WO1995019578A1 - Optical material for making optical guides - Google Patents

Abstract

Polymeric optical materials for transmitting and/or guiding light are provided as a solution to the problem of providing a transparent optical material which does not attenuate light while having high temperature stability and a high glass transition temperature. Said material is a polymer including chiral units (MC) such as 1-1' binaphthalene 2-2'-substituted by radicals other than hydrogen, or biphenylene 2-2'- and 6-6'-substituted by radicals other than hydrogen.

Description

OPTICAL MATERIAL FOR USE IN THE MANUFACTURE OF OPTICAL GUIDES

TECHNICAL AREA :

The field of the invention is that of optics and optoelectronics and, more particularly, of everything relating to the transmission and guiding of light. This refers, in particular, to optical guides, such as fibers, confinement layers or interconnection elements in an all-optical or hybrid integrated circuit: electronic-optical.

More specifically, the invention relates to optical materials of a polymeric nature and intended to be used for the transmission and / or guiding of light.

It therefore goes without saying that one of the essential qualities required for these polymer optical materials is to have low optical attenuation in ranges of wavelengths which are more or less wide.

PRIOR ART:

Numerous polymeric materials useful for transmitting light are already known. Among these, mention may, for example, be made of polymethylmethacrylate (PMMA) and polystyrene (PS) or polycarbonate (PC). These conventional polymers transmit light relatively well but suffer from two major drawbacks: - they are not very thermally stable, that is to say that their operating temperature must be less than 90 ° C, - and they have temperatures of relatively low glass transition (T _g ), ie of the order of 115 ° C.

However, in the technical field of the invention, it is necessary that the base materials used withstand high temperatures (at least

250 ° C), which are those which intervene during the manufacturing operations, e. g welding, optical devices. And as soon as they have this ability, they withstand, de facto, lower temperatures, which are encountered in the context of applications of such devices (150 ° C. maximum).

In an attempt to satisfy these thermal constraints, polyimides have been proposed recently which prove to be thermally stable up to 350 ° C., but the evaluation of which, as materials constituting optical guides, has made it possible to put highlight a major insufficiency with regard to the application properties Indeed, it appeared that the attenuation of the light which they induce is particularly important when they have been cooked at temperatures above 300 ° C.

This high attenuation is attributed to the scattering of light caused by organized or crystalline domains present within polymers (cf. H. F ANKE in "Polymers for lightwave and integrated optics"; Horna, Ed.; Marcel Dekker, Inc. : NY, 1992, p. 207). Another factor responsible for the attenuation of light is the absorption due to the harmonics of vibrations (υ of elongations and the combinations of vibrations of elongations and deformations (δ). The annoying absorptions for optical transmission at lengths of 1,320 and 1,550 nm are mainly from OH, NH (υ ₂ ) and aliphatic CH (υ ₂ + δ) bonds. It is therefore preferable to reduce the concentration of these bonds in the polymer for applications at 1,320 or 1,550 nm.

To do this, it has been proposed to replace the CH bonds by CD or CF bonds, which has the effect of shifting the relatively intense absorptions (υ _n , n = 2.3) towards the longer wavelengths. However, deuteration is difficult and expensive from the point of view of polymer synthesis. In addition, for the transmission at 1500 nm, it is not very effective because the elongation absorption band υ ₃ of the CD link is located around 1500 nm. Perfluorination would be more effective, but from a practical point of view, perfluorinated polymers are, for the most part, intractable and have poor adhesion. Another disadvantage of perfluorinated polymers lies in the fact that their refractive indices are rather low and it then becomes difficult to find an appropriate polymer (of index of even lower refraction) to form the sheaths of the fibers or confinement layers of the optical guides.

