)) of low viscosity, preferably of determined molecular mass.

The invention further relates to processes for the preparation of said polymers and to the cured products capable of being obtained by heat treatment of said polymers. The polymers according to the invention can in particular be used in matrices for composites. The technical field of the present invention can be defined as that of thermostable plastics, that is to say polymers which can withstand high temperatures which can reach for example up to 600 ° C. The industrial needs for such thermostable plastics have increased enormously in recent decades, particularly in the electronic and aerospace fields.

Such polymers have been developed to remedy the shortcomings of materials previously used in similar applications. Indeed, it is known that metals such as iron, titanium and steel are thermally very resistant, but they are heavy. Aluminum is light but not very resistant to heat, ie up to around 300 ° C. Ceramics such as SiC, Si ₃ N ₄ and silica are lighter than metals and very heat resistant but they are not moldable. This is the reason why many plastics have been synthesized which are light, moldable and have good mechanical properties; these are mainly carbon-based polymers.

Polyimides have the highest heat resistance of all plastics with a thermal deformation temperature of 460 ° C, however these compounds which are listed as being the most stable known at present are very difficult to use. Other polymers such as polybenzimidazoles, polybenzothiazoles and polybenzooxazoles have a heat resistance still higher than that of polyimides but they are not moldable and they are flammable.

Polymers based on silicon such as silicones or carbosilanes have also been widely studied. The latter such as poly (sylylene ethynylene) compounds are generally used as ceramic precursors of the silicon carbide SiC type, resist compounds and conductive materials.

It has recently been shown in document [4] that poly [(pnenyl silylene) ethynylene-1, 3 -phenylene ethynylene] (or MSP) prepared by a synthetic process involving dehydrocoupling polymerization reactions between phenylsilane and m-diethynylbenzene exhibited remarkably high thermal stability. This is confirmed in document [1] which more generally highlights the excellent thermal stability properties of poly (silylene ethynylene phenylene ethynylene) which have a repeating unit represented by the following formula (A):

The synthesis of polycarbosilanes comprising a silane function and a diethynylbenzene by conventional methods with metallic catalysts leads to polymers of low purity containing significant traces of metallic catalyst greatly affecting their thermal properties.

Other improved synthesis methods are presented in document [2]: these are syntheses catalyzed by palladium but which in fact only apply to a very limited number of specific polymers in which the silicon carries example two phenyl or methyl groups.

In particular, it will be noted that the compounds whose repeating unit has been described above by the formula (A) cannot be synthesized by this process. However, it turns out that the SiH bonds of such particularly difficult to obtain compounds are very interesting since they are extremely reactive and can give rise to multiple rearrangements and reactions.

Another process for cross dehydrocoupling of silanes with alkynes in the presence of a catalytic system based on copper chloride and an amine is described in document [3]. This process is however also limited to a few polymers and results in compounds whose structure is partially crosslinked and the average molecular weight by mass very high (10 ⁴ to 10 ⁵ ). These structural defects seriously affect both the solubility properties and the thermal properties of these polymers.

Another synthetic process aiming to remedy the drawbacks of the processes described above, and to prepare pure compounds, without traces of metals, and with excellent, well-defined properties, notably of thermal stability, has been proposed in document [4 ] already mentioned above. This process essentially allows the synthesis of the compounds of formula (A) above in which the silicon carries a hydrogen atom. The process according to [4] is a polycondensation by dehydrogenation of a hydrosilane functionalized with a compound of diethynyl type in the presence of a metal oxide such as MgO according to the following reaction scheme (B):

This process leads to weakly crosslinked polymers with, as shown above, excellent thermal stability, but the mass distribution of which is however very wide.

In another more recent publication [1], the same authors prepared a series of polymers comprising the motif -Si (H) -C≡C- by method (B) and by another more advantageous method, involving the reaction of condensation of dichlorosilane and organomagnesium reagents then the reaction of the product obtained with a monochlorosilane followed by hydrolysis according to the following reaction scheme (C):

Unlike process (B), process (C) makes it possible to obtain polymers without structural defects with good yields and a low mass distribution.

The compounds obtained by this process are perfectly pure and have perfectly characterized thermal properties. These are thermosetting polymers.

This document also discloses the preparation of the above-mentioned polymers reinforced with glass, carbon or SiC fibers.

A patent relating to polymers comprising the very general repeating unit (D):

in which R and R 'relate to many groups known in organic chemistry, has been granted to the authors of documents [1] and [4], it is the document EP-B1-0 617 073 (corresponding to the American patent US- A-5,420,238).

These polymers are prepared essentially by the method of scheme (C) and optionally by the process of scheme (B), and they have a weight average molecular weight of 500 to 1,000,000. This document also describes cured products based on these polymers and their preparation by heat treatment. It is indicated that the polymers of this document can be used as thermostable polymer, fire-resistant polymer, conductive polymer, material for electroluminescent elements. In fact, it appears that such polymers are essentially used as organic precursors of ceramics.

The excellent thermal stability of the polymers prepared in particular in document EP-B1-0 617 073 makes them capable of constituting the resin forming the organic matrix of thermostable composite materials with organic matrices. Many techniques for making composites exist.

In a very general way, the various methods call upon injection techniques (in particular RTM), or prepreg compaction techniques.

Prepregs are semi-finished products of small thickness made of fibers impregnated with resin.

Prepregs which are intended for the production of high performance composite structures, contain at least 50% fiber by volume.

