EP0473743A1

EP0473743A1 - Compositions active in non linear optics, materials and systems containing them

Info

Publication number: EP0473743A1
Application number: EP19910905120
Authority: EP
Inventors: Yves Camberlin; Rémi Meyrueix; Gérard Mignani
Original assignee: Rhone Poulenc Chimie SA; Flamel Technologies SA
Current assignee: Flamel Technologies SA
Priority date: 1990-02-26
Filing date: 1991-02-25
Publication date: 1992-03-11
Also published as: WO1991013116A1; FR2658826B1; JPH04505474A; FR2658826A1

Abstract

La présente invention a pour objet des matériaux présentant une activité en optique non linéaire et des dispositifs les contenant. Ces compositions sont du type comprenant une matrice formée à base de polymère(s) et au moins un composé hyperpolarisable dont le constituant principal de la matrice est un polymère thermodurcissable à groupe imide, de préférence à groupe maléimides.The subject of the present invention is materials having activity in nonlinear optics and devices containing them. These compositions are of the type comprising a matrix formed on the basis of polymer (s) and at least one hyperpolarisable compound whose main constituent of the matrix is a thermosetting polymer with imide group, preferably with maleimide group.

Description

NON-LINEAR OPTICAL ACTIVE COMPOSITIONS, MATERIALS AND DEVICES CONTAINING THEM

The present invention relates to materials having activity in nonlinear optics and to devices containing them.

It relates more particularly to materials of the type comprising a matrix constituted by a polymer in which a hyperpolarizable compound is incorporated.

Many optical or electro-optical devices, such as switches, modulators, directional couplers, bistables use the property of certain materials to be active in non-linear optics. Thus, the devices use as an active element in nonlinear optics inorganic crystalline compounds such as LiNbθ3, hydrogenophosphates such as (KDP, ADP, TP) or organic compounds. These organic compounds can be single crystals, ordered molecular layers of the Lang uir Blodgett type, active polymers. In the latter, the activity in non-linear optics is generally provided by a hyperpolarisable compound ordered non-centro-symmetrically in a polymerizable matrix. There are two classes in active poly erized materials: functionalized polymers in which the hyperpolarisable compounds are grafted by covalent bond on the polymer backbone; and

- Materials in which the hyperpolarizable compound is incorporated, for example by dissolution, in the polymerizable or polymerized matrix. These latter materials are sometimes called "Guest / host" materials. By way of example of a hyperpolarizable compound, mention may be made of the "Disperse Red One" sold by the company Aldrich under the name "DR1". European patent N ^β 218938 describes such a material and cites numerous hyperpolarisable organic compounds and polymers compatible to form the matrix. Thus, the polymers mentioned are acrylates, ethacrylates, transparent epoxies, styrene or polycarbonates. The material is activated by orientation of the hyperpolarizable compounds under the effect of an electric, electromagnetic or magnetic field. The polymer generally used is polymethyl methacrylate (PMMA). However, the matrix is a material whose rigidity is imperfect ^¬ made, variable according to the temperature and only preventing incomplete movements of the contained compounds, which will tend to be disoriented, in other words to return to a position d balance of the dipoles in the material.

This disorientation has of course, as a consequence an often erratic decrease in the activity in nonlinear optics.

This phenomenon is all the more important as the compound, where the hyperpolarizable molecule is freer vis-à-vis the matrix; thus the disorientation is faster when the molecule is attached to the polymeric skeleton by means of a spacer arm and this all the more that the arm will be long. A fortiori the effect is extreme when the molecule. active in ONL is not chemically linked to the skeleton and is therefore formed only of a host molecule "dissolved" in a polymer matrix chemically independent of said host molecule.

In addition, the above materials have certain drawbacks. Indeed, the hyperpolarizable matrices and compounds must be miscible. More particularly, especially in the case where the active molecule in ONL is not chemically linked to the skeleton, the hyperpolarizable compound must have the greatest possible solubility in the matrix polymer and in common solvents so as to obtain the optical activity the as high as possible.

An object of the present invention is to provide a polymer matrix which avoids disorientation phenomena in all cases.

An object of the present invention is to provide a polymeric matrix which avoids disorientation phenomena even when the molecule is attached to the polymeric backbone by means of a spacer arm even long.

An object of the present invention is to provide a polymer matrix which avoids disorientation phenomena even in the case where the molecule active in ONL is not chemically linked to the skeleton and is only formed from a host molecule "dissolved" in a polymer matrix chemically independent of said host molecule.