In a technical field totally different and distant from that of the present invention, thermostable polyester resins (70-220 ° C.) are known from patent FR 1 549 210. These resins have satisfactory dielectric properties and are therefore susceptible to a large number of applications in the electrical industries. They are obtained by condensation of dicarboxylic acids, their anhydrides or their chlorides (maleic acid, phthalic acid) with dialcohols with aromatic rings, in particular of the 2,2'-di (oxyalcohol) l, l'-dinaphthyle type, possibly chlorinated. It does not appear from this document that these chiral dioxydinaphthyls are used in the form of mixtures of enantiomers and even less in the form of racemates. The teaching provided by this previous reference has nothing to do with applications as optical guides in optoelectronics. The dielectric properties of these polyesters in no way prejudge their ability to guide.

US Patent 3,503,779 relates to aromatic polyesters for wavelengths outside the ultraviolet region. They are thus used as UV filters. These polyesters are synthesized from aromatic dialcohols and dicarboxylic acids, in particular of the dinaphthyl type. This patent in no way alludes to the use of chiral dinaphthyes for the manufacture of guides.

SHUKLA et al. in the article "Note synthesis of some novel polyamides" published in J. Macromol. Sci.-Chem., A24 (6), p. 701-706 (1987) describes polyamides whose recurrent unit comprises l, l'-binaphthyls branched by their positions 2,2 '. These aromatic polyamides are thermally stable. SHUKLA does not mention the use of mixtures and even less of the racemics of the chiral binaphthyes which he describes. The application in light guidance / transmission is not disclosed by this article.

Similarly, TAMAI et al. in the article "Synthesis of optically active polyamides having axially dissymmetric ..." published in Bull. Chem. Soc. Jpn., 64, 2260-2265 (1991), vol. 64, no. 7, describe polyamides comprising 1,1'-binaphthalene branched in 2-2 ', being in mono-enantiomeric form, in view applications in optical resolution.

TANAKA et al. in "Polyurethanes containing binaphthyl groups" published in Makromol. Chem. 185, 1915-1920 (1984) describes polyurethanes including binaphthyls unsubstituted in the 2-2 'position and characterized by a crystalline or semi-crystalline structure. It is clear that these polymers have nothing to do with optical materials capable of transmitting and guiding light, while being thermally stable and without giving rise to attenuation or absorption phenomena. Patent application EP 0454590 discloses optical guides produced from polyimides comprising chiral units of the biphenylene type connected to the polymer in 4-4 'and, moreover, only substituted in 2-2' positions.

Since the rotation of the two phenyls around the 1-1 'bond is easy in this configuration, this can lead to the presence of microcrystalline regions (cf. above: polyurethanes described by TANAKA et al). In this hypothesis, the performances in optical guidance are poor. It appears from this review of the prior art that there are no optical materials systematically having thermal and optical properties such that they can be used for the transmission and / or guiding of light in optical guides, such as waveguides, optical fibers, optoelectronic and / or optical integrated circuit connection elements or confinement layers.

In this situation, one of the essential objectives of the present invention is to provide a transparent optical material, which is not subject to high optical attenuation phenomena which are, of course, particularly troublesome in the context of transmission. or optical guidance. Another object of the invention is to provide optical materials which are thermally stable at high temperature and which have sufficiently high T _g .

SHORT STATEMENT OF THE INVENTION

It is to the credit of the Applicant to have highlighted that the amorphous polymeric materials with chiral patterns of particular structures carefully selected.

BEST WAY TO IMPLEMENT THE INVENTION:

The present invention thus relates to an optical material intended to be used for the manufacture of optical guides, characterized in that it consists of at least one polymer comprising chiral units (MC), selected from the following structures:

structure 1, 1 ′ -binaphthalene substituted at least in position 2,2 ′ by radicals different from hydrogen (structure I) or by homologs thereof:

Structure I

0 <m ≤ 2 and 0 ≤ p ≤ 4, and / or structure 1,1 '-biphenylene substituted in position 2,2' and 6,6 'by radicals different from hydrogen (structure II) or by homologs of these:

Structure II 0 < n < 3. L'une des particularités de telles molécules repose sur l'existence d'un blocage de la libre rotation des deux sous-ensembles aromatiques de ces molécules, autour de la liaison σ reliant C_x' à Cj. C'est donc à dessein que les substituants Z_λ et Zι de la structure I et Z_π et Z_π' et Y_π et Y_π' de la structure II diffèrent de l'hydrogène. Ils doivent avoir, avantageusement, un encombrement stérique tel qu'il empêche la rotation. Les propriétés optiques avantageuses de ce type de molécules sont, notamment, induites par leur non planéité.