Also, during processing, the matrix must have a low viscosity to penetrate the reinforcing ply and properly impregnate the fiber in order to avoid its distortion and to preserve its integrity. The reinforcing fibers are impregnated either with a resin solution in an appropriate solvent, or with pure resin in the molten state, this is the so-called "hot melt" technique. The technology for manufacturing prepregs with a thermoplastic matrix is largely governed by the morphology of the polymers.

Injection molding is a process which consists in injecting the liquid resin into the textile reinforcement, positioned beforehand in the impression formed by the mold and the counter-mold. The most important parameter is the viscosity which must be between 100 and 1000 mPa.s at the injection temperature which is generally 50 to 250 ° C.

For these two techniques, viscosity is therefore the critical parameter which conditions the ability of the polymer to be used. However, amorphous polymers correspond to macromolecules whose skeletal structure is completely disordered. They are characterized by their glass transition temperature (Tg) corresponding to the transition from the glassy state to the rubbery state. Beyond Tg, thermoplastics are however characterized by a high creep resistance.

The polymers prepared in document EP-B1-0 617 073 are compounds which are in powder form. The inventors were able to show, by reproducing the syntheses described in this document, that the polymers prepared would produce glass transition temperatures close to 50 ° C.

Before this temperature, the viscosity of the polymer is infinite and beyond this temperature, the viscosity decreases as the temperature is increased.

However, this drop in viscosity is not sufficient for the polymer to be able to be used by methods conventionally used in the world of composites such as RTM and prepreg already described above.

There is therefore a need for a polymer of structure similar to those described in patent EP-B1-0 617 073, that is to say having all their advantageous properties, in particular thermal stability but whose viscosity is sufficiently low. so that they can be implemented, manipulated, "processable" at temperatures for example from 100 to 120 ° C. which are the temperatures commonly used in injection or impregnation techniques.

The object of the invention is to provide polymers which meet inter alia these needs which do not have the defects, drawbacks, limitations and disadvantages of the polymers of the prior art as shown in particular by document EP-B1-0 617,073, and which solve the problems of the prior art.

The object of the invention is also to provide a process which makes it possible to prepare said polymers.

This object, and still others are achieved in accordance with the invention by a polymer of poly (ethynylene phenylene ethynylene polysiloxene (silylene)), said polymer corresponding to the following formula (I):

or to the following formula (la)

in which the phenylene group of the central repeating unit can be in the form o, m or p; R represents a halogen atom (such as F, Cl, Br and I), an alkyl group (linear, or branched) having from 1 to 20 carbon atoms, a cycloalkyl group having from 3 to 20 carbon atoms (such as methyl, ethyl, propyl, butyl, cyclohexyl), an alkoxy group having from 1 to 20 carbon atoms (such as methoxy, ethoxy, propo y), an aryl group having from 6 to 20 carbon atoms (such as a phenyl group), an aryloxy group having 6 to 20 carbon atoms (such as a phenoxy group), an alkenyl group (linear, or branched) having 2 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms (such as vinyl, allyl, cyclohexenyl), an alkynyl group having 2 to 20 carbon atoms (such as ethynyl, propargyl), an amino group, an amino group substituted by one or two substituents having from 2 to 20 carbon atoms (such as dimethylamino, diethylamino, ethylmethylamino, methylphenylamino) or a group silanyl having from 1 to 10 silicon atoms (such as silyl, disilanyl (-SiH ₅ ), dimethylsilyl, trimethylsilyl and tetramethyldisilanyl), one or more hydrogen atoms linked to the carbon atoms of R can be replaced by atoms of halogens (such as F, Cl, Br and I), alkyl groups, alkoxy groups (such as methoxy, ethoxy and propoxy), aryl groups, aryloxy groups (such as a phenoxy group), amino groups, amino groups substituted with one or two substituents or silanyl groups; n is an integer from 0 to 4 and q is an integer from 1 to 40; R 'represents

in which p is an integer from 1 to 40 and R _x and R ₂ which may be the same or different represent a hydrogen atom, a halogen atom, an alkyl group having from 1 to 20 carbon atoms, a group cycloalkyl having 3 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, an alkenyl group having from 2 to 20 carbon atoms, a cycloalkenyl group having from 3 to 20 carbon atoms, an alkynyl group having from 2 to 20 carbon atoms, one or more of the hydrogen atoms bonded to the atoms carbon atoms of R _x and R ₂ may be replaced by halogen atoms, alkyl groups, alkoxy groups, aryl groups, aryloxy groups, amino groups, disubstituted amino groups or silanyl groups, examples of these groups have already been mentioned above for R; Y represents a halogen atom, a hydrogen atom or group derived from a chain-binding agent.

The polymers according to the invention have a structure substantially similar to that of the polymers of document EP-B-0 617 073 with the fundamental exception, however, of the fact that the silicon atom of the silylene groups carries, on the one hand, a hydrogen atom and, on the other hand, a particular substituent, which is specifically a polysiloxene group

_T Preferably, Ri and R ₂ are identical. Preferably, moreover, they represent an alkyl group of 1 to 20 C, more preferably a methyl group. It has been found that due to the presence of this specific group, the polymer according to the invention intrinsically has a low viscosity, namely a viscosity generally less than 100 Pa.s at 140 ° C. This low viscosity is obtained, fundamentally, by virtue of the polysiloxene group, whatever the nature of the group Y, in particular it is not compulsory for Y to be a group derived from a chain-limiting agent.

