KR101612725B1 - Maleimide-n-vinyllactam based sidechain polymers for lcd alignment layers - Google Patents

Abstract

Wherein the polymer is a copolymer comprising repeat units of maleimide and / or a derivative thereof and N-vinyl lactam and / or a derivative thereof, and at least a part of the repeat unit is a Pendant side chains. The polymer of the present invention is suitable for use as an orientation film material in a liquid crystal device or as an orientation film material.

Description

MALEIMIDE-N-VINYLLACTAM BASED SIDECAIN POLYMERS FOR LCD ALIGNMENT LAYERS [0002]

The present invention relates to a liquid crystal device comprising a polymer for a surface-director alignment layer, a surface-director oriented film material comprising such a polymer, and an alignment layer comprising such a polymer.

A liquid crystal device generally includes a layer of a liquid crystal material arranged on a substrate or interposed between a pair of substrates.

Liquid crystal molecules are typically relatively hard molecules with a pronounced shape anisotropy and are molecules that can be oriented along their long axis in certain desirable directions. The average direction of the molecules is defined by the amount of the vector, which is called a director.

In the liquid crystal display, the initial alignment of the liquid crystal layer to be obtained in the absence of an external field such as an electric field is generally performed by a method such as applying an alignment layer (alignment layer) on a limited substrate surface facing the liquid crystal bulk , By properly treating the surface of the limited solid substrate. The initial liquid crystal alignment is defined as the solid surface / liquid crystal interaction at the interface between the liquid crystal layer and the alignment layer.

Since the alignment of the liquid crystal molecules adjacent to the limited surface is transmitted to the liquid crystal molecules in the bulk through the elastic force, essentially the same orientation is given to all the liquid crystal bulk molecules.

The director of the liquid crystal molecules near the interface between the liquid crystal layer and the alignment layer (here also referred to as the surface director) is aligned with a defined substrate surface, also referred to as a homogeneous or planar orientation (PA), with homeotropic Referred to also as a tilted alignment (TA) relative to a defined substrate surface, or defined as a point in a particular direction, such as vertical to a defined substrate surface, also referred to as a vertical alignment (VA) And is limited to a tilt angle. The type of orientation used in the liquid crystal display depends on the application of the device to be obtained.

Known methods for establishing an alignment layer are, for example, an inorganic film vapor deposition method and an organic film rubbing method. In the inorganic film vapor deposition method, an inorganic material such as silicon oxide is deposited obliquely on a limited surface so that the liquid crystal molecules are oriented in a specific direction by the inorganic material and the evaporation conditions by the inorganic film, thereby forming an inorganic film on the substrate surface. This method is not suitable for large-scale production because the manufacturing cost is high, and this method is not actually used.

According to the organic film rubbing method, for example, an organic coating of polyimide is formed on the substrate surface. The organic coating is then rubbed in a set direction using a cloth such as cotton, nylon or polyester, and the liquid crystal molecules in contact with the layer are oriented in the rubbing direction.

Polyimides are used in most cases as organic surface coatings because of their relatively favorable properties such as chemical stability, thermal stability and the like. Application of the polyimide layer generally involves a baking step at 200 to 300 占 폚 as described below.

Polyimides can be prepared according to, for example, Scheme I or Scheme II below:

In the first step, an equimolar amount of tetracarboxylic acid anhydride and diamine are mixed in an amide solvent such as N-methylpyrrolidone (NMP). A spontaneous reaction takes place, and polyamic acid, which is a prepolymer of polyimide, is formed. In this state, the prepolymer is supplied to a user such as a LCD manufacturer. However, since the prepolymer solution is unstable at room temperature, the solution is generally cooled during transportation and storage to avoid decomposition of the prepolymer or any other undesirable chemical reaction.

In general, polyamic acids are often diluted by the liquid crystal device manufacturer to about 5% with a 4: 1 (w / w) mixture of NMP and butyl cellosolve.

The polyamic acid is generally applied on a glass substrate coated with a transparent and patterned indium tin oxide (ITO) electrode layer using, for example, spin coating or a type of printing technique. The layer of polyamic acid is then dried in an oven at about 100 캜 and then heated to about 200 캜 for one to two hours. In this heating cycle, the polyamic acid is converted to polyimide. This step is also referred to as hardening or baking of the polyimide. The resulting polyimide is thermally very stable and insoluble in all solvents.

The polymer can be removed only by, for example, decomposing using an alkaline medium.

A disadvantage of this organic film application process is a baking step which results in a long production time and a high production cost.

Also, a high temperature, such as about 200 캜, is undesirable because it can reduce the yield in the manufacture of liquid crystal-on-silicon (LCOS) and thin film transistor (TFT) and thus result in film defects. The required baking temperature is also too high for use on plastic substrates.

Also, it is difficult to control the anchoring strength between the organic film and the liquid crystal bulk layer, which is applied using the organic film application process.

In addition, one of the disadvantages of the polyimide approach is that the polyamic acid is very unstable and must be stored at such low temperatures as in a freezer.

It would be highly advantageous to avoid some or all of these shortcomings.

It is an object of the present invention to overcome the problems of the prior art at least in part and to provide a material which can be advantageously used as an alignment film material or as an orientation film material, such as for a liquid crystal device.

The inventors of the present invention have found that this object can be achieved at least in part by providing a polymer based on maleimide and N-vinyl lactam repeating units in accordance with the claimed invention.

Thus, in a first aspect, the present invention is a polymer for use in a surface-director alignment film, wherein the polymer is a copolymer comprising repeat units of maleimide and / or a derivative thereof and N-vinyl lactam and / , At least a portion of said repeat units being functionalized by a pendant side-group S ^x .