These aims and others which will appear subsequently are achieved by means of a new material of the type comprising a matrix based on polymer (s) and at least one hyperpolarizable compound, exhibiting a higher activity in nonlinear optics due mainly to a better solubility of the hyperpolarizable compound and to a reduction in the loss of activity over time. To this end, the invention provides a material of the type comprising a matrix formed on the basis of polymer (s) and at least one hyperpolariable compound characterized in that the main constituent of the matrix is a thermosetting polymer with i ide groups. .

This polymer makes it possible to substantially increase the solubility of hyperpolarizable compounds, and in particular, by way of example, those which contain cyano radicals in their molecule, nitro- radicals.

Thus, the activity in non-linear optics of these materials is significantly higher than that of materials produced with other polymers as matrix, such as polymethyl methacrylate. In addition, the concentration of hyperpolarisable compound or motif will be as high as possible, its upper limit being limited by the compatibility, or solubility, of the compound in the polymer (that is to say a formation of a second phase This limit is further pushed back when the hyperpolarisable compound is attached to the chain. Advantageously, the concentration of hyperpolarizable compound is approximately 1 to 20% by mass.

Another advantage of the material of the invention lies in the exceptional stability of the activity in non-linear optics as a function of time. In particular, the disorientation phenomena are not very marked in the case where the active molecule in ONL is not chemically linked to the skeleton and is only formed from a "dissolved" host molecule (in the sense of a solid solution) in a polymer matrix chemically independent of the said host molecule, a fortiori when the ONL units are connected to the polymer backbone with or without a spacer arm. Indeed, it has been found that the phenomenon of disorientation of the active groupings in linear optics were significantly slower than in the so-called "guest / host" systems.

Besides, their very great stability over time, the polymers according to the invention have the advantage of being very film-forming.

The best results are obtained using as polymer those obtained by a reaction, at a temperature ranging from 50 ° C to 180 ° C, between:

- (a) one or more bis-maleimide (s) corresponding to formula (I) and to the definitions given above with regard to this formula,

an N, N '-Bis-imide of formula Y

R-C = CH-CO- N (R ') A - N (R') - CO - CH = CR (I)

in which: the radicals R independently represent a hydrogen atom or alkyl or alkylidene radicals of low molecular weight (from 1 to Cς,) optionally substituted.

R 'independently represents an acyl group of Ci to CQ optionally substituted or an acylidene group of Ci to CQ, optionally substituted and / or unsaturated. R and R 'being advantageously linked together to form a heterocycle of 5 to 7 links;

A is cited below.

Preferably the radicals R and R 'are chosen so that the formula (I) becomes the formula (I')

Y in which :

. the symbols Y independently represent H, CH3 or Cl; . the symbol A represents a divalent radical preferably chosen from the group consisting of the radicals: cyclohexylenes; phenylenes; 4-methyl-1,3-phenylene; 2-methyl-1,3-phenylene; 5-methyl-1,3-phenylene; 6-methyl-1,3-phenylene; 2,5-diethyl-3-methyl-1,4-phenylene; and the radicals of formula:

in which T represents a simple valential link or a grouping:

and X represents a hydrogen atom, an ethyl, ethyl or isopropyl radical; - one (or more) reagent (s) (b) and / or (c);

(b) consisting of one or more heterocyl (s) substituted in particular by unsaturated short chains (C2-C6) such as: vinylpyridines, N-vinylpyrrolidone-2, 1 allyl isocyanurate, vinyltetrahydrofuran; (c) consisting of a compound of the styrene type, such as for example V α -methyl-styrene, divinyl benzene or 1-ethyl-vinyl-benzene.

The ratio (b + c) / a can vary from 1/20, preferably from 1/10, to 1.