Indeed, the influence of the specific polysiloxene group is such that the low viscosity is obtained whatever the length of the polymer chain. It should be noted that nowhere in the prior art are polymers having the specific structure according to the invention described and, furthermore, no relationship has ever been established between the presence of the specific polysiloxene groups and the viscosity, and a fortiori, obtaining a low viscosity.

The polymers according to the invention can, moreover, also differ from the polymers of document EP-B1-0 610 073, due to the presence at the chain end of groups Y derived from a chain-limiting agent.

This or these structural difference (s) has (have) very little influence on the advantageous properties of these polymers, in particular the thermal stability properties of the polymer which are hardly affected.

On the other hand, the presence of the specific polysiloxene groups, mentioned above, has the effect that the polymer (I) or (la) according to the invention has perfectly defined and modular rheological properties. In addition, if the group Y is a group resulting from a chain limiter, the presence at the chain end of this group will have precisely the effect that the polymer of formula (I) or (la) will have a length and therefore a mass molecular molecules, perfectly defined like its rheological properties.

Y can be H or a halogen atom, such as Cl, I, Br or I, preferably Cl, or another of hydrogen.

Y can also be a group resulting from a chain-limiting agent.

The nature of the group Y depends on the nature of the chain-limiting agent from which it is derived, Y may, in the case of the polymers of formula (I), represent a group of formula (II):

wherein R "'has the same meaning as R and can be the same or different from the latter, and n' has the same meaning as n and can be the same or different from the latter.

Or then Y could, in the case of polymers of formula (la), represent a group of formula (III):

If ^" R ₄ (III)

Rs

in which R ₃ , R ₄ and R ₅ which may be identical or different have the same meaning as R, already given above.

A particularly preferred polymer of formula (I) according to the invention corresponds to the following formula:

where Z is

q is an integer from 1 to 40, for example 10, and where p is an integer from 1 to 40.

The invention also relates to polymers, preferably polymers of determined molecular mass, capable of being obtained by hydrolysis of the polymers of formula (la), in which Y is a group derived from a chain-limiting agent, and corresponding to the following formula (Ib):

in which R, R ', R' ', n and q have the meaning already given above.

The molecular mass of the polymers (I) and (la) according to the invention is, in the case where the group Y is a group derived from a chain-limiting agent, perfectly defined and the length of the polymer and therefore its molecular mass can be easily controlled by metered additions of chain limiter in the reaction mixture reflected by varying proportions of group Y in the polymer.

Thus, according to the invention the molar ratio of the Y groups (chain limiters) at the end of the chain to repeating units ethynylene phenylene ethynylene polysiloxene (silylene) is it generally from 0.01 to 1.5. Preferably, this ratio is 0.25 to 1.

Similarly according to the invention, the molar proportion of the Y groups (chain limiters) at the end of the chain is generally from 1 to 60 and preferably from 20 to 50% of the polymer of formula (I) or (la).

The number-average molecular mass of the polymers (I), (la) and (Ib), according to the invention, in the general case, is generally from 400 to 1,000,000 and their weight-average molecular mass is generally from 400 to 1,000,000.

The number-average molecular mass of the polymers (I), (la) and (Ib), according to the invention, in the case where Y is a group derived from a chain-limiting agent, and which is then perfectly defined, is generally 400 to 50,000 and the weight average molecular weight is 600 to 100,000.

These masses being determined by gel permeation chromatography (GPC) from a polystyrene calibration.

The viscosity of the polymer according to the invention, as indicated above, is low, that is to say that it is, for example, in the range of 0.1 to 500 mPa. s for temperatures of 50 to 150 ° C., regardless of the molecular weight of the polymer, that is to say without the need to use a group Y derived from a chain-limiting agent .

Indeed, the low viscosity is due to the specific polysiloxene groups carried by the silicon. If we want to define the viscosity of the polymer even better, we can do this by controlling its molecular mass. Indeed, advantageously, due to the presence of Y groups derived from a chain-limiting agent, the molecular mass is generally within the aforementioned advantageous range, which makes it possible, moreover, to perfectly control the viscosity of the polymers, which is in any case already sufficiently low, due to the presence of the polysiloxene groups, for the desired applications.

The viscosity also depends on the nature of the groups carried by the aromatic rings.

According to the invention, it is thus possible to modify at will depending on the technological constraints of implementation of the composite, the viscosity of the polymer.

The viscosity is also linked to the glass transition temperature (Tg). The glass transition temperature of the polymers according to the invention will therefore generally be from -250 to + 10 ° C.

The invention further relates to a first process for the preparation of a poly (ethynylene phenylene ethynylene polysiloxene (silylene)) polymer, preferably of determined molecular mass, optionally bearing at the end of the chain groups derived from a chain limiting agent , said polymer corresponding to formula (I) below:

in which the phenylene group of the central repeating unit can be in the form o, m or p, and R, R ', Y, n, p (of R'), and q have the meaning already given above.

Said process comprising the reaction of a Grignard reagent of general formula (IV):

in which the phenylene group may be in the form o, m or p, and R, and n have the meaning indicated above for the formula (I), and X represents a halogen atom such as Cl Br or I, optionally mixed with a chain limiting agent of formula:

Y - MgX (V) X having the meaning already given above, and Y is a group chosen from the groups of formula:

wherein R "'has the same meaning as R and can be the same or different from the latter, and n' has the same meaning as n and can be the same or different from the latter; with a dihalide (dihalosilane) of general formula ( VII):

i

X If X (Naked)

R '

in which R ′, and X have the meaning already indicated above, in the presence of an aprotic solvent, an optional step for treating the reaction product of the compounds (IV) and (VII), in the case where the reaction n 'involves no chain limiting agent with a monohalosilane, then a hydrolysis step to give the final polymer of formula (I).