The polymer of the present invention has high light stability and thermal stability. The copolymer of ethylmaleimide and vinylpyrrolidone has been shown to promote a stable and high quality alignment layer at temperature and its properties are comparable to those of commercial polyimides. The copolymer is very stable, so long as the side chain is appropriately selected so as not to reduce its stability due to its instability.

The solubility of a wide variety of copolymers with different side chains is very good in standard solvents such as NMP and PGMEA.

Compared to conventional polyimides, the polymers of the present invention are much more stable in solution and do not require cryogenic storage. Further, the polymer of the present invention is easier and quicker to process than polyimide because it does not require curing at high temperature and does not require curing and forms a polymer film on a glass or plastic substrate.

The side-groups S ^X may be attached to the repeating unit through a spacer group L.

The amount of maleimide and N-vinyl lactam repeating units may be at least 50%, such as at least 75%, such as at least 90%, of the repeat units of the polymer backbone. Also, the ratio of maleimide to N-vinyl lactam in the polymer backbone can be from 1:10 to 10: 1, such as from 1: 2 to 2: 1, such as about 1: 1.

The N-vinyl lactam of the polymer of the present invention may be selected from the group consisting of N-vinyl pyrrolidone, N-vinyl piperidone and N-vinyl caprolactam. The polymer may also comprise a repeating unit functionalized by an anchoring side-group S ⁴ ; A repeating unit functionalized by a pendant side-group S ⁵ selected from aliphatic and aromatic groups, such as alkyl, aryl or alkylaryl, polyether, siloxane or alcohol, which are optionally substituted, halogenated, branched or straight-chain; A repetitive unit functionalized by an ionic motion inhibiting side-group S ⁶ ; Reactive, preferably repeating units functionalized by the light-reactive side-group S ⁷ ; And a repeating unit selected from repeating units functionalized by the light-responsive side-group S ⁸ . The polymer optionally comprises a crosslinking group.

In embodiments of the present invention, the polymer has pendant side with prominent shape anisotropy - comprises repeating units functionalized by the groups S ^1. The side-group S ¹ having the remarkable shape anisotropy can be selected from a side-group S ^1a inducing a planar alignment of the liquid crystal material and a side-group S ^1b inducing a vertical orientation of the liquid crystal material.

At least a portion of the side-groups may be attached to the repeat unit via maleimide-nitrogen.

In another aspect, the invention is directed to a surface-director alignment film comprising one or more polymers according to the present invention deposited on a solid substrate.

In another aspect, the present invention provides a liquid crystal device comprising at least one defined substrate, a liquid crystal bulk, and a surface-director alignment film disposed between the at least one defined substrate and the liquid crystal bulk and in contact with the surface of the liquid crystal bulk, Surface-director alignment film comprises a polymer according to the present invention. For example, the liquid crystal device may include first and second substrates including the liquid crystal bulk layer therebetween; A first surface-director alignment film is arranged between the first substrate and the liquid crystal bulk and is in contact with the surface of the liquid crystal bulk; A second surface-director alignment film is arranged between the first substrate and the liquid crystal bulk and is in contact with the surface of the liquid crystal bulk; One or more, preferably all, of the first and second surface-director alignment layers comprise a polymer according to the invention.

In another aspect, the present invention provides a method of manufacturing an alignment film comprising: providing an alignment film material according to the present invention; And irradiating the alignment film material with linearly polarized electromagnetic radiation having a wavelength in the range of 200-300 nm. ≪ RTI ID = 0.0 > [0002] < / RTI > In particular, the linearly polarized electromagnetic wave may have a wavelength in the range of 230 to 270 nm, for example about 250 nm.

According to the present invention, there is provided an improved material of the prior art which can be used for an alignment film material or for an alignment film material for a liquid crystal device.

1 is a block diagram illustrating a photo-orientation method of an alignment film material of the present invention.
2 is an exemplary view of a liquid crystal device using the alignment layer of the present invention.

The present invention relates to a polymer suitable for use in an alignment film material for a liquid crystal device or as an alignment film material.

The polymer of the present invention is a copolymer comprising repeating units of maleimide, N-vinyl lactam such as vinyl pyrrolidone, N-vinyl piperidone and N-vinyl caprolactam, and derivatives thereof, At least some of which are functionalized by a pendant side-group.

As used herein, the expression "a copolymer comprising repeating units of maleimide and N-vinyl lactam" and equivalents thereof means that a copolymer obtainable by polymerization from a mixture of maleimide monomer and N-vinyllactam monomer it means.

The N-vinyl lactam is a compound of formula (I)

In the formula, _x in (CH ₂ ) _x means an integer of 2 to 10, typically an integer of 3 to 5.

As used herein, maleimide is a compound of formula II:

Formula, S ^x is a side described in H, methyl, ethyl or the specification - is selected from the group ^{S 1, S 4, S 5} , S 6, S 7 , and the group of S ^8, L is a side-maleimide a group S ^x Lt; RTI ID = 0.0 > nitrogen < / RTI > In the absence of the spacer L, the side-groups S ^x are attached directly to the nitrogen of the maleimide ring.

The mixture of N-vinyl lactam and maleimide can be polymerized by methods well known in the art, and typically maleic anhydride and N-vinyl lactam are formed by radical addition copolymerization.

For such mixtures of N-vinyllactams and maleimides, blends of different maleimides, i.e. blends of two or more different maleimides with different side-groups S ^x and / or spacers L, can be used. This results in the formation of copolymers with one or more side-groups and / or linkers attached to the polymer backbone.

Such different maleimide blends can be utilized to control the properties of the resulting polymer. Non-limiting examples of such maleimide blends are further described herein below.

Examples of suitable polymerization reactions are illustrated in the following examples.