- and if necessary to improve the rheology one or more acrylate reagents (d) consisting of one or more compound (s) of general formula:

(CH2 = CRÔ - CO - 0 r (II)

in which :

. the symbol R5 represents a hydrogen atom or a methyl radical;

. n represents an integer or fractional number at least equal to 1 and at most equal to 8;

. the symbol B represents an organic radical of valence n derived: from a saturated, linear or branched aliphatic residue, having from 1 to 30 carbon atoms and which may contain one or more oxygen bridge (s) and / or one or more function ( s) free hydroxyl (s); an aromatic residue (of aryl or arylaliphatic type) having from 6 to 150 carbon atoms consisting of a benzene ring, which may be substituted by one or three al yl radicals having from 1 to 5 carbon atoms, or by several benzene rings , optionally substituted as indicated above, linked together by a simple valential bond, an inert group or an alkylene radical having from 1 to 3 carbon atoms, said aromatic residue being able to contain at various places in its structure one or more bridges ( s) oxygen and / or one or more free hydroxyl function (s), the free valence (s) of the aromatic radical B being able to be carried by a carbon atom of an aliphatic chain and / or by a carbon atom of a benzene ring. The amount of reagent being such that the mas d / a ratio can vary from 0 to 1/10.

Optionally:

. one or more monomers of formula III, IV, V

in which the allyloxy or methallyloxy radical is in the ortho, metha or para position relative to the carbon atom of the benzene ring linked to nitrogen;

(IV)

In the above-mentioned compound, the proportions of the various constituents for mixing the products of formulas (III) (IV), and possibly (V) can vary within wide limits.

As specific examples of bis-imides (a) of formula (I), o may in particular mention the compounds indicated in French application 85/17918, that is to say:

- N, N'-metaphenylene-bis-maleimide,

- N, N'-paraphenylene-bis-maleimide,

- N, N'-4,4 '-diphenylmethane-bis-maleimide,

- N, N'-4,4 '-diphenylether-bis-maleimide,

- N, N'-4,4 '- diphenylsulphone-bis-maleimide,

- N, N'-cyclohexylene-1,4-bis-maleimide,

- N, N'-4,4'-diphenyl-l, l cyclohexane-bis-maleimide,

- N, N '-4,4'-2,2-diphenyl-propane-bis-maleimides,

- N, N '-4,4' -triphenylmethane-bis-malei ide,

- N, N '-methyl-2 phenylene-1,3-bis-maleimide,

- N, N '-methyl-4 phenylene-1,3-bis-maleimide,

- N, N '-methyl -5 phenylene-1,3-bis-maleimide.

These bis-mal eimides can be prepared according to the methods described in the American patent US-A-3,018,290 and the Angla patent GB-A-1,137,290. Preferably, for the implementation of the present invention, N, N'-4,4 '-diphenylmethane-bis-maleimide taken alone or as a mixture with N, N' -methyl-2-phenylene-1,3-bis-maleimide, N, N '- 4-methylphenylene-1,3-bis-maleimide and / or N, N'-methyl-5-phenylene-1,3-bis-maleimide.

As suitable acrylate reagent (d), there may be mentioned: (dl) the mono (meth) acrylates corresponding to formula (II) in which:

n - *** 1, and

B represents a monovalent organic radical of formula:

- (CH ₂ CH2θ) _m Bi (VI)

in which: Bi represents an alkyl radical, linear or branched, having from 1 to 6 carbon atoms or a phenyl radical; and m is an integer equal to zero, 1 to 9

(d2) the di (meth) acrylates corresponding to formula (IV) in which:

. n = 2, and

. B represents a divalent organic radical of formula:

- (CH2 CH2θ) _p B2 (OCH2 CH ₂ ) q (VII)

in which: B2 represents a divalent alkylene radical, linear or branched, having from 2 to 9 carbon atoms and which can contain one or more oxygen bridge (s) or a radical of form

in which the symbol U represents a simple valential link or a grouping: -CH2-, -CH2-CH2, -CH (CH3) CH2 -, -0-, -S-

CH3

the symbols p and q, identical or different, each represent an integer equal to zero, 1, 2, 3, 4 or 5;

(d3) the tri- and tetra (eth) acryl ates corresponding to the formula (VI) in which the:

. n = 3 or 4, and

. B represents a trivalent or tetravant organic radical derived from a saturated, linear or branched aliphatic residue, having from 3 to 20 carbon atoms and which can contain one or more oxygen bridge (s) and / or one or more function (s) ) free hydroxyl (s);

(d4) novolak epoxy (meth) acrylates which, while corresponding to formula (IV), are represented here by the following formula:

in which :

. the symbol R6 has the meaning given above in relation to formula (II); . the symbol Rπ represents a hydrogen atom or a methyl radical; . t is an integer or fractional number in the range from 0.1 to 7;