Structure II 0 <n <3. One of the particularities of such molecules rests on the existence of a blockage of the free rotation of the two aromatic subsets of these molecules, around the bond σ connecting C _x 'to Cj. It is therefore on purpose that the substituents Z _λ and Zι of the structure I and Z _π and Z _π 'and Y _π and Y _π ' of the structure II differ from hydrogen. Advantageously, they must have steric hindrance such that it prevents rotation. The advantageous optical properties of this type of molecules are, in particular, induced by their non-flatness.

One of the possible solutions to block this rotation is to provide for the incorporation of MCs of structure I and II on the polymer, via Z _λ and Z, 'for structure I and Z _π and Z _π ' or Y _π and Y _π 'for structure II.

However, the invention is not however limited to this type of connection because, ultimately, it can take place via at least one, preferably two, positions chosen from the following list: ZZ , 'and X for the structure I and in the list: Z _π , Z _π ', Y _π , Y _π 'and X for the structure I

The preferred configuration of the invention is that in which the connections are made in position Z: Z „Zj ', for the structure I and Z _π , Z _π ' for the structure II. Advantageously, the connection of the MCs of structure I or II to the polymer is made directly by σ bond or by means of a spacer radical, chosen from alkylene, arylene, aralkylene, cycloalkylene or cycloaralkylene, substituted or not.

Since they do not participate in the connection of MC to the polymer, the substituents Z ,, Z, Z _π , Z _π ', Y _π , Y _π ' and X are identical or different between them and are, advantageously, selected among the following compounds: halogens, alkyls, aryls, alkoxyls, as well as the perhalogenated correspondents of these last three families of compounds and, preferably, from the following list: Cl, Br, F, C alkyl _! to C ₆ , phenyl, CF ₃ , OCH ₃ , O-CH ₂ -CH ₃ , O-phenyl. Within the meaning of the invention, the term "polymer" denotes, indifferently, homopolymers or copolymer mothers, whatever their degree of polymerization. According to a preferred characteristic of the invention, the MC chiral units are in the form of a mixture of enantiomers.

In accordance with the invention, preference is given to mixtures of MC chiral units of at least two R, S enantiomers, preferably present in respective proportions varying from 30-70 to 70-30 parts by weight and, more preferably still, from about 50-50 parts by weight, so as to form a racemic.

In practice and advantageously, these two enantiomers are two enantiomers are distributed statistically in the polymer chain.

Quite surprisingly and unexpectedly, the introduction of MCs in the form of mixtures of the two enantiomers into the main chain of the polymer leads to materials which do not have a crystalline phase in the solid state.

Indeed, it is only after numerous tests and researches that the Applicant has been able to note, in a non-obvious approach, the adequacy between these polymers, preferably statistical, and the optical applications in transmission and guidance of light. .

The amorphous polymers constituting the materials according to the invention are advantageously random copolymers.

It should be emphasized that these materials induce only very low optical attenuations in a wide range of wavelengths. Furthermore, the materials according to the invention have another advantage from the optical point of view which is that of a relatively weak residual birefringence on thin film.

Among their other interesting properties, we can recall:

- their high T _g , - their high thermal stability,

- Their solubility and their good ability to adhere to various substrates, in particular glass, silicon, metals and many polymers.