The result of the polymerization is a copolymer according to the present invention comprising maleimide and repeating units of N-vinyl lactam having the general formula:

In the resulting copolymer, the maleimide and N-vinyl lactam units are not regularly distributed, and therefore the polymer can not produce an accurate structural formula because the polymer is not a perfect hyperbranched copolymer as its form implies.

However, at a 1: 1 molar ratio of maleimide and N-vinyl lactam monomer in the reaction mixture, the arrangement in the resulting polymer is inherently prone to an overbased maleimide-N-amino lactam-maleimide-N-amino lactam structure.

As will be apparent to those skilled in the art, the polymers of the present invention may include additional repeat units other than maleimide and N-vinyl lactam repeat units. Examples of such repeating units include monomers or prepolymers that can be incorporated into the polymer chain by radical addition polymerization, typically any polymerizable ethylenically unsaturated compound known to those skilled in the art. Examples of such polymerizable ethylenically unsaturated compounds include, but are not limited to, styrene and (meth) acrylate.

In embodiments of the present invention, the total amount of maleimide and N-vinyl lactam repeat units occupies a significant portion of the repeat units in the polymer. Typically, the recurring units constitute at least about 50%, such as at least about 755, such as at least about 905, based on the number of recurring units of the polymer chain. 100% maleimide and N-vinyl lactam may also be envisaged.

In the polymer of the present invention, the number ratio between the maleimide repeating unit and the N-vinyl lactam repeating unit is, for example, in the range of 1:10 to 10: 1, preferably 1: 2 to 2: 1, Can be about 1: 1.

The closer the ratio is to 1: 1, the more stable the polymer composition during polymerization, and the less the necessity of adjusting the feed of the composition during polymerization to maintain the same polymer composition, since such copolymerization is close to overbite.

A high ratio (excess of maleimide) will result in short polymer. Low ratio (excess of N- vinyl lactams), the polymer is normally a side-group because it is a maleimide having the S ^x, the side-group (S ^x) content will result in less polymer.

The copolymers of the present invention are soluble in standard solvents such as NMP and PGMEA and therefore solutions of the polymers can be prepared by conventional lamination methods such as, but not limited to, spin-coating, spray-coating, Coating, flex printing, ink-jet printing, dipping, and the like.

Since the polymer can be prepared and dissolved in a polymerized state, the alignment layer can be easily obtained by simply evaporating the solvent after lamination on the substrate. This allows the use of temperature sensitive substrates since excessive heating is not required to obtain an alignment layer.

In addition, since the polymer does not require curing after lamination, the total time taken to form the alignment layer on the substrate is very short, since it only involves evaporation of the very thin solvent film following the lamination.

The pendant side-groups S ^x attached to maleimide monomers, typically through maleimide ring nitrogen, can include, for example, side-groups selected from the following: optionally substituted, straight-chain or branched Reactive side groups, reactive side groups, reactive side groups, reactive side groups, reactive side groups, photo-reactive side groups, photo-reactive side groups, And side-groups having noticeable shape anisotropy. However, other side-groups for use in the present invention may be contemplated.

The side-groups S ^x , when necessary, can be attached to the polymer backbone by a spacer group L, each of which typically comprises from 0 to 30 connecting atoms, for example from 0 to 5 and 15 connecting atoms, Where 0 connecting atoms indicate that the side-groups are attached directly to the polymer backbone through direct bonding. However, it is contemplated that spacer groups longer than thirty connecting atoms may be used in the present invention.

The spacer group L may be utilized, for example, to promote adhesion of the side-groups S ^x to the maleimide ring nitrogen, and may be utilized to increase the mobility of the attached side-groups.

The spacer group L is typically an optionally substituted saturated or unsaturated hydrocarbon chain such as alkyl, alkenyl, aryl, alkylaryl, alkoxy or polyether, aryloxy group, siloxane chain. Typical examples include C ₅ -C ₁₅ alkyl or alkyloxy chains.

In embodiments of the present invention, side-groups S ¹ with noticeable shape anisotropy may be attached to the polymers of the present invention.

For example, molecules (mesogens) of liquid crystal materials are typically molecules that exhibit such remarkable shape anisotropy.

As used herein, the term " side-group with noticeable shape anisotropy "means a molecule having noticeable shape anisotropy in a real environment. The side-group with noticeable shape anisotropy exhibits a distinct difference between its short axis and long axis, and is structurally relatively rigid.

In an embodiment of the present invention, the side-groups with noticeable shape anisotropy are mesogenic side-groups.

Handbook of Liquid Crystals, vol 1 Fundamentals, pub. As defined by John Wiley & Sons Inc, 1988, the term "mesogenic" relates to structures that are generally compatible with mesophase formation. This definition is used throughout this specification.

Thus, the mesogenic side-group is a side-group with a mesogenic structure.

In the "Handbook of Liquid Crystals (Above) ", mesogens are the same as compounds which may exist as mesomorphic compounds, i.e., intermediates, i.e. liquid crystals, under suitable conditions of temperature, pressure and concentration.

Mesogens are a typical example of molecules with remarkable shape anisotropy. Thus, side-groups containing mesogens are included in this definition. On the other hand, the side-groups do not have to be mesogens to be the mesogenic side groups, and it is also believed that non-mesogenic mesogenic side-groups can be used in the present invention.

The side-group S ¹ according to the present invention, which has a pronounced shape anisotropy, is of the calamitic, discotic, sanidic, pyramidal, curved (such as banana Quot;), a chevron, or other shapes that exhibit noticeable shape anisotropy.

The surface properties of the substrate affect the orientation of the mesogens of the liquid crystal layer in contact with the substrate surface at least at the interface between the substrate surface and the liquid crystal layer.

Typically, since the interfacial conditions propagate through the liquid crystal layer, the entire liquid crystal layer orientation is affected by the orientation at the interface.