(d5) mixtures of several acrylates and / or methacrylates of the same type

[(dl), (d2), (d3) or (d4)] between them or mixtures of one or more acrylate (s) and / or methacrylate (s) of the same type with one or more acrylate (s) ) and / or methacrylate (s) of another type. As specific examples of acrylate reactant (dl) which convien ^¬ NENT well, there may be mentioned in particular: mono (meth) acrylates; mono (meth) acrylates of (mono-oxyethylated) phenol; (di-oxyethylated) phenol mono- (meth) acrylates. ^"As specific examples of acrylate reactant (d2) which convien ^¬ NENT well include: di (meth) acrylates of ethylene glycol, the di (met) acrylates of 1,4-butanediol, the di (meth ) 1,6-hexane-diaol acrylates; tripropylene glycol di (meth) acrylates; di (eth) acrylates of diphenols, di (mono-or poly-oxyethylated) or not, the following: 4,4-dihydroxy '-diphenylmethane, bisphenol A, dihydrocy-4,4' -diphenylether and in particular the di (meth) acrylates of bisphenol A di (mono-oxyethylated) or the di (meth) acrylates of bisphenol A di (di-oxyated ¬ thyle) [cf. formula (VII)

CH ₃

I in which B represents the radical: -C- and p = q = 1 or 2]

CH ₃

By way of specific examples of acrylate reagent (d3) which are suitable, there may be mentioned in particular: tri (meth) acrylates of 1,2,4 butanetriol; tri (meth) acrylates of hexanetriol-1,2,6; trimethylolpropane tri (meth) acrylates; pentaerythritol tri (meth) acrylates; pentaerythritol tetra (meth) acrylates.

Novolak epoxy (meth) acrylates (d4) are known products, some of which are commercially available. They can be prepared by reacting (meth) acrylic acids with a novolak type epoxy resin, the latter being the reaction product of epichlorohydrin and pheno / formaldehyde polycondensates in formula (VIII) given above Ru is then a hydrogen atom or cresol / formaldehyde polycon¬ densates in the formula Ru is then a methyl radical. These oligomeric polyacrylates (e4) and a process for preparing them are described for example in American patent US-A-3,535,403. By way of specific examples of acrylate reagent (e4) which are suitable, there may be mentioned in particular the novolak epoxy acrylates of formula (VIII) in which R6 and Rπ represent a hydrogen atom and t is a whole or fractional number in the range of 0.1 to 5.

By way of specific examples of acrylate reagent (e5) which are suitable, mention may be made of mixtures of (meth) acrylates of novo¬ lacquer epoxy (e4) with at most 30% by weight, relative to the weight of the mixture (e4) + (e3), of a triacrylate and / or of a trimethacrylate corresponding to the definitions given above with regard to the acrylate reagent (e3) and in particular the mixtures of novolak epoxy acrylates which are suitable, just mentioned above, with at most 25% by weight, relative to the weight of the mixture, of a triacrylate and / or a suitable trimethacrylate well chosen from those just mentioned above.

The acrylate reagent (e) which is used very preferably is taken from the group formed by: the di (meth) acrylates of bisphenol A di (mono-oxyethylated); novolak epoxy di (meth) acrylates of formula (VIII) in which R6 and Ru represent a hydrogen atom and t is an integer or fractional number lying in the range ranging from 0.1 to 5, these compounds being taken alone or as a mixture with at most 25% by weight, relative to the weight of the mixture, of trimethylolpropane triacrylate.

The acrylate reagent (e), formed from one or more compound (s) of formula (IV), is used in amounts generally representing from 1% to 60% and, preferably, from 5% to 30% of the total weight of the reagents (a) + (b) + possibly (c) + (e). Advantageously, the above polymers having a melt viscosity measured under the conditions defined below between 0.1 Pa.s and 500 Pa.s.

According to another characteristic of the invention, the hyperpolarizable compound is chosen from hyperpolarizable compounds comprising cyano and / or nitro radicals.

By way of example, suitable compounds can be:

- those described in the article by H.E. Katz et al published in Mol.

Cryst. Inc Non linear Opt. Flight. 157, p. 525-533 (1988) having the following formulas:

CN

- the "Disperse Red One" or "DRl" marketed by the company Aldri having as formula:

- those described in French patent application n ° 88 12028, forgotten under N ^β 2 636441 and having the general formula:

in which A and Ai represent electron acceptor groups D electron donor groups such as, for example, the following compound

This list is not exhaustive. In fact, any hyperpolarized compound soluble in the styrene / acrylonitrile copoly is suitable for the invention. Any non-centrosymmetric compound having at least one donor group and at least one acceptor group linked together with an at least double bonding system (s), has more or less the property of being active in non-linear quadratic optics.