To detail a little more the interesting and preferred features of the materials according to the invention, it can be specified that at least part of the repeating units of the polymer comprises chiral units (MC), distributed at a rate ^ at least one ( MC) per recurring unit. In a preferred embodiment of the invention, the amorphous optical polymers are obtained by copolymerization of MC and another suitable comonomer. In this case, each repeating unit of the polymer comprises at least one MC. This advantageous method of the invention, in accordance with which MCs of aromatic nature are selected, results in an overall decrease in the concentration of CH bonds per unit volume. This contributes to making the optical material even less absorbent and therefore less subject to light attenuation phenomena by diffusion. In addition, the presence of these MC units in the polymer results in a significant increase in their solubility. These are, as we have seen above, important advantages in the field of optical light transmission and guidance.

The chiral units referred to above can be included in a linear and / or branched and / or curable or thermoplastic homopolymer or copolymer.

Advantageously, this polymer comprises at least one of the following polymerization functions: ester, esterimide, imide, amide, amide-acid, ether, carbon-carbon, siloxane, urethane, imidazole, carbonate, ketone, the ester, esterimide functions and imide being particularly preferred. Thus, this polymer can be, for example, a polyester, a polyesterimide, a polyamide, a polyamidacid, a polyimide, a polyurethane, a polyesterbenzimidazole, a polycarbonate, a polyether, a polyetherketone or a polysiloxane. In practice, a polyester, a polyesterimide or a polyimide, advantageously of an aromatic nature, is preferably chosen as the constituent polymer of the optical material according to the invention.

According to an advantageous embodiment of the invention, the molecular weight of the polymer is between 1,000 and 500,000 daltons and, preferably, between 1,000 and 100,000 daltons.

dans laquelle :The linear (thermoplastic) homopolyesters according to the invention can be formed by repeating units having the general structure shown below:

in which :

- n »≥ 1,

- R * corresponding to the structure I or II described above,

- E is the ester function (COO or OCO),

- and F is chosen from the following reasons:

avec 0 ≤ n ≤ 4 et W sélectionné parmi les halogènes, les aryles, les alkyles ou les alcoxyles C, à C₆, éventuellement perhalogenes, de préférence parmi les composés suivants : F, Cl, Br, CF₃, CH₃, Ph, OCH₃, où :

with 0 ≤ n ≤ 4 and W selected from halogens, aryls, alkyls or alkoxyls C, to C ₆ , optionally perhalogenic, preferably from the following compounds: F, Cl, Br, CF ₃ , CH ₃ , Ph , OCH ₃ , where:

where R ¹ is selected from the following list: O, S, CO, SO ₂ , CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ , C (CF ₃ ) (Ph), P (O) Ph or a direct σ bond.

Among the other polymers suitable according to the invention, mention may be made of homopolyesterimides of a repeating unit having the following structure:

dans laquelle :

in which :

- n ;,> 1,

- R * corresponds to the structure I or II described above,

- E is the ester function (COO or OCO),

- and I, is a motif containing at least one imide function, preferably one or two, Ij being, advantageously, formed by at least one of the following radicals

wherein :

n = 0 à 4 et W = halogènes, alkyles ou alcoxyles de C, à C₆, éventuellement perhalogenes, de préférence = OCH₃, Ph, CF₃, CH₃ F, Cl, ou Br ou aliphatique. - R³, R^s et R⁶ sont identiques ou différents et répondent à la même définition que- R ² =

n = 0 to 4 and W = halogens, alkyls or alkoxyls from C to C ₆ , optionally perhalogenic, preferably = OCH ₃ , Ph, CF ₃ , CH ₃ F, Cl, or Br or aliphatic. - R ³ , R ^s and R ⁶ are identical or different and correspond to the same definition as

R ² ,

- R * = ar le, preferably:

R ⁷ corresponding to the same definition above as R ¹ or R ² .

A final example of preferred polymers is given by homopolyimides of a recurring unit having the general structure:

in which :

- R * corresponds to the structure I or II described above,

- and I ₂ is a motif containing at least one imide function and, preferably, constituted by a general structure pattern

dans laquelle :

in which :

- R ³ , R ⁴ and R ^s are as defined above where R ³ and R ^s can also be a direct bond.

