DD297028A5 - PROCESS FOR LIGHT-INDUCED ORIENTATION OF LIQUID CRYSTALLINE POLYMERS AND FOR REVERTIBLE OPTICAL INFORMATION STORAGE - Google Patents

Abstract

The process for light-induced orientation of liquid-crystalline polymers and reversible optical information storage is based on the irradiation of photochromic liquid-crystalline polymers with linearly polarized light, whereby an efficient photochemically induced, physical Umorientierungsprozesz photochromic and mesogenic side groups in the viscoelastic or in the glassy state of the polymers. The liquid-crystalline polymer matrix is uniformly macroscopically oriented by light. When used as an optical storage medium, the cycle of the light-induced write process is repeatable with a high change in optical anisotropy, read, thermal, and photonic fade and reorientation processes. By linearly polarized light areas are inscribed with different preferred orientation or repeatedly switched with variation of the polarization plane between different preferred directions {photochromic liquid-crystalline polymers; linearly polarized light; photochemically induced physical reorientation process; Orientation process; reversible optical information storage}

Description

For this 3 pages drawings

Application blot of the invention

The invention relates to a process for light-induced orientation of liquid-crystalline polymers and for reversible optical information storage using photochromic liquid-crystalline side-chain polymers.

Characteristic of the known state of the art

The development of media whose optical properties (absorption, reflection, birefringence, scattering) can be locally reversibly or irreversibly changed by light through physical or photochemical processes is of great interest for optical information storage and display technology.

Irreversible optical memories based on imprinting (CD-ROM) or burning holes in polymers or thin metal layers, producing bubbles in thin metal layers on mostly polymeric substrates or melting wells into thin layers can be obtained by various photochemical variants polymeric and / or organic materials are added. Thus, optical properties can be altered by photopolymerization or photoinduced decomposition, as well as modification of near IR sensitive compounds (G.Kämpf, Ber. Bunsengesell, 89, 179 (1985)).

Photochromic compounds that change color, reflectance, and other optical properties by light, in addition to magneto-optical storage and phase-conversion systems, are also considered for erasable reversible optical data storage (G. Kämpf, Kunststoffe 76, 1077 (1986)).

Such systems are characterized by their much simpler and thus cheaper Herstellu ng by sputtering technician are replaced by spincoats. Other advantages include higher storage densities and a much better signal-to-noise ratio. Erasable optical data storage on the basis of optical or thermal switchable bistable phtochromic compounds speaks the limited durability of photochromic systems at high read / erase write cycle numbers.

In the liquid crystal display technology, laser-addressed displays with low-molecular-weight liquid crystals have been known for some years as a display screen or memory (WE Haas et al., J. Elektrochem., Soc., 121, 1667 (1974), K. Ogura, H. Hirabayashi, A. Uejima K. Nakamura, Jap. J. Appl. Phys., 21, 699 (1982)). However, external fields are required to maintain the memory states and, in addition, the high mobility limits the resolving power and thus the storage density to a considerable extent.

Liquid-crystalline side-chain polymers combine liquid-crystalline properties, in particular their supramolecular order, orientability and the anisotropy of physical properties, with polymer-specific properties, in particular the formation of a glass state. One known way of writing information into thin liquid-crystalline polymer films is to locally heat to the isotropic state by means of an external heat source, preferably a laser beam, to form light-scattering, multi-domain regions as the spot cools. These macroscopically unoriented areas, which have a variation of optical properties, can be frozen in the glassy state of the polymer. This method known as Therme recording is described in DE 3603268 A1 and DE 3603267 A1 (1986). This method is known in numerous variants for liquid-crystalline main and Seitenkettenpclymere without or in combination with external electric or magnetic fields, with macroscopically oriented or unoriented samples and with variation of the Einschreibtemperaturen. The disadvantages of this method are the high laser power required for the writing process and the low resolution.

Such phase transitions can also be achieved by photochemical reactions of photochromic low molecular weight liquid crystals or photochromic liquid crystalline polymers or by the addition of photochromic compounds to liquid crystals or liquid crystalline polymers. Thus, the photoinduced change of the geometric shape of molecules, for example, by EZ photoisomerizations of azo chromophores, can act as a perturbation to the entire liquid crystalline system, thereby photochemically reducing or inducing a phase transition temperature (T.lkeda, Macromol., 23, 36 and 42 [1990]).