A variant of the first process according to the invention makes it possible to prepare a poly (ethynylene phenylene ethynylene polysiloxene (silylene)) polymer of formula (la):

in which the phenylene group of the central repeating unit can be in the form o, m, or p, and R, R ', Y, p (of R') q and n have the meaning already given above; said process comprising the reaction of a GRIGNARD reagent of general formula (IV) above, and of a dihalide of general formula (VII), already indicated above, optionally in admixture with a chain-limiting agent of formula:

X (VIII)

in which X has already been defined above and Y is chosen from the groups of formula:

: ι ₃

in which R ₃ , R ₄ and R _{5, which are} identical or different, have the meaning already given above, and in the presence of an aprotic solvent, to give the final polymer of formula (la).

The first process of the invention, in this variant and in the case where Y is a group derived from a chain limiter, can, moreover, also, comprise a final hydrolysis step to give the polymer of formula (Ib ) already mentioned above.

The invention also relates to a second process for the preparation of a polymer of poly (ethynylene phenylene ethynylene polysiloxene (silylene)), preferably of determined molecular mass, optionally bearing at the chain end groups derived from a chain limiting agent, said polymer corresponding to the following formula - (I):

in which the phenylene group of the central repeating unit can be in the form o, m or p, and R, and R ', Y, n, q and p (of R') have the meaning already given above.

Said process comprising the reaction of a compound of formula (X):

in which the phenylene group may be in the form o, m, or p and R and n have the meaning already indicated above for formula (I), optionally in admixture with a chain-limiting agent of formula (XI):

in which R '' 'has the same meaning as R and can be the same or different from the latter, and has the same meaning as n and can be the same or different from the latter with a compound of formula (XII):

H- If ^" H

(Xπ)

R '

wherein R 'has the meaning already mentioned above, in the presence of a basic metal oxide to give the final compound of formula (I).

A. variant of the second process according to the invention makes it possible to prepare a polymer of poly (ethynylene phenylene ethynylene polysiloxene (silylene)), preferably, of determined molecular mass, optionally carrying at the chain end groups derived from a chain limiting agent, of formula (la):

in which the phenylene group of the central repeating unit can be in the form, o, m or p, and R, R ', Y, q, n, and p have the meaning already given above; said process comprising reacting a compound of formula (X) already mentioned above, with a compound of formula (XII), already mentioned above, optionally in admixture with a chain-limiting agent (monohydrosilane) of formula ( XIII):

R3

R ₅

in which R ₃ , R ₄ and R _{5, which are} identical or different, have the meaning already given above, in the presence of a basic metal oxide to give the final compound of formula (la). The second method of the invention, in this variant can, moreover, comprise a final hydrolysis step to give the polymer of formula (Ib) already mentioned above. According to the invention, the presence, as a substituent, on the silicon atom of the silylene groups, of a polysiloxene group, surprisingly gives the polymers according to the invention a low viscosity and, moreover, , perfectly controlled, if Y is a group derived from a chain-limiting agent, in other words, the polymers according to the invention have in all cases excellent rheological properties.

In addition, advantageously, according to the invention, and surprisingly, the control of the masses of the polymers of formula (I), (la) and (Ib) can be obtained by adding to the reaction medium a reactive species also called chain limiting agent which blocks the polymerization reaction without affecting the overall yield of the reaction.

This reactive species is generally an analogue of one of the main reactants, but which has only one function allowing coupling. When this species is introduced into the polymer chain, growth is stopped.

By making metered additions of chain limiter, it is possible according to the invention to easily control the length of the polymer and, consequently, its viscosity; although, and we emphasize again this fact, the low viscosity of the polymer, according to the invention is already obtained, thanks to the polysiloxene groups.

The fundamental principle of both the first process according to the invention and the second process according to the invention, in its advantageous embodiment, namely the control of the molecular mass and therefore of the viscosity of the polymer by adding to the reaction mixture of a chain limiting agent is identical. The same principle could be applied with slight adaptations to the other possible synthesis methods for the polymers of formula (I) or (la).

Whether in the first process or in the second process in their advantageous embodiments, the length of the polymer and therefore its molecular weight and consequently its viscosity are in direct correlation with the molar percentage of chain-limiting agent. This molar percentage is defined by the mole ratio of the chain-limiting agent to the total of the moles of chain-limiting agent and of diacetylene compounds of formula (IV) or (X) x 100. This percentage can range from 1 to 60%, preferably from 20 to 50%.

There was no indication in the literature relating to the influence on the viscosity of the polysiloxene groups. There was, moreover, in particular in the documents cited above, no indication relating to the control, to the control, of the molecular weights of polymers of the poly (silylene ethynylene) type and a fortiori there was in the documents of the prior art no mention of a relationship between the distribution of molecular weights and the viscosities of these polymers.

Thus, the fact of choosing to advantageously introduce a chain limiter in the polymer synthesis mixture in order to control its molecular weight is neither disclosed nor suggested in the prior art.

In the case of the synthesis process involving a metal oxide as described in documents [1], [4] and patent EP-B1-0 617 073 and which corresponds substantially to the second preparation process according to l invention, molecular weight is related to the degree of activation of the catalyst [4]. As this is highly hygroscopic, it is very difficult to predict the molecular masses a priori. The less the catalyst is activated and the lower the masses, but this drop is accompanied by a significant drop in the yield of the polymerization reaction. In addition, the distribution can be so wide that several fractions of different mass can be isolated by selective fractionation.