Two main paths are used to influence the orientation of the liquid crystal layer. One path (surface energy path) increases the compatibility with the tail of the liquid crystal material promoting vertical orientation (low surface energy) as in Example 10 below, Is a method that utilizes general surface properties to increase compatibility with a mesogenic core that promotes alignment (high surface energy). The other path is a method of using a three-dimensional interaction to align the liquid crystal. Such a stereoscopic interaction is particularly prominent when the liquid crystal layer is in contact with the substrate surface which exhibits a group having a predominantly shape anisotropy such as linear, rod-like and disc-shaped, resulting in mesogens at the interface between the liquid crystal layer and the substrate surface And tend to align with the orientation of the groups with defined shape anisotropy appearing on the substrate surface.

For example, the substrate surface representing the group may have a shape anisotropy such as linear, rod-shaped, and disc-shaped, aligned in essentially planar alignment with respect to the substrate surface, and mesogens at the interface toward the substrate surface may also be aligned They tend to be aligned in a planar state.

On the other hand, utilizing a substrate surface that exhibits a group in which the shape anisotropy is essentially vertically aligned with respect to the substrate surface, the mesogens at the interface toward the substrate surface also tend to align vertically with respect to the substrate surface.

Alternatively, the side-groups having noticeable shape anisotropy are aligned to the orientation of the mesogens of the liquid crystal layer at the interface.

By utilizing side-groups with shape anisotropy defined in the polymers of the present invention, liquid crystal materials such as LC-layers of liquid crystal devices tend to align with the orientation of the side-groups attached to the polymer backbone.

Therefore, the polymer of the present invention having a side-group having remarkable shape anisotropy affects the orientation of the mesogen at least at the interface between such an alignment film and the liquid crystal layer in contact with the alignment film, and therefore, Can be advantageously used for an alignment film.

In one embodiment, side-groups S ^1a , which have noticeable shape anisotropies such as linear, rod-like, and disk-like, leading to planar alignment of the mesogens at the interface, i.e. essentially parallel to the substrate surface, Of the polymer. An alignment layer based on such a polymer can be used to enhance the planar alignment of the liquid crystal layer. An exemplary, non-limiting example of such a polymer is described in Example 6 below.

In another embodiment, the side-groups S ^1b , which have noticeable shape anisotropies such as linear, rod-shaped and disk-like, induce a vertical orientation of the mesogens at the interface, i.e. essentially perpendicular to the substrate surface Can be attached to the polymer of the present invention. An alignment layer based on such a polymer can be used to enhance the vertical orientation of the liquid crystal molecules. Exemplary, non-limiting examples of such polymers are described in Examples 1-3 below.

For example, in a linear side-group with noticeable shape anisotropy, the side-on attachment of the side-groups can have a long axis along the polymer surface to promote horizontal (planar) alignment. On the other hand, the end-on attachment of linear side-groups can enhance vertical alignment (homeotropic alignment) with the major axis at right angles to the polymer surface. However, in the case of a side-group having a curved shape (so-called banana shape), the side-on adhesion to the polymer backbone can promote the tilted alignment of the liquid crystal molecules and the end- .

Known as "linear" side-airway calamitic, rod-shaped and rod-shaped side-groups with pronounced shape anisotropy. The linear side-groups have a clearly defined major axis extending along the main extension of the molecule and a minor axis perpendicular to the major axis.

As used herein, the term " end-on attachment " refers to a linear side-group with a pronounced shape anisotropy attached to the polymer backbone by a spacer attached to the side-group at the end or end of the long axis of the side- And the spacer is essentially parallel to the long axis of the side-group. For example, in a rod-like side-group, such as a calamitic mesogenic group, the point of attachment is at or near one of the distal ends of the side-groups.

The term " side-on attachment ", as used herein, refers to a linear side having a predominantly shape anisotropy affixed to the polymer backbone by a spacer attached to the side-group such that the spacer is essentially perpendicular to the long axis of the side- - means the group.

For further definitions of terms related to liquid crystals and related terms, "Definition of Basic Terms for Low Molecular Weight and Polymer Liquid Crystals" (IUPAC Recommendations 2001, Pure Appl Chem, Vol 73, No 5, pp 845-895, 2001) , The contents of which are incorporated herein by reference in their entirety.

In an embodiment of the present invention, the anchoring sidewall S ⁴ may be preferably used to secure the polymer to the underlying substrate. The anchoring side groups S ⁴ are typically optionally substituted C ₂ to C ₂₀ , for example C ₂ to C ₈ , hydrocarbon chains with functional groups at the ends spaced from the polymer backbone, Can form bonds such as covalent bonds, ionic bonds or hydrogen bonds to chemical groups on the surface, examples of which include, but are not limited to, free hydroxyl groups on the glass surface, such as epoxy introduced by preactivating the substrate surface, Amino, thiol or isocyanato group.

Non-limiting examples of such functional groups suitable for anchoring side-groups include amino, hydroxy, isocyanato, and glycidyl groups. Those skilled in the art will be able to select suitable functional groups on the anchoring side-groups depending on the substrate material.

Non-limiting examples of anchoring side-groups S ⁴ are shown in Structural Formulas (III) to (VI) below, wherein Z represents a portion of the polymer backbone as before, and L is preferably an alkylene, Is a spacer group having a length of 10 spacer atoms, for example 1 to 5 spacer atoms:

The physicochemical properties of the polymers of the present invention, such as glass transition temperature T _g , modulus of elasticity, cohesiveness of the laminated film, film flatness, wettability, surface energy, etc., can be determined by fluorine, Group S ⁵ selected from substituted or halogenated heteroatom-optionally substituted groups such as branched or unbranched, branched or straight aliphatic and aromatic groups, in the polymer backbone. These properties, especially surface energy, are known to greatly influence the alignment direction and anchoring strength of the liquid crystal.