Eich and Wendorff (Makromol Chem Commun., 8.59 [1987] and 8, 407 [1987]; OE 362339B AD) describe the erasable optical data storage with photochromic side-chain polymers in the bulk state of the polymers.This laser-induced refractive index change is achieved by a combination of photochemical and thermal effects whereas the photogenerated Z-azobenzene chromophores locally interfere with the polymer's liquid crystalline order and cause a variation of optical property changes, this local perturbation of the mesogenic matrix is maintained even when the azo chromophores relax back to the thermodynamically stable Ε-form This method has the advantage that it takes place with lower writing laser intensities and at room temperature in the range of the glass state of the polymer.

Recently, upon irradiation of azo compounds with linearly polarized light in the glassy state of amorphous polymers, it has been demonstrated that weak dichroism and weak birefringence can be produced by the principle of angle-dependent photoelection (A. Kozak, G. Williams, Mol. Phys. 67, 1065 [1989]).

Birenheide has been able to show on azochromophore-containing liquid-crystalline side-chain polymers (K. Anderle, E. Birenheide, M. Eich, JH Wendorff, Makromol Chem, Rapid Commun., 10, 477 [1989]) that this process takes place in anisotropic polymers owing to the different distribution function of the orientation the azo chromophore is much more efficient in varying optical properties. Birenheide, however, proved for this process and these storage media that only a reorientation of the azochromophores takes place in the glass state as a completely local process which does not disturb the adjacent side chains of the polymer and thus the liquid-crystalline matrix (K. Anderle, R. Birenheide, JH Wendorff, 19th Freiburg Workshop on Liquid Crystals 1990).

The orientation of liquid-crystalline polymers by electric and magnetic fields as well as by mechanical forces and surface effects during shearing or inflow of liquid-crystalline polymers are introduced methods. High laser intensity in liquid crystalline polymers enables mesogenic units locally in the optical field above the glass transition temperature in an anisotropic phase to orient the optically induced Fredericks transition by a nonlinear optical effect (YRShen, Philos. Trans. R. Soc A, 313, 327 [1984]; M. Eich., JM Wendorff, H. Ringsdorf, HW Schmidt, Makromol., Chem., 186, 2639 (1985)).

Endres recently reported the light-induced optical axis reorientation of liquid crystal dye copolymers in the viscoelastic region of planar layers by polarized light (B. Endres, M. Krieg, J. Olme, N. Rau, Polymere and Licht, Bad Nauheim 1990).

Object of the invention

The object of the invention is to develop a process for light-induced orientation of liquid-crystalline polymers and reversible optical information storage by photochromic liquid-crystalline side-chain polymers as storage media, the proposed process overcoming limitations of conventional photochromic systems in polymers and at extremely low light intensities to high levels of photoinduced anisotropy, to high contrast values, to a high amplification factor, to high long-term stability of the stored information, to a high reversibility and to a simple erasability of the information and should allow the light-induced macroscopic orientation of liquid-crystalline side-chain polymers.

Explanation of the essence of the invention

The invention has for its object to develop a method for light-induced orientation of liquid crystalline polymers and for reversible optical information storage, which overcomes limits in the reversibility of conventional photochromic storage media and conventional orientation methods. The object is achieved according to the invention by developing a process for the light-induced, reversible change in the optical anisotropy and orientation of photochromic liquid-crystalline side-chain polymers with linearly polarized or unpolarized light of low intensity. According to the invention the object is achieved in that in a homeotropic, planar or macroscopically disoriented film of a photochromic side groups containing liquid crystalline polymers in the viscoelastic region or below the glass transition temperature of the polymer imagewise or locally with linearly polarized or in the case of a homeotropically oriented film with polarized or unpolarized , Actinic light information is inscribed. The information storage is done using cells consisting of two glass plates between which there is a layer of the oriented side-chain polymer. The insides of the glass surfaces have optionally been provided with organic polymer layers, preferably polyimide, silicon dioxide layers and / or conductive ITO layers, which allow macroscopic orientation of the liquid crystalline polymer layers by electrical or magnetic fields and / or surface forces.

The required film is produced by spin-coating, dipping, casting or by pressing or flowing between two glass plates.

According to the invention, a photo-selection of the photochromic groups which proceeds via an E-Z photoisomerization switches a light-induced reorientation of the entire matrix of the liquid-crystalline polymer during each write-in process. This leads to an orientation of the photochromic and mesogenic side groups perpendicular to the polarization plane of the write-in light. A macroscopically uniform homeotropic layer and also the preferred direction of a planar layer is reoriented by varying the polarization plane of the light in a freely selectable planar preferred direction.