In the case of the magnesium synthesis described in document [1] and the aforementioned patent and which corresponds substantially to the first preparation process according to the invention, it is quite obvious that the molecular masses will be governed by the nature and the quantity solvent as well as the reaction temperature. However, these parameters are very difficult to optimize, and do not allow the mass range to be varied significantly. Furthermore, the drop in masses is inevitably accompanied by a significant drop in reaction yield. Finally, the mass distribution is also influenced by the stoichiometry of the reaction. In the case of synthesis by magnesian route, this parameter will only be relevant if one of the two reagents is in very large excess, which will have the consequence of greatly limiting the yield.

According to the invention, advantageously, and surprisingly, one does not play on any of the synthesis parameters mentioned above and one adopts a totally different synthesis strategy by using in the reaction medium a reactive species which comes to block the reaction polymerization without affecting the overall yield of the reaction.

In addition, the first preparation process of the invention makes it possible to dispense with - when a chain limiter is used - a step in the process of EP-B1-0 617 073 which involves a silylated monohalogenated compound , which results in shorter reaction times as well as substantial savings in reagents.

In the general case, or one does not use the chain limiter, then the first preparation process is the same as that described in document EP-B1-0 617 073, that is to say that beforehand on final hydrolysis, the reaction product of the GRIGNARD reagent (IV) and the dihalide (VII) is treated with a monohalide. The invention also relates to the hardened product capable of being obtained by heat treatment at a temperature of 50 to 700 ° C of the polymer described above.

The hardened product has an infinite mass. It advantageously comes from a polymer with a mass of 500 to 20,000 and by weight of 600 to 100,000.

Finally, the invention also relates to a composite matrix comprising the polymer described above.

The invention will be better understood on reading the detailed description which follows, given by way of illustration and not limitation.

In detail, the first process for preparing a poly (ethynylene phenylene ethynylene polysiloxene (silylene)) polymer according to the invention is substantially similar to that described in document EP-B1-0 617 073 with the exception, however, of the presence of the polysiloxene substituent and of the possible incorporation into this mixture in accordance with the invention of a chain-limiting agent, of the final treatment of the polymers and optionally of the molar ratio of the organomagnesium and dichlorosilane reagents. We can therefore, relative to the conditions of this process, refer to this document EP-B1-0 .617 073 which is incorporated herein by reference. The Grignard reagents of formula (IV) used in the first preparation process according to the invention are in particular those described in document EP-B1-0 617 073 on pages 5 to 7 (Formulas (3) and (8) to (20). The optional chain-limiting agent of formula (V) can be a monoacetylene organomagnesium compound of formula:

R "', X and n' have already been defined above. Examples of the monohalosilane are given in patent EP-B1-0 617 073 on page 9 (formula (5)).

Examples of the monoacetylene compounds from which the monoacetylene organomagnesium compounds (V) are derived are the following: phenylacetylene, 4-ethynyltoluene 4-ethynylbiphenyl, 1-ethynyl 4-methoxybenzene.

The Grignard reagent (IV), optionally a mixture with the chain-limiting compound corresponding to the above formula, is reacted with the dihalosilane of general formula (VII).

Examples of such dihalosilanes are the dichlorosilanes described on pages 7 to 9 of patent EP-B1-0 -617 093 and correspond in particular to formulas (21) to (26) given in this document. However, it should be noted that basically according to the invention one of the substituents of these dihalosilanes is necessarily H and the other substituent is a specific polysiloxene group, which is not the case in the aforementioned patent. The conditions of the polymerization reaction such as the solvent, the reaction time, the temperature, etc. (excluding "post-treatment") are substantially the same as those described in document EP-B1-0 617 073 to which reference is made in particular on page 14. The only differences in this step proper polymerization relate, in addition to the specific group polysiloxene, the optional addition of an additional reagent chain limiter.

The reaction conditions are moreover substantially the same.

However and according to the invention, preferably, the ratio of the number of acetylenic function by the number of halogen functions carried by the silane must be as close as possible to 1, and preferably from 0.9 to 1.1. The molar ratio of “phenylacetylene” to “diethynylbenzene” is preferably between 0.01 and 1.5 and ideally between 0.25 and 1 (percentage from 1 to 60%).

This also applies to the variant of the first process in which the chain limiter is a monohalosilane.

According to the invention, and in the case where a chain limiter, whatever it is, is used, following the polymerization reaction, a final hydrolysis step is carried out directly, so in this case it is freed a step compared to the analogous process of the prior art, in particular in the case where the chain limiter is an organomagnesium.

In fact, in document EP-B1-0 617 073, post-treatment of the already prepared polymer, the molecular mass of which is fixed, is carried out by a monohalosilane then hydrolysis. It should be noted that, in this case, the monohalosilane does not play the role of chain limiter since it is not on the contrary of the present invention - in the advantageous case where a chain limiter included in the starting reaction mixture and that its action has no influence on the molecular weight of the polymer.