The material of the invention can be used in any form such as films, moldings, extrusions, etc.

It is also possible, without departing from the scope of the invention, to add different components or additives to the material to improve these mechanical or shaping properties, for example flame retardants, antistatics, antioxidants, similar stabilizers. The invention also relates to an optical or optoelectric device comprising at least one element made of the material according to the invention.

The thermoplastic material obtained is brought to a temperature higher or close to its glass transition temperature. A continuous electric field is applied to the film and directs the active molecules.

The material is then cooled to a temperature below its glass transition temperature (Tg) so as to freeze the oriented position of the active molecules. The process described above is given by way of example only and does not limit the invention in any way. Mention may also be made, by way of example of a method of manufacturing such materials, of European patent n ^β 218938.

It is also easily understandable that the material conforms to the desired form of use, preferably before carrying out the orientation of the molecules.

The activity of materials in nonlinear optics is determined by the measurement of second, third or umpteenth order susceptibilities.

The susceptibilities of a material are directly related to the polarization of the material by the following fundamental relationship: £ = Po + *. £ + ² D - + ^~ - ³ EEE +

in which: £ and Po represent the polarization respectively in the presence and absence of the electromagnetic field. E represents the electromagnetic field. 2C, χ2, ^ 3 represent the linear and non-linear susceptibilities of the material.

Preferably, the hyperpolarizable compound is dissolved in the copolymer in the molten state or in the state dissolved in a solvent.

The polymer is then heated to a temperature higher than its glass transition temperature (Tg), then subjected to an intense electric field to orient the hyperpolarizable molecules. This polarization can be carried out using electrodes deposited on either side of the film or by the well-known technique called "coronna" and for example described in the article by Martazavi M.A. et al. J. Opt. Soc. Am. B. Vol. 6 (4), 1989, p. 733.

Is generally used, ^"a following operating sequence, using both the good solubility of the active molecule in the polymers according the invention and the crosslinkability of the matrix polymers according to the invention.

1) A resin is dissolved in a solvent,

2) The active molecule is dissolved in the preparation obtained in 1), 3) Optionally, the solvent is evaporated to bring the collodion to the viscosity state required by the filming technique (film making) chosen;

4) The film is produced by conventional methods such as film coating or spin coating (the filming is done with continued evaporation); 5) The electrical field E is oriented at a temperature at least equal to that of the glass transition (in general Tg greater than or equal to

50 ^β C). Let cool with E until the ambient.

6) Crosslinking under an electron beam e, the duration and intensity of the crosslinking under an electron beam e, being chosen so that the polymer has a glass transition temperature Tg higher by at least 10 ^β C, preferably at least 50 ^β C to the initial one.

The electric field can be cut off after step 5).

A film can thus be obtained whose glass transition temperature

Tg is greater than 300 ^β C. In steps 1 and 2 the role of the active molecule and that of the resin can be reversed.

The technique for the synthesis of host resins is described in particular in the patent applications published under N ^β 2 628 111; 1,555,564 and 2

612 195. For the operation. in the form of film and polarization, techniques are generally used described briefly below.

Film formatting

On a glass plate covered with a conductive layer transparent to the wavelength which will be used, the collodion whose viscosity is adjusted to a value between 1 / 2.10 "2 and 1 / 4.10 ³ , preferably 50 to 200 centipoises by addition or evaporation of solvents and filmed with "Mayer's bar" and this using a film pulling device such as for example that sold under the trade name K control coater of the motorized Erichsen brand.

The film thus obtained is gradually dried up to a temperature at most close to the glass transition temperature (tg); The movie is then dried under vacuum at a temperature close to that of the glass transition for 24 hours.

Once the film is dry, a second conductive layer is deposited and two electrodes are deposited on the conductive layers. The conductive layers are either gold or various conductive oxides, such as tin oxide or mixed oxides of tin and indium.