By varying the polarization plane of the actinic light, pixels of different polarization directions can also be written.

The information stored in the storage medium can be read out point by point or area without destroying the stored information by means of a longer-wooled, linearly polarized, non-actinic reading light.

The deletion of the stored information or orientation of the liquid-crystalline matrix takes place according to the invention by light and / or heat lokr 'the surface.

By thermal quenching of the information and subsequent cooling from the isotropic melt, the initial state of the storage medium is restored by itself or by applying an electric or magnetic field.

According to the invention, the above-described write-in, photochemically triggered orientation, reading, thermal or photonic deletion and reorientation process can be repeatedly repeated.

The polymeric storage medium used are liquid-crystalline homopolymers or copolymers of the general formula I, II, III, IV or V in which A is preferably polysiloxane, polyacrylate or polymetharylate and η is 3 to 11 and in IR ¹ = alkyl, 4-alkylcyclohexyl , 4-alkylphenyl, 4-alkoxyphenyl, cychexyl-4-carboxylic acid 4'-alkyl-dodecyl ester, cyclohexyl-4-carboxylic acid 4'-alkyl-cyclohexytester, cholesteryl or cholestanyl and R ² = O-alkyl, in II R ¹ = H, alkyl; O-alkyl or CN, R ² = H, CN or alkyl; and R ³ = H.CN or Al-LylIIIR ¹ = 4-pyridyl or 2-pyrimidyl, in IVR = H, alkyl, O-alkyl or CN and in VR ¹ = H, alkyl, O Alkyl or CN and wherein in the copolymers in addition to the photochromic groups on known mesogenic side groups are included.

Suitable storage media are, for example, poly-Kmethacryloyloxyhexyloxy ^ -methoxyphenylbenzoate-comethacroyloxyhexyloxy-4-methoxystilbene), poly [3 ((4-cholesteryl) oxycarbonylvinylphenoxy) propyl] -meihylsiloxane, poly (3 ((4-propylcyclohexyl) oxycarbonylvinylphenoxy) propylmethylsiloxane or poly [3 ((4-n-hexyloxyphenylcarbonyloxy) cyclohexyl) oxy carbonylvinylphenoxylpropylmethylsiloxane The previously unknown photochromic liquid-crystalline polymers were prepared and characterized by known methods and in analogy to the preparation of described polymers of liquid crystalline polymers Absorption of the photochromic groups emit light, or the absorption of the photochromic side groups of the polymers used is adapted to the wavelength of the irradiation light.The light exposure is carried out for the different photochromic groups I to V, each with suitable wavelengths, in which the photostationary equilibrium between the E and Z photoisomers is set with high quantum yields and a high proportion of Z photoisomers.

Repeated photoselection of the photochromic side groups with a changed polarization plane of the light or with a changed orientation of the planar-oriented storage medium to the polarization plane of the write-in light is repeated between different preferred orientations or memory states and information or orientations are corrected or overwritten. The written information can be erased by light changed PülarisatioMsrichtung without thermal quenching and without the then necessary re-macroscopic orientation. This switching process can be repeated several times and allows a reversible information storage, which is switched only by light. To re-write information, a deletion is not required.

Irradiation with unpolarized light also removes the preferred direction and changes the memory state.

Pixels having different orientations are written in and read out when the writing and reading processes are performed with linearly polarized light of different polarization direction in the orientation dos jr preferred direction of the storage medium.

By means of light-induced orientation, layers with domains of various preferred directions or macroscopically uniformly homeotropically oriented layers of photochromic liquid-crystalline polymers are produced in layers oriented in a planar manner.

Using linearly polarized light, planar oriented layers with a preferred direction are obtained.

According to the invention and in a surprising manner, the method and storage media used are by no means merely a local reorientation of the photochromic groups or molecules, but the photoinduced rotational diffusion or angle-dependent photoselection of the photochromic groups in storage media switches the entire anisotropic liquid-crystalline matrix both in the viscoelastic region and, most surprisingly, in the glassy state of the polymers.

The orientation of the photochromic groups and mesogenic side groups is continuously changed by the photoselection and takes place until the orientation of the matrix perpendicular to the polarization plane of the light. The information is written point-like surface with a laser or using a lithographic mask, or a lamp with an intensity of 0.1 to 10mWcm ~ ² in a time between 1 and 600sec. After multiple photonic switching processes, an intermediate thermal heating process in the viscoelastic region of the polymers overcomes the limitations of conventional photochromic storage media through physical aging.