Include groups described before as the alcohol, and the spacer L - S ⁵ side-typical examples of groups is perfluorinated, and fluorinated C ₁ -C _18, such as - alkyl, such as C ₄ -C ₁₂ - alkyl.

For example, when the S ⁵ side-group is an alkyl chain, the T _g of the polymer generally decreases in proportion to the length of the alkyl chain. On the other hand, when the S ⁵ side-group is an aryl group, the T _g of the polymer generally increases.

A part of the repeating unit, the side with the prominent shape anisotropy as described above - in the polymer of the invention is functionalized by the groups S ^1, the polymer is also a side-repeat that is screen-based operation by S ⁵ units . For such polymers, the ratio of S ¹ to S ⁵ ranges from 1: 100 to 100: 1, typically from about 1: 1 to 1:20. It should be understood, however, that the polymers of the present invention with S ¹ or S ⁵ side-only can be preferably used in some applications.

In an embodiment of the present invention, the ionic motion inhibition S ⁶ group can be used in the alignment layer to lower the concentration of mobile ions in the LC bulk material, thereby lowering the conductivity of the LC bulk material. Ionic motion inhibiting groups are nonionic polar groups, typically attracting ions. Examples of ionic motion inhibiting groups include materials commonly known as ion traps such as hydroxyl groups and other coronands.

In embodiments of the present invention, the polymer in the composition of the present invention may be, for example, an internal crosslinking linking two repeating units in the same polymer backbone or an external crosslinking linking two separate polymer backbones , Can be crosslinked by a crosslinking group connecting two separate repeating units, wherein at least one of the two repeating units represents the polymer of the present invention. Crosslinking groups that link one polymer of the present invention to another polymer may also be used.

In the present invention, cross-linking is preferably carried out by photo-reactive groups such as those described below, but may also be carried out using thermally induced reactions and any reactive groups attached to the polymer.

Copolymers of the present invention is reactive, preferably light may include a group S ^7-reactive side. Reactive side-groups can be used to anchor the alignment of the alignment layer obtained to make it less sensitive to temperature-induced changes.

The photo-reactive side-groups with shape-anisotropy can be aligned with the orientation desired to be obtained, for example, by irradiation with linearly polarized light. That is, light can be used to dimerize / polymerize only those groups that have a particular orientation relative to that of polarized light, thereby obtaining the desired orientation of such groups in the polymer.

This may have the advantage that the photo-alignment can often align and cross-link the material, so that the alignment orientation can be a one-step process that simultaneously achieves higher thermal stability. The light-orientation also has the advantage of not introducing dust, scratches or electrostatic discharge which can be caused by the rubbing method used today. Also, it is easy to control accurately, resulting in a high yield.

The dimerization / polymerization of reactive side-groups can be achieved between two reactive side-groups attached to one and the same polymer backbone, or between two reactive side-groups attached to a separate polymer backbone.

Examples that can be listed as photo-reactive groups with geometric anisotropy include, but are not limited to, chalcone, coumarin, and cinnamoic.

The copolymer of the present invention may comprise a light-responsive side-group S ⁸ .

The light-responsive side-groups with shape anisotropy can be aligned in a desired orientation, for example, by irradiation with linearly polarized light. For example, the side-groups may be oriented using light with a reactive group, and then the resulting orientation, having the same advantages as the light-reactive groups, may be irreversibly fixed with liquid crystal alignment using dimerization / polymerization as described above . In this case, the photoreactive group need not have shape anisotropy because the orientation can be carried out by a light responsive group having shape anisotropy.

Alternatively, the photo-responsive group can be oriented by light at an elevated temperature, and then the temperature is lowered to achieve reversible fixation of the orientation. Photo-responsive groups suitable for use in the present invention include, but are not limited to, azo-containing groups, stilbenes, and the like.

In addition, the photo-orientation of the polymer according to the invention can be achieved by photo-orientation of the polymer backbone using UV light irrespective of the presence of any light-responsive and / or photo-reactive side groups S7 have. The photo-orientation of such a polymer backbone is schematically illustrated in Fig. First, an alignment film material comprising at least one polymer according to the present invention is provided. The alignment film material may be coated on the substrate as described below. Next, in order to achieve photo-alignment of the polymer backbone, the alignment film material is illuminated with linearly polarized UV light having a wavelength in the range of 200 to 300 nm. For example, the UV light may have a wavelength of from 230 to 270 nm, such as about 250 nm.

The maleimide monomers functionalized by linkers and / or side groups as defined in the context of the present invention may be synthesized according to methods well known in the art.

An exemplary synthesis process is described in the Examples section below.

For example, maleic anhydride can be reacted with an amine to form the functionalized maleimide monomer.

Alternatively, the maleimide (with maleimide ring nitrogen attached to the hydrogen) can be reacted with an alcohol to form the functionalized maleimide.

A double-side liquid crystal device 100 is shown in Fig. 2, which includes a first substrate 101 and a second substrate 102 spaced apart from each other. A liquid crystal material 103 is inserted between the two substrates 101 and 102 in a space between the substrates 101 and 102.

On the first substrate 101, a surface-director alignment film 104 of the present invention in contact with the liquid crystal material 103 is provided.

Depending on the presence of the anchoring side-groups of the polymeric phase of the present invention, the surface-director alignment layer 104 may be chemically bonded to the substrate 101.

The surface-director alignment film 104 includes at least one polymer of the present invention as described above so that the surface-director alignment film 104 is at least in contact with the liquid crystal material 103). ≪ / RTI >

Those skilled in the art will recognize that the liquid crystal device 100 of the present invention may include means for obtaining an electric field in the liquid crystal material 103. [ The change in the electric field typically affects the switching of the liquid crystal material. For example, such means may be represented by a pair of electrodes. 1, the first electrode 105 is disposed between the alignment layer 104 and the substrate 101, and the second electrode 107 is disposed on the second substrate 102. In the embodiment shown in FIG.