However, in the most general case of preparation of the polymers according to the invention, where a chain limiter is not used, the operation is carried out in the same way as in the EP patent, cited above, with treatment of the polymerization product with a monohalosilane and hydrolysis. According to the invention, at the end of the reaction, the polymer

(with chain limiting groups) is hydrolyzed by a volume, for example from 0.1 to 50 ml per gram of polymer of an acid solution, for example about 0.01 to 10 N of hydrochloric acid or sulfuric acid. The ideal solvent is tetrahydrofuran. In this case, the reaction mixture is then decanted and the solvent of the organic phase is substituted with a volume for example of 0.1 to 100 ml per gram of polymer and ideally of 1 to 10 ml per gram of polymer for any type of solvent immiscible with water, such as xylene, toluene, benzene, chloroform, dichloromethane or alkane with more than 5 carbons. In the case of a reaction carried out in a water immiscible solvent, this step can be omitted. The organic phase is then washed for example from 1 to 5 times and preferably 2 to 3 times with a volume of water. for example from 0.1 to 100 ml per gram of polymer and ideally from 1 to 10 ml per gram of polymer, so as to neutralize the organic phase and extract all the impurities such as magnesium and halogen salts therefrom . The pH of the organic phase should preferably be between 5 and 8 and ideally between 6.5 and 7.5. After evaporation of the solvent, the polymer is dried under a vacuum of between 0.1 and 500 mbar at a temperature between 20 and 150 ° C for a time between 15 minutes and 24 hours.

The second process for preparing the polymers of formula (I) is a process using dehydrogenation in the presence of a basic metal oxide. Such a process differs from the analogous process described in documents [1] and [4] as well as in document EP-B-0 617 073 only in that a chain-limiting agent is optionally added to the reaction mixture and basically by the presence of polysiloxene groups in one of the reagents.

The reaction mixture comprises a compound of formula (X) for example: 1, 3-diethylnylbenzene and optionally a chain-limiting agent which in this second process is a monoacetylene (XI) analogous to that already described above for the first process.

Compound (X), optionally mixed with one chain-limiting agent, reacts with a trihydrosilane of formula (XII).

The basic metal oxide used is preferably chosen from oxides of alkali metals, alkaline earth metals, oxides of lanthanides, oxides of scandium, yttrium, thorium, titanium, zirconium, hafnium, copper, zinc, cadmium and their mixtures.

Examples of such oxides are given in document EP-B-0 617 073 on pages 16 and 17 to which explicit reference is made here. These oxides can be subjected to an activation treatment as described in patent EP-B1-0 617 073.

The cured products prepared by heat treatment of the polymers according to the invention are for example produced by melting this polymer or by dissolving it in a suitable solvent, then optionally putting it in the desired form and heating it in a gaseous atmosphere. air, nitrogen or inert gas such as argon or helium. The temperature of the treatment generally ranges from 50 to 700 ° C, preferably from 100 to 400 ° C and more preferably from 150 to 350 ° C, and the heating is generally carried out for a period of one minute to 100 hours. The curing reaction can optionally be carried out in the presence of a curing agent and the polymer according to the invention can also be mixed with other resins or polymers.

Due to the analogous structure of the polymers according to the invention and of the polymers of the document

EP-B1-0 617 073, their hardening process is substantially identical and reference may be made to this document page 17 for more details.

The preparation of organic matrix composites comprising the polymer of the invention is detailed below. The invention will now be described with reference to the following examples given by way of illustration and not limitation.

Example 1

Preparation of poly ([hexa ethyltrisiloxene] silylene ethynylene phenylene ethynylene)

In a three-liter three-necked flask placed under argon and containing 6.4 g (263 mmol) of magnesium powder in suspension in 100 ml of anhydrous THF, 25.88 g (257 mmol) of bromoethane in solution in 100 ml of Anhydrous THF are introduced dropwise so as to maintain the reflux. The reflux is maintained for one hour after the end of the addition. 14.1 g (113 mmol) of 1, 3-diethynylbenzene dissolved in 100 ml of anhydrous THF are then introduced dropwise and left under stirring and under reflux for one hour.

36.5 g (113 mmol) of dichlorohexamethyltrisiloxene-silane in solution in 100 ml of anhydrous THF are then introduced dropwise under reflux. The solution is then left under stirring and reflux for one hour. The polymer thus formed is then hydrolyzed by adding 50 ml of hydrochloric acid at 35% by mass in solution in 100 ml of water. The reaction medium is separated into two fractions, one aqueous, the other organic. The aqueous phase then undergoes a change of solvent, THF being replaced by 200 ml of chloroform. The polymer in solution in chloroform is then washed three times with 100 ml of water. The organic solution is then dehydrated by passage over a bed of magnesium sulfate. The polymer is then obtained by evaporation of the solvent. The polymer is finally purified by drying under 0.4 mbar at 20 ° C. 34 g (80% yield) of polymer are thus obtained, which is in the form of a yellow oil. The number average molecular mass of this compound is 11,500 for a mass average mass of 5,500 (polydispersity of 2.1). These masses were determined by GPC from a polystyrene calibration.

Example 2

Preparation of poly ([hexamethyltrisiloxene] silylene ethynylene phenylene ethynylene) with chain termination of aromatic acetylene type with 20 mol% of chain limiter

In a three-liter three-necked flask placed under argon and containing 6.4 g (263 mmol) of magnesium powder in suspension in 100 ml of anhydrous THF, 25.88 g (257 mmol) of bromoethane in solution in 100 ml of Anhydrous THF, 25.88 g (257 mmol) of bromoethane in solution in 100 ml of anhydrous THF are introduced dropwise so as to maintain the reflux. The reflux is maintained for one hour after the end of adding. A mixture of 12.67 g (100.6 mmol) of 1, 3-diethynylbenzene and 2.56 g (25.1 mmol) of phenylacethylene in solution in 100 ml of anhydrous THF are then introduced dropwise and allowed to stir. and under reflux for one hour.