The information storage method claimed according to the invention leads, by the system-specific combination of photochromic groups with mesogenic side chains, to a surprisingly extremely efficient photochemically induced physical reorientation process when irradiated with linearly polarized light, which macroscopically unites the orientation of photochromic and mesogenic side groups and the efficient change of the anisotropic optical Properties like dichrcism and birefringence switch. Particular advantages of the process for storing information and orientation of liquid-crystalline polymers include:

high amplification factor and thus extremely efficient writing process by photochemically induced reorientation of the photochromic groups and thereby physical orientation of the entirety of the mesogenic side groups of the liquid-crystalline storage medium,

hoho efficiency allows the use of low intensity light sources, short irradiation sites and low photochromic group polymers,

high optical contrast due to the reorientation of the photochromic groups and the non-photoreactive mesogenic side groups,

Process-related decoupling between process-inducing photoproduct of the photochromic group and the memory state based on altered orientation of photochromic and mesogenic side groups, so that the thermal stability of the photoproducts is irrelevant,

simple thermal erasability of information and orientations,

- simple photonic erasability of information and orientations,

low light exposure leads to high reversibility and high cycle numbers of the optical information storage method,

Switching with light of different polarization direction between different memory states, so that information can be corrected or deleted in a spatially selective or light-free manner without the need for conventional thermal quenching and reorientation processes, thus representing a completely new type of optical information storage method.

- By pixels of different polarization direction of the information content of each pixel and thus the total information and memory density is increased by pixels of different polarization directions, so that a three-dimensional information storage is realized,

- Fatigue of the storage medium due to repeated photonic switching processes are resolved by intermediate thermal heating and reorientation of the medium, thus e'ne essential limit of conventional photochromic polymers overcome,

the reorientation of some storage media by heating in the isotropic melt and subsequent Abi ühlen takes place to the original, macroscopically uniform homeotropically oriented layer without external fields,

the resolution is 0.5 μm when using UV light and described storage media,

the information is long-term stable at room temperature and is retained even in the case of thermal re-reaction of the photochromic groups,

macroscopically uniform orientation of liquid crystalline polymers by light without the use of magnetic or electric fields or surface forces,

- in contrast to all other known "experience the storage of information with photochromic liquid crystalline polymers and the orientation of liquid crystalline polymers is carried out by this ancestor below the glass transition temperature a cooperative reorientation of photochromic and mesogenic side groups to macroscopically uniformly oriented areas of liquid crystalline polymer layers,

the preferred direction of planar oriented layers can be changed in the plane solely by variation of the polarization plane and continuously by light intensity and irradiation time,

- By the absorption of photochromic groups only in the UV range, an increase in storage capacity is achieved in comparison to all known azochromophore storage media,

the short-wave absorption of the photochromic groups simplifies the protection of the written information,

the significant change in birefringence predestines an application of the method in reversible analog data storage, in reversible digital data storage or in reversible synthetic holography,

- allows the procedure. Films of photochromic liquid-crystalline polymers in various applications, for example, as an orientation layer, macroscopically uniformly orient by light.

The proposed method for reversible optical information storage and light-induced orientation of liquid crystalline polymers based on a linearly polarized light photochemically induced, physical Umorientierungsverfahrens with previously unknown photochromic liquid crystalline polymers in the viscoelastic region and below the glass transition temperature was not derivable from previously known publications and patents and has in the Efficiency, in contrast, in the fieversibilität, in the storage density and light-induced process steps particularly good properties over all previously known methods and systems.

embodiment

The memory cell consists of two glass plates coated with a polyimide layer and an intermediate layer of the liquid-crystalline polymer poly [3 ((4-propylcyclohexyl) oxycarbonylvinylphenoxy) propylmethylsiloxane as storage medium. By heating the polymer in the isotropic melt, pressing in the viscoelastic region 5 ° C below the phase transition nematic-isotropic at 93 ⁰ C and then annealing at this temperature for two hours, the polymer was oriented. The cell was slowly cooled to room temperature. The smectic polymer has large homeotropically oriented domains in the cell.

The storage medium in the cell was imagewise irradiated with unpolarized or linearly polarized, using polarizing films, 313 nm light of HBO 500 in combination with a metal interference filter at a radiation power of 0.5 mW / cm ² 140s.