The surface-director alignment film 104 will induce homeotropic alignment of the surface-director of the liquid crystal material 103.

The second alignment layer 106 is disposed between the second substrate 102 and the liquid crystal material 103. This second alignment layer may also comprise the polymer of the present invention, or alternatively it may be of another kind of alignment film material.

Example

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described with reference to the following examples which illustrate the present invention in more detail. It is to be understood that the embodiments are provided to illustrate the invention and are not intended to limit the scope of the invention. The scope of the invention is limited only by the appended claims.

Except for the following materials, commercially available compounds are used as obtained: i) N-vinyl-pyrrolidone (NVP) and N-vinyl-caprolactam are used for the removal of the added stabilizer Before passing through aluminum oxide. ii) When dry THF is required, conventional THF is dried by passing it through aluminum oxide prior to use. For the drying of THF and purification of NVP, aluminum oxide activated neutral Brockmann 1, 58 Å, (CAS 1344-28-1) was used.

In all of the following examples, standard reactions well known to those skilled in the art for the preparation of polymers were utilized. Polymeric alignment materials can be prepared, for example, by copolymerization of the functionalized maleimide with N-vinylpyrrolidone. The preparation of these materials and the side-groups used is given below.

N- Dodecylmaleimide ( VIII ): Dodecylamine is dissolved in chloroform and an equivalent amount of maleic anhydride is added. After stirring at room temperature for 2 hours, the solvent is removed. The formed amic acid is used in the untreated form, dissolved in acetic anhydride, and an equal amount of sodium acetate is added. The mixture is refluxed for 6-8 hours and then the solvent is removed under vacuum. The residue is passed through a short silica gel column using 2/1 or 4/1 petroleum ether / ethyl acetate as the eluent. This process proceeds well for amines ranging from octyl to at least hexadecyl. Since the imide from hexyl and shorter is the liquid, more careful chromatography should be performed using the same conditions as above. Yield: 41%. NMR (CDCl _3): δ, pattern quantum number; 0.85, t, 3; 1.25, m; 2.6, m, 2; 3.5, t, 2; 6.7, s, 2.

Maleimide XI : 4.2 g (9.55 mmol) II, 0.93 g (9.55 mmol) maleimide, and 2.5 g (9.55 mmol) triphenylphosphine were dissolved in 40 ml dry tetrahydrofuran. 9.55 mmol (4.4 ml, 40% solution in toluene) of diethyl azodicarboxylate (DEAD) was added dropwise to the reaction mixture. The mixture was stirred at room temperature for 3 hours and evaporated to dryness. The residue was taken up in 2/1 petroleum ether / ethyl acetate and purified by chromatography on silica gel. Yield: 2.8 g 56%. NMR (CDCl _3): δ, pattern quantum number; 1.0, t, 3; 1.1-1.6 3 m, about 20; 1.8, m, 4; 3.5, t, 2; 4, t, 2; 4.4, t, 2; 6.7, s, 2; 7.0, d, 2; 7.6, 2d, 4; 8.1, d, 2.

Maleimide XIII : 6.5 g (13 mmol) IX, 1.26 g (13 mmol) maleimide, and 3.4 g (13 mmol) triphenylphosphine were dissolved in 100 ml dry tetrahydrofuran. 13 mmol (5.9 ml, 40% solution in toluene) of diethyl azodicarboxylate was added dropwise to the reaction mixture. The mixture was stirred at room temperature for 3 hours and evaporated to dryness. The residue was taken up in toluene / ethyl acetate 4/1 and purified by chromatography on silica gel. Yield: 4.0 g 53%. NMR (CDCl _3): δ, pattern quantum number; 0.9, t, 3; 1.1-1.6, 3m; 1.8, m, 4; 3.5, t, 2; 3.9, t, 2; 4.1, t, 2; 6.7, s, 2; 6.9, 2d, 4; 7.1, d, 2; 8.1, d, 2.

Maleimide XIV : 1.5 g (4 mmol) XIV, 0.40 g (4.1 mmol) maleimide and 1.13 g (4.1 mmol) triphenylphosphine were dissolved in 20 ml dry THF and 0.72 mmol (4.1 mmol) diethyl azodicarboxylate 2.19M solution. The reaction mixture was stirred at room temperature for 5 hours. The solvent was removed and the residue was refluxed in petroleum ether / ethyl acetate 2/1 and filtered at high temperature. The solvent was removed under vacuum and the residue was recrystallized from methanol to give a contaminated product.

Chromatography using petroleum ether / ethyl acetate 2/1 as the eluent gave a pure product of low yield due to loss during the recrystallization experiment. Yield: 0.3 g 0.6 mmol, 17%. NMR (CDCl _3): δ, pattern quantum number; 0.9, t, 3; 1.3-1.7, 3m, 12; 1.8, m, 4; 3.6, t, 2; 4, t, 4; 6.7, s, 2; 6.93, m, 4; 7.45, m, 4.

Generally, one of the two methods described in Scheme IV is used for the monomers. Other well known methods of making maleimides may be used.

A third method for preparing maleimide is shown in Scheme VI above. All materials were used as supplied by the supplier. All steps were carried out under a nitrogen atmosphere.