According to the invention, it is possible to fine-tune the physical properties such as Tg, refractive index, birefringence, adhesion or solubility. To do this, the invention provides copolymers involving two or more different repeating subunits. Advantageously, these copolymers can be characterized by the repeating unit below represented:

^{R '^→> H ^R ' ^{→ G} - ^} l J n _e > l or:

- a + b + c = 1,

- a + b> 0,

- c varies between 0 and 0.8,

- H „H ₂ and H ₃ are comonomers of ester (EFE) or esterimide (EI, -E) or imide type Or described above,

- G is an alkyl or aromatic group.

The above polyesters and polyesterimides can be synthesized according to the conventional esterification routes from a dialcohol or dialcoholate and an esterifiable dicarboxylated derivative (XCORCOX with X = OH, Cl, Br, F, OMe, OEt, OPh ...) , especially under biphasic conditions, in the presence of a phase transfer catalyst, in solution in an organic solvent or in bulk. For the synthesis of polyester or polyesterimide, one can consult for example the articles of OISCHI et al., J. Polym. Sci. Polym. Chem., Ed 1989, 27, 1425, of LIOU et al J. Polym. Sci. Part A, Polym. Chem., 1992, 30, 2195 and GB patent 1 027360.

The polyimides and polyesterimides can be synthesized by reacting a diamine with a dianhydride. This reaction takes place in two stages: in a first stage, a polyamide-acid is obtained and then the amide-acid functions are cyclized in solution or in the pure state in bulk at high temperature. These syntheses are conventional and are described for example in US patents 3,356,648 and 3,179,634. Note that two ways can be used for the synthesis of a polyesterimide: the condensation takes place either by formation of the ester function, or by formation of the imide function. In all these syntheses, the MCs can constitute all or part of the comonomers used.

For some applications, it may be desirable to have an optical material which can be made insoluble. Such a property, e. g., in fact facilitates the deposition of several layers of polymers and also allows the drawing of guides by lithography, then the washing of the non-crosslinked part.

To this end, the invention also relates to optical materials made of polymers, copolymers or oligomers, of the type described above and modified by the incorporation of reactive or crosslinkable functions in the main chains, coaxially or pendant laterally, or else at the end of the chains. The crosslinkable groups are chosen from reactive groups comprising a double bond and / or a triple bond (CC, CN) and / or a cycle of the cyclobutene, epoxy, and / or OH and / or COW type ("W" = Cl, Br, F, OMe, OPh, OH) and their derivatives, preferably from those listed below: maleimide, nadimide, acrylic, methacrylic, acrylamide, alcohol, amino, carboxylic, vinyl, styryl, allyl, silyl, cyanate, isocyanate , thiocyanate, cyanamide, nitrile, epoxy, acetylene, olefinic, benzocyclobutene or their derivatives.

Crosslinking leading to insolubility can be carried out by heat, photochemical treatment, electron beam or any other technique known to those skilled in the art. It is sometimes useful to use a crosslinking aid, preferably unsaturated, connecting at least two reactive functions. As examples of auxiliary crosslinking include: ethylene glycoldiacrylate, divinylbenzene, phenyldiisocyanate, dimaleimidophenyl-methane, pentaerythritoltriacrylate, tris (2-acryloxyethyl) isocyanurate, hexamethylenediisocyanate, a polyol or a tris. The present invention also relates to optical materials comprising the polymers defined above, which are in crosslinked form.

According to another characteristic of the invention, the optical material considered has an optical attenuation between 400 and 2,000 nm less than or equal to 1 dB / cm, preferably 0.5 dB / cm and, more preferably still, 0, 4 dB / cm.

Taking into account all the qualities set out above, the optical material according to the invention proves to be particularly suitable for being applied as a material constituting optical devices, in particular of the type of fibers or optical guides, confinement layers or organs of interconnection in an optical or optoelectronic integrated circuit.

The present invention also relates to the above optical devices.