With the aid of a UV spectrometer, as a consequence of the light exposure, a drastic increase in the extinction in the absorption range of the cinnamoyl groups is measured. The experiment proves the light-induced change in optical anisotropy by changing the dichroic ratio of the photochromic groups. The typical degradation spectrum for the photolysis of the polymer in solution, using cyclohexane as solvent, is shown in Fig. 1 a. The photolysis of the cinnamoyl group in solution and in amorphous polymers always results in a decrease in the extinction. In the homeotropic film of the same polymer, a comparable increase in absorbance is observed under comparable irradiation conditions (Figure 1 b) !. The irradiation times are given in seconds. With a polarizing microscope, a change in birefringence between irradiated and unirradiated films is detected. This demonstrates the change in a homeotropic orientation into a planar orientation of the entire liquid-crystalline matrix. The information written in is read out by the increase in extinction in the region of cinnamoyl sorption by UV light or by longer-wave, linearly polarized non-actinic light, wavelength preferably greater than 350 nm. The inscribed information is stable in the glassy state and in the viscoelastic region. The written information or orientation is erased by heat. Upon cooling, the liquid-crystalline storage medium orients itself back from the isotropic melt, or with additional application of a magnetic field, to the original homeotropic orientation. The writing, reading, deleting and orientation process can be repeated many times.

exemplary

Using the memory cell and irradiation conditions described in Embodiment 1, regions of different preferred orientation of the planar layers at comparable irradiation times are written with polarized light of wavelength greater than 300 nm and varied by polarization microscopy.

embodiment

By using the memory cell and irradiation conditions described in Patent Application Example 1, a preferred orientation is written in with polarized light of wavelength greater than 300 μm and read out by polarization microscopy. If, however, the polarization plane of the light and the storage medium are irradiated again with polarized light but with a changed orientation, preferably in the preferred direction of the photochromic groups, then the preferred direction changes continuously with the irradiation time until orientation is maximally perpendicular to the polarization plane of the actinic light. The new preferred direction was identified by polarization microscopy and UV spectroscopic.

Ausführungsbeisplel

A film of the smectic liquid-crystalline polymer poly [3 ((4-n-hexyloxyphenylcarbonyloxy) cyclohexyl) oxycarbonylvinylph enoxy) propyl] methylsiloxane is applied to a quartz plate by spin coating from a chloroform solution. The layer is annealed two hours at 100 ⁰ C viskoelstischen area. The homeotropic layer is imagewise irradiated with unpolarized light of the wavelength 313 nm of an HBO 500 in conjunction with a metal interference filter at a radiation intensity of 0.5 mW / cm ² 140 s. The EZ photoisomerization causes a Zunal ne the extinction in the cinnamoyl absorption and the polarization microscopically detectable conversion of the homeotropic orientation in a planar orientation. With heat supply the orientation is lost. The process takes place in the viscoelastic region and below the glass transition temperature of the polymer.

Ausführungsbelsplel

Between two quartz plates, a film of the liquid crystalline polymer poly is produced (methacryloyloxyhexyloxy-4-methoxyphenyl benzoate-co-methacryloyloxyhexyloxy-4-mothoxy-stilbene) in the isotropic melt and nematic in the magnetic field 5 ⁰ C below the phase transition / isctrop homeotropically oriented. The ratio between phenyl benzoate groups and photochromic stilbene side groups is 10: 1. The cell is imagewise irradiated with unpolarized light of wavelength 300nm below the glass transition temperature of the polymer. With a UV-vis spectrophotometer, an increase in absorbance in the region of the absorption of the stilbene groups is observed as a result of the light exposure. Since the R-2 photoisomerization of the polymer in solution always leads to a decrease in the extinction, the increase in extinction in the anisotropic film of the liquid-crystalline polymer is due to a light-induced change in the optical anisotropy due to altered orientation of the μήοί .xnromen groups. Polarization microscopy observes a change in the birefringence of the liquid-crystalline matrix due to a change in orientation between irradiated and unirradiated areas. The written information is erased by heat.