36.5 g (113 mmol) of dichlorohexamethyltrisiloxene-silane in solution in 100 ml of anhydrous THF are then introduced dropwise under reflux. The solution is then left under stirring and reflux for one hour. The polymer thus formed is then hydrolyzed by adding 50 ml of hydrochloric acid at 35% by mass in solution in 100 ml of water. The reaction medium is separated into two fractions, one aqueous, the other organic. The aqueous phase then undergoes a change of solvent, the THF being replaced by 200 ml of chloroform. The polymer in solution in chloroform is then washed three times with 100 ml of water. The organic solution is then dehydrated by passage over a bed of magnesium sulfate. The polymer is then obtained by evaporation of the solvent. The polymer is finally purified by drying under 0.4 mbar at 20 ° C. 33 g (78% yield) of polymer are thus obtained, which is in the form of a yellow oil. The number average molecular mass of this compound is 5,000 for a mass average mass of 2,150 (polydispersity of 2.3). These masses were determined by GPC from a polystyrene calibration. REFERENCES

[1] "New Highly Heat-Resistant Polymers containing Silicon: Poly (silyleneethynylenephenylene éthynylène) s" by ITOH M., INOUE K., IWATA K., MITSUZUKA M. and KAKIGANO T., Macromolecules, 1997, 30, pp. 694 - 701.

[2] CORRIU Robert J. P. et al., Journal of polymer science: Part C: Polymer Letters, 1990, 28, pp. 431 - 437.

[3] “Copper (I) chloride catalyzed cross dehydrocoupling reactions between silanes and ethynyl compounds. A new method for the copolymerization of silanes and alkynes "by Liu H. Q.; HARROD J. F. The Canadian Journal of Chemistry, 1990, vol. 68, pp. 1,100 - 1,105.

[4] "A novel synthesis and extremely high Thermal stability of

Poly [(phenylsilylene) - (ethynylene-1, 3-phenylene ethynylene)] ”by ITOH M., INOUE K., IWATA K., MITSUZUKA M., KAKIGANO T.; Macromolecules, 1994, 27, pp. 7,917 - 7,919.

Claims

1. Polymer of poly (ethynylene phenylene ethynylene polysiloxene (silylene)), said polymer corresponding to formula (I) below:

or to the following formula (la)

in which the phenylene group of the central repeating unit can be in the form o, m or p; R represents a halogen atom (such as F, Cl, Br and I), an alkyl group (linear, or branched) having 1 with 20 carbon atoms, a cycloalkyl group having from 3 to 20 carbon atoms (such as methyl, ethyl, propyl, butyl, cyclohexyl), an alkoxy group having from 1 to 20 carbon atoms (such as methoxy, ethoxy, propoxy ), an aryl group having 6 to 20 carbon atoms (such as a phenyl group), an aryloxy group having 6 to 20 carbon atoms (such as a phenoxy group), an alkenyl group (linear, or branched ) having from 2 to 20 carbon atoms, a cycloalkenyl group having from 3 to 20 carbon atoms (such as vinyl, allyl, cyclohexenyl), an alkynyl group having from 2 to 20 carbon atoms (such as ethynyl, propargyl), an amino group, an amino group substituted by one or two substituents having from 2 to 20 carbon atoms (such as dimethylamino, diethylamino, ethylmethylamino, methylphenylamino) or a silanyl group having from 1 to 10 silicon atoms (such as silyl, disilanyl (-Si ₂ H ₅ ), dimethylsilyl, trimethylsilyl and tee tramethyldisilanyl), one or more hydrogen atoms linked to the carbon atoms of R can be replaced by halogen atoms (such as F, Cl, Br and I), alkyl groups, .alkoxy groups (such as methoxy , ethoxy and propoxy), aryl groups, aryloxy groups (such as a phenoxy group), amino groups, amino groups substituted by one or two substituents or silanyl groups; n is an integer from 0 to 4 and q is an integer from 1 to 40; R 'represents

in which p is an integer from 1 to 40 and Ri and R ₂ which may be the same or different represent a hydrogen atom, a halogen atom, an alkyl group having from 1 to 20 carbon atoms, a cycloalkyl group having from 3 to 20 carbon atoms, an alkoxy group having from 1 to 20 carbon atoms, an aryl group having from 6 to 20 carbon atoms, an aryloxy group having from 6 to 20 carbon atoms, an alkenyl group having from 2 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, one or more of the hydrogen atoms linked to the carbon atoms of Ri and R ₂ may be replaced by halogen atoms, alkyl groups, alkoxy groups, aryl groups, aryloxy groups, amino groups, disubstituted amino groups or -silanyl groups, examples of these groups have already been cited above. above for R; Y represents a halogen atom, a hydrogen atom or group derived from a chain-limiting agent.

2. Polymer according to claim 1, in which R _x and R ₂ are identical and preferably represent an alkyl group of 1 to 20 C.

3. Polymer according to claim 2, in which Ri and R ₂ are a methyl group.

4. Polymer of formula (I) according to claim 1, in which Y, which is a group derived from a chain-limiting agent, represents a group of formula (II):

5. Polymer of formula (la) according to claim 1, in which Y, which is a group derived from a chain-limiting agent, represents a group of formula (III):

R ₃

R ₅ wherein R ₃ , R ₄ and R ₅ which may be the same or different have the meaning already given for R in claim 1.