The invention will be better understood, its advantages and variants of implementation will emerge clearly from the examples which follow which describe the synthesis and the characteristics of seven optical polymeric materials PI, P2, P1 / P2, P3 to P6 in accordance with the invention .

EXAMPLES

In all these examples, the optical characterization of the polymer obtained is carried out. This is done as shown below.

The index and the thickness of the polymer deposited on a glass substrate, by the so-called "spin coating" method are obtained by the method of coupling the modes of a light beam on a Metricon 2010 device. The optical losses are obtained by the method of scattered light coupled into the 1.5 to 5 μm flat film or by the sliding prism method. These techniques are described in the articles of WEBER et al., Appl. Opt., 1973, 12, 755 and de FRANKE et al., SPIE, vol 682, 1986, 191.

EXAMPLE 1: SYNTHESIS OF A POLYESTER (PI).

(PI)

5.44 g (26.8 mmol) of terephthaloyl chloride dissolved in 40 ml of 1,2-dichloroethane are added to an aqueous solution containing 26 mmol of (±) - sodium binaphtholate prepared from NaOH (1 molar) and (±) -binaphthol and 250 mg of benzyltriethylammoniun chloride. The two-phase mixture is stirred vigorously for one hour at 60 ° C. The polymer formed is recovered by precipitation in methanol, then filtered. After drying, a white polymer is obtained with 87% yield. The polymer is purified by dissolution in chloroform, followed by precipitation in methanol.

Molecular mass by weight (Mw) (polystyrene equivalent) = 35,000, Tg = 204 'C, the mass loss temperature measured in ThermoGravimetric Analysis (ATG) (-10%) = 480 ^e C, refractive index at 633 nm = 1.67 and the optical attenuation:

- at 633 nm = 0.40 dB / cm, - at 815 nm = 0.15 dB / cm,

- at 1300 nm = 0.20 dB / cm.

The birefringence of PI is 0.008. EXAMPLE 2: SYNTHESIS OF A POLYESTER (P2).

(P2)

9.60 g (34.9 mmol) of tetrafluoroterephthaloyl chloride dissolved in 50 ml of 1,2-dichloroethane are added to an aqueous solution containing 34.9 mmol of sodium (±) -binaphtholate prepared as in Example 1 and 200. mg of benzyltriethylammonium chloride. The mixture is vigorously stirred for 1 hour at 50 ° C., then poured into 600 ml of methanol. The polymer is recovered by filtration, washed with methanol, then dried under vacuum at 50 ° C for 12 h. 15.0 g of polymer are obtained.

Mw (polystyrene equivalent) = 16,000, Tg = 197 ° C, the mass loss temperature measured in ATG (-10%) = 460 ° C, refractive index at 633 nm = 1.63 and the optical attenuation at 815 nm and 1300 is 0.2 dB / cm. Birefringence = 0.003.

EXAMPLE 3: SYNTHESIS OF A COPOLYESTER (P1 / P2).

(P1 / P2) A copolyester is synthesized, as described in the previous examples, from binaphthol and a 50/50 mixture of teréphthaloyl chloride and tetrafluoroterephthaloyl chloride. The polymer has properties similar to PI and P2, but with a refractive index at 633 nm of 1.65, intermediate between those of the two homopolymers.

EXAMPLE 4 SYNTHESIS OF A POLYESTER (P3).

(P3)

To a mixture containing 7.87 g (18.34 mmol) of 4,4'dicarboxyphenyl-1 dichloride, hexafluoroisopropylidene, 5.25 g (18.34 mmol) of binaphthol and 25 ml of o-dichlorobenzene are added slowly and, in portions, 3.5 ml of pyridine at room temperature, under nitrogen and with stirring. The mixture is then heated at 150 ° C for 8 hours. The viscous solution is diluted with 20 ml of dichloromethane, then the polymer is recovered by precipitation in 600 ml of ethanol, followed by filtration and drying. Yield = 10g (85%). Mw (polystyrene equivalent) = 25,000, Tg = 211 ° C, the mass loss temperature measured in ATG (-10%) = 490 ° C, refractive index at 633 nm = 1.60 and the optical attenuation: - at 633 nm = 0.10 dB / cm,

- at 815 nm = 0.05 dB / cm,

- at 1300 nm = 0.20 dB / cm. Birrefringence of P3 = 0.004. EXAMPLE 5 SYNTHESIS OF A POLYESTERIMIDE (P4).