Polarization

The polarization is preferably carried out at a temperature within 10 ^° C of the glass transition temperature Tg. Tg is measured for example by differential scanning calorimetry (temperature rise to 10 ^β C per minute). The bias voltage is applied between the two layers of gold. This voltage is chosen between 1 and 200 volts per micro / meter (μ m). It is however difficult and rare to obtain this last value because the films tend to snap under a strong potential difference, this is the reason why a voltage between 10 and 100 volts per micro meter is more commonly used, more generally still between 20 and 70 v / μ m. When the polarization no longer varies significantly over time, the operation is then stopped by cooling the film while maintaining a polarization voltage. This bias voltage may be slightly lower than the initial bias voltage. The polymers according to the present invention have shown great inclinations to be polarized and to maintain this polarization over time.

The polymerization techniques such as those which have just been described makes it possible to obtain an average value of cos θ (<cos θ>) is generally between 10 ^-2 and 0.7, more generally between 0.1 and 0 , 5. A voltage of 20 to 25 v / μ m gives approximately a cos θ of 0.1. As it is placed in the zone where the cos θ increases linearly as a function of the field, it is possible by increasing the potential difference between the two faces of the film to increase the orientation of the polymer by increasing the field to a value about 150 volts / μ m area to which there is inflection, the orientation ceasing to grow proportionally with the field. Recall that θ is the angle formed by the orientation of the dipoles with the electric field. This polarization decreases only very slowly over time, unlike the other materials used in non-linear optics. Thus, the compound of example N ^β 2 gives a decrease during the first month of the polarization of less than 5% whereas that of example N ° 3 leads to a compound whose decrease is less than 7%.

This should be compared with the compound consisting of red. 17 (10%) and polymethyl methacrylates (approximately 90%) which was studied in the article by MA Montazani et al. J. opt. plowshare am. (B) vol.6 N ^β 4 page 733 (1989) in which it was indicated that in one month 50% of the polarization had disappeared.

In addition, as these materials exhibit good intersolubility without the need to use chain extenders such as diols, the content of active motif in nonlinear or hyperpolariable optics will be greater and therefore the activity in optics nonlinear of these materials is higher.

These materials are used in particular in optical and optoelectric devices such as, for example, switches, modulators, directional couplers, bistable. The detailed advantages and aims of the invention will appear more clearly in the light of the examples given below only for information.

Example 1

Resin Synthesis

In a 100 ml casting reactor preheated to 165 ° C., a mixture of 21 g of N, N'-4-4'-diphenylmethane bis-maleimide + 9 g of N, N '2.4 tolylene bis is loaded with stirring. -maleimide. Duration of the casting 5 n; 5 g of (N.Vinylpyrrolidone) are melted and added in 0.5 min. Leave to react for 4.5 min. Then added in 0.5 min the mixture of acrylate EBECRYL 150: (7.5 g) Biphenol A polyoxyethyl diacrylate EBECRYL 629: (7.5 g) mixture of 20% trimethylolpropane triacrylate and 80% novolak epoxy acrylate. Homogenize in 2 min; after cooling, a resin is obtained. Examples 2 to 4

Solubilization of active molecules

5 Mixtures are produced according to the following process

10

The active substance is first dissolved in the NVP + solvent mixture.

15 room temperature; the mixture is then added to the warm resin (60 "C) and the mixture is homogenized for 3 min; This gives collodions which can be filmed; the films prepared are of very good quality; percentage of active molecule in the polymer is approximately 5 It is possible to crosslink this film under an electron beam.

20

Active molecules

Fluid lodion collar + homogeneous resin-fluid

35 Example 3:

HO Fluid lodion collar + homogeneous resin-fluid

EXAMPLE 4 Fluid Odor Col + Fluid Homogeneous Resin

CH3-N-CH3

Measurement of the activity of the film of example N ^β 3

The measurement of the coefficients 113 and 333 of electrooptic quadratic susceptibil is carried out by an interferometric method described in the article by R. MEYRUEIX et Col. Fall Meeting of The Mate Research Society - Boston MA (U.S.A.) - Nov. 28 - Dec. 2 1989 - inti "Rotationnal diffusion of Chromophores inside a glassy polymeric studied by electrooptical interfero etry".

Gold electrodes (thickness 200 A (20 n ~) are deposited on the 2 f of the film which is polarized under a field of 25 Volts / μm according to the process described above.

At room temperature, the film is subjected to an alternating voltage of volts-500 Hertz, and traversed under incidence of 45 ^e by a light beam of wavelength 830 nm. The measurement of the film transmittance modulation for the TE and TM polarizations leads to the following values for E / 0 susceptibility at 830 nm:

X 1 3 = 0.3.10-12 _m vl and - ^ 333 = 1.0.10 " ¹² mv ^-1 .