Ethyl aniline (10 mmol, 1220 mg) was added while stirring a solution of maleic anhydride (10 mmol, 980 mg) in 30 ml of toluene with stirring. The solution was stirred for 1 hour while the precipitate was formed. It was added ZnBr ₂ (10mmol, 2250mg), followed by heating the solution to 80 ℃. At high temperature, hexamethyldisilazane (HMDS) (14 mmol, 2250 mg) was added dropwise over 15 minutes with a syringe, because adding too quickly may result in the formation of char. After heating for 1 hour, the reaction mixture was poured into 180 ml of 0.5% HCl and the aqueous phase was extracted twice with 150 ml of EtAc. The organic phase was then washed sequentially with 150 ml saturated NaHCO ₃ and brine. The solution was dried and purified by chromatography using toluene / EtAc 19/1 as the eluent. The yield was 66%.

Polymer  synthesis

Example  1: Vertical alignment ( VA ) Copolymer

(225 mg) of maleimide XIII, 1.6 mmol (424 mg) of N-dodecylmaleimide VIII, 2.0 mmol (222 mg) of NVP purified by passing through aluminum oxide and 2,2'- azobis (2-methylpropionitrile ) (AIBN) (19 mg) were dissolved in 10 ml of benzene in a round bottom flask and the flask was sealed with a rubber septum. Vacuum was applied through the diaphragm with an injection needle, and then nitrogen was injected. The vacuum-nitrogen injection cycle was repeated 10 times to evacuate the oxygen in the flask. The flask was heated in an oil bath heated to 60 < 0 > C. After 15 hours, the solution was poured into methanol and the polymer formed was precipitated. The polymer was reprecipitated from chloroform twice in methanol and finally precipitated once from chloroform with a 1/3 mixture of acetone / methanol. The solvent was decanted and pure methanol was added. Finally, the polymer was placed in a bottle and heated on a hot plate to remove residual solvent. The last traces of solvent were removed by heating the polymer to 60 [deg.] C in a vacuum oven for 2 hours. Yield: 0.7 g, 80%. NMR (CDCl _3): δ, pattern; 0.9, t; 1-5 side-to-base signal at the top of wide main chain signal; 6.9, 2d; 7.1, d; 8.1, d. The polymer composition for the mesogen / alkyl ratio was determined using methyl and aromatic signals in ¹ H NMR and found to be 1 / 4.2. This means that 19.2% of the side-groups are mesogenic when they ignore the pyrrolidone group.

This material was laminated as an alignment layer on the inner surface of the glass substrate of the sandwich cell prepared according to the process described. The cell is filled with a nematic liquid crystal MLC 6608 with negative dielectric anisotropy (DELTA epsilon < 0) and is first examined with a polarizing microscope to clarify the sort of alignment of the liquid crystal enhanced by the alignment layer. The alignment observed in this cell was homeotropic, that is, along the substrate normal. The pre-tilt angle in the desired direction of liquid crystal alignment from the substrate normal was then measured using a Muller matrix spectrometer. When the alignment layer is mechanically rubbed, a small pretilt of less than one degree is obtained.

The alignment layer also exhibited good thermal stability.

Example  2: Copolymer XXVI

VA Copolymer: 0.5 mmol (331 mg) of mesogenic maleimide XIII, 0.5 mmol (228 mg) of perfluorohexylpropylmaleimide XXV, 1.5 mmol (400 mg) of dodecylmaleimide, 2.5 mmol , And 0.15 mmol (25 mg) of 2,2'-azobis (2-methylpropionitrile) (AIBN) were dissolved in 25 ml of benzene. Polymerization was carried out in an oil bath at 60 캜 for 40 hours. The final polymer XXVI was obtained by re-precipitation from methanol in chloroform to methanol three times and once in methanol / acetone 2/1.

This material was tested in the same manner as in Example 1 to obtain similar yields and properties. The material exhibits a vertical orientation with a slow filling rate due to the low surface energy of the fluorinated groups.

Example  3: High Tg of VA Polymer

Azobis (2-methylpropionitrile) (AIBN (2-methylpropionitrile)) was prepared by reacting 0.40 mmol (180 mg) of maleimide XIII, 1.6 mmol ) (19 mg) were dissolved in 10 ml of benzene. The mixture was polymerized and carried out according to the procedure described in Example 1. Yield: 0.26 g, 38%. NMR (CDCl _3): δ, pattern; 0.9, bs; 1.1-5 side-base signal at the top of the wide backbone signal; 6.9, bs; 7.0-7.6, bs.

Due to the solid side-tile mesogens, the glass transition temperature can be increased compared to the case of the soft alkane chain. This material exhibits a Tg of about 200 ° C. This material was laminated as an alignment layer on the inner surface of the glass substrate of the sandwich cell prepared according to the process described. This cell is filled with a nematic liquid crystal MLC 6608 with negative dielectric anisotropy (DELTA epsilon < 0) and is first examined with a polarizing microscope to clarify the sort of alignment of the liquid crystal enhanced by the alignment layer. The alignment observed in this cell was homeotropic, that is, along the substrate normal. The pretilt angle in the preferred direction of liquid crystal alignment from the substrate normal was then measured using a Muller matrix spectrometer. When the alignment layer is mechanically rubbed, a pre-tilt is obtained.

The alignment layer also exhibited good thermal stability.

Example  4

N-vinyl epsilon -caprolactam XXX VA copolymer: 0.4 mmol (225 mg) of maleimide XIII, 1.6 mmol (424 mg) of N-dodecylmaleimide VIII, 2.0 mmol (278 mg) 0.12 mmol (19 mg) of 2'-azobis (2-methylpropionitrile) (AIBN) was dissolved in 10 ml of benzene in a round bottom flask and the flask was sealed with a rubber septum. Vacuum was applied through the diaphragm with an injection needle, and then nitrogen was injected. The vacuum-nitrogen injection cycle was repeated 10 times to evacuate the oxygen in the flask. The flask was heated in an oil bath heated to 60 < 0 > C. After 15 hours, the solution was poured into methanol and the polymer formed was precipitated. The polymer was reprecipitated from chloroform twice in methanol and finally one time from acetone / methanol 1/3 mixture from chloroform. The solvent was decanted and pure methanol was added. Finally, the polymer was placed in a bottle and heated on a hot plate to remove residual solvent. The last trace of solvent was removed by heating the polymer to 70 캜 in a vacuum oven for 4 hours. Yield: 0.75 g, 81%.