The polyesterimide P4 is synthesized according to the following reaction scheme.

^C0C1

D

(P4)

The acid dichloride D1 is synthesized by reaction of the fluorinated dianhydride with two equivalents of p-aminobenzoic acid in acetic acid under reflux, followed by a reaction with an excess of thionyl chloride. The polymer is synthesized as described in Example 4. Mw = 53,000 (polystyrene equivalent), Tg = 265 ° C, the mass loss temperature measured in ATG (-10%) = 475 ° C, refractive index at 633 nm = 1.63 and optical attenuation = 0.3 dB / cm at 1300 nm. Birefringence = 0.023. EXAMPLE 6 SYNTHESIS OF A CROSSLINKABLE POLYESTERIMIDE (PS).

It is polyesterimide P4 modified by placing acrylate functions at the end of the chains. It is synthesized using an excess of binaphthol with respect to the acid dichloride and terminal OH functions are reacted with acryloyl chloride.

<P5)

A mixture containing 7.50 g of binapthol, 12.50 g of Dl (example 5), 1.58 g of acryloyl chloride and 70 ml of o-dichlorobenzene is cooled to 0 ° C. and 7.3 is added thereto. ml of triethylamine. The mixture is then brought to 50 ° C. for 2 hours 30 minutes. The polymer is recovered by precipitation in ethanol, then filtered and dried under vacuum for 48 hours at room temperature. Mw = 4,400 (polystyrene equivalent). The polymer, in solution in dimethylacetamide (30% by mass), is filmed on glass by spin-coating, then subjected to a heat treatment of 280 ° C for 1 hour under vacuum. The polymer is insoluble in various solvents, such as tetrahydrofuran, dimethylacetamide and chloroform and has an optical attenuation:

- at 633 nm = 0.40 dB / cm,

- at 815 nm = 0.20 dB / cm,

- at 1300 nm = 0.25 dB / cm. Birefringence of P5 = 0.002.

EXAMPLE 7: THERMAL STABILITY OF THE POLYMERS OF EXAMPLES 1 TO 6.

Each polymer (PI, P2, P1 / P2, P3, P4, P5) is placed on a glass substrate, which is then heated under vacuum at 200 ° C for 4 hours, then 2 hours at

280 ° C. The measurement of the optical attenuation, after the treatment at 200 ° C and the treatment at 280 ° C, shows that there is no significant difference between the film subjected to a heat treatment at 200 ° C and the film heated to 280 ° C, for each of the polymers tested.

EXAMPLE 8 SYNTHESIS OF A POLYIMIDE (P6).

(P6)

Polyimide P6 is synthesized in two stages. In a first step, the fluorinated dianhydride is reacted with an equivalent of binaphthyldiamine in N-methylpyrolidone (% by weight of polymer = 16%), for 48 hours, at room temperature and with stirring. The polyamide-acid thus formed (Mw = 26,000 (polystyrene equivalent)) is filmed on glass by spin-coating. In a second step, the polyamide is converted to polyimide by a heat treatment of one hour at 100 ° C, 1 hour at 200 ° C and, finally, 1 hour at 300 ° C. The Tg of the polymer is around 310 ° C, the ATG mass loss temperature (-10%) is 525 ° C and the optical attenuation is 0.25 dB / cm at 1300 nm. The preferred optical materials according to the invention are those chosen from the list comprising:

* the (co) polymers defined by the recurring units PI, P2, P1 / P2, P3, P4, P5, P6 presented above in the examples;

* the copolymers formed by at least two of the recurring units referred to above (PI, P2, P1 / P2, P3, P4, P5, P6),

* and mixtures of these (co) polymers and copolymers.