Claims (11)

1. Ve go for light-induced orientation of liquid crystalline polymers and for reversible optical information storage using photochromic liquid crystalline polymers as a storage medium, characterized in that in a homeotropic, planar or macroscopic disoriented, by spin-coats, dipping, casting or by pressing or inflow between two glass plates a film of a photochromic side group-containing liquid-crystalline polymer in the viscoelastic region or below the glass transition temperature of the polymer imagewise or locally with linearly polarized or in the case of a homeotropically oriented film with polarized or unpolarized, actinic light information is written or pixels of different Pclarisationseinrichtungen be inscribed and that at each enrollment process, a photo-selection of the photochromic groups proceeding via photoisomerization leads to a light-induced reorientation For the entire liquid crystal matrix up to an orientation of the photochromic and mesogenic side groups perpendicular to the polarization plane of Einschreiblichtes switched macroscopically and uniformly a homeotropic layer to a planar layer and / or the preferred direction of a planar layer by varying the plane of polarization of the light is reoriented in any desired planar preferred directions and that the information stored in the storage medium information is read out by point-wise or flat without longer destroying the stored information by longer-wavelength, non-actinic, linearly polarized reading light and that the stored information or orientation of the liquid-crystalline matrix is locally erased by light and / or heat and by thermal quenching of the information and subsequent cooling, restoring the initial state of the storage medium by itself or by applying an electric or magnetic field, and that the write, photochemically triggered orientation, reading, thermal or photonic quenching and reorienting process is multiply repeatable , 2. The method according to claim 1, characterized in that are used as the polymeric storage medium photochromic liquid crystalline homo- or copolymers of the general formula I, II, III, IV or V, in which A is preferably for polysiloxane, polyacrylate or polymethacrylate and η for 3 to 11 and IR ¹ = alkyl, 4-alkylcyclohexyl, 4-alkylphenyl, 4-alkoxyphenyl, cyclohexylcarboxylic ^ '- alkylphenyl ester, cyclohexyl-4-carboxylic acid 4'-alkylcyclohexyl ester, cholesterol or cholestanyl, and R ² = O-alkyl, in R ¹ = H, alkyl, O-alkyl or CN, R ² = H, CN or alkyl and R ³ = H, CN or alkyl, in III R ¹ = 4-pyridyl or 2-pyrimidyl , in IV R = H, alkyl, O-alkyl or CN and in VR ¹ = H, alkyl, O-alkyl or CN, and wherein in the copolymers in addition to the photochromic groups per se known mesogenic side groups are included. 3. The method according to claims 1 and 2, characterized in that as storage medium, for example, poly-flmethacryloyloxyhexyloxy ^ -methoxy-phenylbenzoat-comethacryloyloxyhexyloxy-4-methoxystilben)], poly [3 ((4-cholesteryljoxycarbonylvinylphenoxyjproylj-methylsiloxane, poly [3 ((4 -propylcyclohexyl) oxycarbonylvinylphenoxy) propyl] methylsiloxane or poly [3 ((4-n-hexyloxyphenylcarbonyloxy) cyclohexyl) oxycarbonylvinylphenoxy) propyl] methylsiloxane. 4. The method according to claims 1,2 and 3, characterized in that the absorption of the photochromic side groups of the polymers used is adapted to the wavelengths of the irradiation light and that the photostationary equilibrium between the E and Z photoisomers with high quantum yields and high proportion is adjusted at Z-photoisomers by light exposure, each with suitable wavelengths. 5. The method according to claim 1, characterized in that light sources are used for the writing process, which emit in the region of the absorption of the photochromic group mono- or polychromatic, linearly polarized or unpolarized light. 6. The method according to claim 1, characterized in that is repeatedly switched by a repeated photoselection of the photochromic side groups with a changed polarization plane of the light or with changed orientation of the planar oriented storage medium to the polarization plane of Einschreiblichtes between different preferred directions or memory states and corrects or overrides information or orientations become. 7. The method according to Anspriuh 1, characterized in that the write-in and the reading process with linearly polarized light of different polarization directions in alignment with the preferred direction of the storage medium takes place and pixels of different orientation are written and read. 8. The method according to claim 1, characterized in that from layers with domains of different preferred direction or macroscopically uniformly homeotropically oriented layers of photochromic liquid-crystalline polymers surface oriented layers and using linearly polarized light area oriented layers are produced with a preferred direction by light-induced orientation. 9. The method according to claims 1, 7 and 8, characterized in that the orientation of the photochromic groups and the totality of the liquid-crystalline matrix is continuously changed by the photoselection and until the setting of the preferred direction of the matrix is perpendicular to the polarization plane of the light. 10. The method according to claims 1,7 and 8, characterized in that the information with a laser punctiform or using a lithographic mask is written flat or with a lamp. 11. The method according to claims 1 and 6, characterized in that takes place after repeated photonic switching processes an interposed thermal heating in the viscoelastic region of the polymer.