6. Polymer according to claim 1 corresponding to the following formula:

where Z is

q is an integer from 1 to 40, and where p is an integer from 1 to 40.

7. Polymer molecular weight determined according to claim 1 which can be ^'obtained by hydrolysis of a polymer of formula (Ia) wherein Y is a group derived from a chain-limiting agent, said polymer corresponding to the following formula (Ib):

in which R, R ', n and q have the meaning already given in claim 1.

8. Polymer according to any one of claims 1 to 6, in which the molar ratio of the Y groups, chain limiters, at the end of the chain to the ethylnylenephenylene ethynylene polysiloxene (silylene) repeating units is from 0.01 to 1.5, preferably 0.25 ^" to 1.

9. Polymer according to any one of claims 1 to 6, in which the molar proportion of the Y groups, chain limiters, of chain end is from 1 to 60%, preferably from 20 to 50%

10. Polymer according to any one of claims 1 to 9 having a number average molecular weight of 400 to 1,000,000.

11. Polymer according to any one of claims 1 to 9 having a weight average molecular weight of 400 to 1,000,000.

12. Polymer according to any one of claims 1 to 11, in which Y is a chain-limiting group, and whose number average molecular weight is from 400 to 50,000 and the weight average molecular weight is from 600 to 100 000.

13. Polymer according to any one of claims 1 to 12 having a viscosity of 0.1 to 500 mPa.s.

14. Polymer according to any one of claims 1 to 13 having a glass transition temperature Tg of -250 to + 10 ° C.

15., Process for the preparation of a poly (ethynylene phenylene ethynylene silylene) polymer, preferably of determined molecular mass, optionally bearing at the end of the chain groups derived from a chain limiting agent, said polymer corresponding to the formula ( I) of claim 1:

said process comprising the reaction, of a Grignard reagent of general formula (IV):

in which the phenylene group may be in the form o, m or p, and R and n have the meaning already given in claim 1 for formula (I) and X represents a halogen atom such as Cl, Br or I , optionally mixed with a chain limiting agent of formula:

Y - MgX (V)

X having the meaning already given above, and Y is a group chosen from the groups of formula:

in which R "'has the same meaning as R and can be the same or different from the latter, and n' has the same meaning as n and can be the same or different from the latter; with a dihalide of general formula (VII):

H

x- -sr X

(VU)

R '

in which R ′ and X have the meaning already given in claim 1, in the presence of an aprotic solvent, an optional step for treating the reaction product of compounds (IV) and (VII) in the case where the reaction does not involves no chain limiting agent with a monohalosilane, then a hydrolysis step, to give the final polymer of formula

(I) •

16. Process for the preparation of a poly (ethynylene phenylene ethynylene silylene) polymer, preferably of determined molecular mass, optionally bearing groups originating from a chain-limiting agent, said polymer corresponding to formula (la) of claim 1:

said process comprising reacting a GRIGNARD reagent of general formula (IV) as defined in claim 15 and of a dihalide of general formula (VII), as defined in claim 15, optionally in admixture with an agent formula chain limiter:

Y - X (VIII)

in which X represents a halogen atom such as Cl, Br or I and Y is chosen from the groups of formula:

the

If R4

(IX)

Rs in which R ₃ , R ₄ and R _{5, which are} identical or different, have the meaning already given for R in claim 1, in the presence of an aprotic solvent, to give the final polymer of formula (la).

17. The method of claim 16, further comprising a final hydrolysis step, whereby the polymer of formula (Ib) according to claim 7 is obtained.

18. Process for the preparation of a poly (ethynylene phenylene ethynylene polysiloxene (silylene) polymer, preferably of determined molecular mass, optionally bearing at the end of the chain groups derived from a chain limiting agent, said polymer corresponding to the formula (I) of claim 1:

said process comprising the reaction of a compound of formula (X):

in which the phenylene group may be in the form o, m, or p and R and n have the meaning already given in claim 1 for formula (I), optionally in admixture with a chain-limiting agent of formula (XI) :

in which R '' 'has the same meaning as R and can be identical or different from the latter, and n' has the same meaning as n and can be identical or different from the latter with a compound of formula (XII):

H ^' Si- H

(Xπ)

R ' wherein R 'has the meaning already given in claim 1, in the presence of a basic metal oxide to give the final compound of formula (I).

19. Process for the preparation of a poly (ethynylene phenylene ethynylene polysiloxene (silylene)) polymer, preferably of determined molecular mass, optionally bearing at the end of the chain groups derived from a chain limiting agent, said polymer corresponding to the formula (la) of claim 1:

said process comprising reacting a compound of formula (X) already defined in claim 18, with a compound of formula (XII) already defined in claim 18, optionally in admixture with a chain-limiting agent (monohydrosilane) of formula (XIII): R ₃

R ₄ If H

(Xiπ)

Rs

wherein R ₃ , R ₄ , R _{5, which are} identical or different, have the meaning already given for R in claim 1, in the presence of a basic metal oxide to give the final compound of formula (la).

20. The method of claim 19, further comprising a final hydrolysis step, whereby the polymer of formula (Ib) according to claim 7 is obtained;

21. The method of claim 15 or claim 18, wherein the molar percentage of chain limiting agent in the mixture of diacetylene compounds of formula (IV) or (X) and chain limiter is from 1 to 60% , preferably from 20 to 50%.

22. Cured product capable of being obtained by heat treatment at a temperature of 50 to 700 ° C of the polymer according to any one of claims 1 to 14.

23. Matrix for composite comprising the polymer according to any one of claims 1 to 14.