Claims

CLAIMS: 1 - Optical material intended to be used for the manufacture of optical guides, characterized: - in that it is constituted by at least one polymer comprising chiral units (MC), selected from the following structures: . l,l'-binaphthalene structure substituted at least in the 2,2' position by radicals other than hydrogen (structure I) or by homologs thereof:

Structure I O ≤ m < 2, 0 < p ≤ 4, and/or structure 1,1'-biphenylene, substituted in positions 2,2' and 6,6' by radicals other than hydrogen (structure II) or by counterparts of these:

Structure II 0 < n ≤ 3, - in that the connection of MC (I or II) to the polymer takes place via at least one, preferably two, positions chosen from the following list: Z _I? Z _r ' and X for structure I and in the following list: Z _π , Z _π ', Y _π , Y _π ' and - and in that, in the case where they do not participate in the connection of MC to the polymer, the Z _I? Zj', Z _π , Z _π ', Y _π , Y _π ' and of compounds and, preferably, from the following list: Cl, Br, F, Cj to C ₆ alkyl, phenyl, CF ₃ , OCH ₃ , O-CH ₂ -CH ₃ , O-phenyl. 2 - Optical material according to claim 1, characterized in that the connection of the MCs of structure I or II to the polymer is done directly by a bond or via a spacing radical, chosen from alkylenes, arylenes, aralkylenes, cycloalkylenes or cycloaralkylenes, substituted or not. 3 - Optical material according to claim 1, characterized in that the chiral patterns (MC) are in the form of a mixture of enantiomers. 4 - Optical material according to claim 3, characterized in that the chiral patterns (MC) are formed by a mixture of at least two enantiomers R, S, preferably present in respective proportions varying from 30-70 to 70-30 parts by weight and, more preferably still, of the order of 50-50 parts by weight, so as to form a racemic, the two enantiomers being, preferably, distributed randomly in the polymer. 5 - Optical material according to claim 1, characterized in that at least part of the recurring units of the polymer comprises chiral units (MC) distributed at least one (MC) per recurring unit. 6 - Optical material according to claim 1, characterized in that each repeating unit of the polymer comprises at least one MC. 7 - Optical material according to claims 1, characterized in that the polymer comprises at least one of the following polymerization functions: ester, esterimide, imide, amide, amide-acid, ether, carbon-carbon, siloxane, urethane, imidazole , carbonate, ketone, the ester, esterimide and imide functions being particularly preferred. 8 - Optical material according to claim 1, characterized in that the polymer contains reactive functions placed in the main chains, coaxially or laterally pendant, and/or on at least one of the ends of said chains, these reactive functions being capable of crosslinking, possibly in the presence of a crosslinking auxiliary, to give an insoluble polymer. 9 - Optical material according to claim 1, characterized in that the molecular mass of the polymer is between 1,000 and 500,000 daltons and, preferably, between 1,000 and 100,000 daltons. 10 - Optical material according to claim 1, characterized in that it has an optical attenuation between 400 and 2,000 nm, less than or equal to 1 dB/cmj preferably 0.5 dB/cm and, even more preferably, at 0.4dB/cm. 11 - Optical material according to claim 1, characterized in that it is chosen from the list comprising: * (co)polymers defined by the recurring units of the following general formulas:

(IP)

(P2)

(P1/P2) L

(P3) L

25 (P4)

30 (P5)

(P6) * copolymers formed by at least two of the recurring units referred to above (PI, P2, P1/P2, P3, P4, P5, P6), * and mixtures of these (co)polymers and copolymers. 12 - Application of the material according to claim 1 in optics and, in particular, as a constituent material of optical guides, in particular of the waveguide type, optical fibers, confinement layers or interconnection members in an optical or optoelectronic integrated circuit . 13 - Optical guides according to claim 12.