Of course, a more intense polarization field would induce high values for the ~ ^ -.

Claims

1) Composition of the type comprising a matrix formed on the basis of polymer (s) and at least one hyperpolarisable compound characterized in that the main constituent of the matrix is a thermosetting polymer with imide group, preferably with maleimide group.

2) Composition according to claim 1, characterized in that the molecule is attached to the polymer backbone by means of a spacer arm even long.

3) Composition according to claim 1 or 2, characterized in that the active molecule in ONL is not chemically linked to the skeleton.

4) Composition according to claims 1 to 3, characterized in that the concentration of hyperpolarizable compound is between 1 to 20% by mass of copolymer.

5) Composition according to claims 1 to 4, characterized in that said polymer can be obtained by a reaction, at a temperature ranging from 50 ^e C to 180 ^e C, between: - (a) one or more bis-maleimide (s ) corresponding to formula (T)

an N, N'-Bis-imide of formula

in which :

. the symbols Y independently represent H, CH3 or Cl. the symbol A represents a divalent radical chosen from the group consisting of radicals: cyclohexylenes; phenylenes; 4-methyl-1,3-phenylene; 2-methyl-1,3-phenylene; 5-methyl phenylene-1,3; 6-methyl-1,3-phenylene; 2,5-diethyl-3-methyl-1,4-phenylene; and the radicals of formula:

in which T represents a simple valential lien or grouping

and X represents a hydrogen atom, a methyl, ethyl or isopropyl radical; . one (or more) reagent (s) (b) and / or (c);

(b) consisting of one or more substituted heterocyle (s) taken from the group formed by: vinylpyridines, N-vinylpyrrolidone-2, allyl tisocyanurate, vinyltetrahydrofuran; (c) consisting of a compound of the styrene type, such as for example V α -methyl-styrene, divinyl benzene or 1-ethyl-vinyl-benzene.

- and one or more acrylate reagents (d) consisting of one or more compound (s) of general formula: (CH2 = CRÔ - CO - 0 ^~ B in which :

. the symbol R6 represents a hydrogen atom or a methyl radical; . n represents an integer or fractional number at least equal to 1 and at most equal to 8;

. the symbol B represents an organic radical of valence n; derivative: of a saturated, linear or branched aliphatic residue, having from 1 to 30 carbon atoms and which may contain one or more oxygen bridge (s) and / or one or more free hydroxyl function (s) ; an aromatic residue (of aryl or arylaliphatic type) having from 6 to 150 carbon atoms constituted by a benzene ring, which can be substituted by one or three alkyl radicals having from 1 to 5 carbon atoms, or by several benzene rings, optionally substituted as indicated above, linked together by a simple valential bond, an inert group or an alkylene radical having from 1 to 3 carbon atoms, the it remains aromatic, which can contain at various places in its structure one or more bridges ( s) oxygen and / or one or more free hydroxyl function (s), the free valence (s) of the aromatic radical B being able to be carried by a carbon atom of an aliphatic chain and / or by a carbon atom of a benzene ring.

6). Composition according to one of Claims 1 to 5, characterized in that the said hyperpolarizable compound has a non-linear quadratic susceptibility.

7). Composition according to Claim 6, characterized in that the said hyperpolarisable compound is a non-centrosymmetric compound having at least one donor group A, at least one acceptor group linked by a linkage system (s) at least double (s).

8). Material characterized in that it comprises at least part of the polyimide according to claims 1 to 7. 9). Material according to claim 8 characterized in that it is used in the form of a film.

10). Material according to one of claims 1 to 9, characterized in that it is used in the form of a coating.

11). Device containing at least one active element in non-linear optics, characterized in that the said element consists of the material according to one of claims 1 to 10, preferably 9 and 10.

12). Process for the preparation of film according to one of Claims 9 and 10, characterized in that the active molecule in ONL is not chemically linked to the skeleton and that said material is prepared according to a process comprising the following steps:

1) The resin constituting the matrix is dissolved in a solvent;

2) The active molecule is dissolved in the preparation obtained in 1);

3) Optionally the solvent is evaporated;

4) We make the film; 5) Orienting under an electric field E at a temperature at least equal to that of the glass transition waste; allowed to cool with E to ambient; 6) We crosslink under an electron beam e.