This material was laminated as an alignment layer on the inner surface of the glass substrate of the sandwich cell prepared according to the process described. The cell is filled with a nematic liquid crystal MLC 6608 with negative dielectric anisotropy (DELTA epsilon < 0) and is first examined with a polarizing microscope to clarify the sort of alignment of the liquid crystal enhanced by the alignment layer. The alignment observed in this cell was homeotropic, that is, along the substrate normal. The pretilt angle in the preferred direction of liquid crystal alignment from the substrate normal was then measured using a Muller matrix spectrometer. When the alignment layer is mechanically rubbed, a small pretilt of less than one degree is obtained.

Example  5: Planar alignment ( PA ) Copolymer

(265 mg) of maleimide XVI, 1.6 mmol (334 mg) of N-octyl maleimide, 2.0 mmol (222 mg) of NVP purified by passing through aluminum oxide and 2,2'-azobis (2-methylpropionitrile) AIBN) (19 mg) were dissolved in 10 ml of benzene. Polymerization and work-up were carried out according to the preparation method of Example 1. [ Yield: 0.66 g, 80%. NMR (CDCl _3): δ, pattern; 0.9, t; 1-5 side-to-base signal at the top of wide main chain signal; 6.5, d; 6.9, d; 7.1, d; 8.0, d. The polymer composition for the mesogen / alkyl ratio was determined using methyl and aromatic signals in ¹ H NMR and found to be 1 / 1.8. This means that 36% of the side-groups are mesogens when ignoring the pyrrolidone group.

This material was laminated as an alignment layer on the inner surface of the glass substrate of the sandwich cell prepared according to the process described. The cell was filled with a nematic liquid crystal MLC 6873-100 with positive dielectric anisotropy (DELTA epsilon> 0) and was first examined with a polarizing microscope to clarify the type of alignment of the liquid crystal enhanced by the alignment layer. The alignment observed in this cell was homogeneous, i.e. essentially parallel to the substrate. The alignment layer also exhibited good thermal stability.

Example  6

0.1 mmol (67 mg) of maleimide XVII, 0.4 mmol (1.6 mg) of N-hexyl maleimide, 0.5 mmol (54 mg) of NVP purified by passing through aluminum oxide and 2,2'-azobis (2-methylpropionitrile) 0.03 mmol (5 mg) of AIBN were dissolved in 20 ml of benzene in a round bottom flask and the flask was sealed with a rubber septum. Vacuum was applied through the diaphragm with an injection needle, and then nitrogen was injected. The vacuum-nitrogen injection cycle was repeated 10 times to evacuate the oxygen in the flask. The flask was heated in an oil bath heated to 60 < 0 > C. After 17 hours, most of the benzene was evaporated in a rotary evaporator, the solution was poured into methanol and the polymer formed was precipitated. The polymer was reprecipitated from chloroform twice in methanol. Finally, the polymer XXXIV was bottled and the residual solvent was removed at room temperature. Yield: 0.10 g, 44%.

This material was laminated as an alignment layer on the inner surface of the glass substrate of the sandwich cell prepared according to the process described. However, instead of rubbing the sample, the sample was oriented by placing it at 5 mW / cm < 2 > for 15 minutes under linearly polarized light. The cell was filled with a nematic liquid crystal MLC 6873-100 with positive dielectric anisotropy (DELTA epsilon> 0) and was first examined with a polarizing microscope to clarify the type of alignment of the liquid crystal enhanced by the alignment layer. The alignment observed in this cell was homogeneous, i.e. essentially parallel to the substrate.

Example  7: As a monomer XVIII Lt; / RTI > Example  VA < / RTI > Copolymer .

(2-methylpropionitrile) (2-methylpropionitrile) were prepared by reacting 0.2 mmol (118 mg) of maleimide XVIII, 1.8 mmol (477 mg) of N-octyl maleimide, 2.0 mmol AIBN) (19 mg) were dissolved in 10 ml of benzene. Polymerization and work-up were carried out according to the preparation method of Example 1. [ Yield: 0.66 g, 81%, cinnamic ester 5% dodecyl group 95%. NMR (CDCl _3): δ, pattern; 0.9, t; 1-5 wide signal, 6.5, d; 6.9, d; 7.08, d; 7.5, d; 7.8, d.

This material was laminated as an alignment layer on the inner surface of the glass substrate of the sandwich cell prepared according to the process described. The cell is filled with a nematic liquid crystal MLC 6608 with negative dielectric anisotropy (DELTA epsilon < 0) and is first examined with a polarizing microscope to clarify the sort of alignment of the liquid crystal enhanced by the alignment layer. The alignment observed in this cell was homeotropic, that is, along the substrate normal. The alignment layer also exhibited good thermal stability.

Example  8: Alkyl  chain

(1.0 mmol) of N-octylmaleimide, 111 mg (1.0 mmol) of NVP purified through passing through aluminum oxide and 9.8 mg (0.12 mmol) of 2,2'-azobis (2-methylpropionitrile) Benzene < / RTI > Polymerization and work-up were carried out according to the production method of the VA copolymer. Yield: 0.23 g, 72%. NMR (CDCl _3): pattern; 0.85, s; 1.2, s; 1.5, s; 1.6-4.5 Wide signal.

This material was laminated as an alignment layer on the inner surface of the glass substrate of the sandwich cell prepared according to the process described. The cell was filled with a nematic liquid crystal MLC 6873-100 with positive dielectric anisotropy (DELTA epsilon> 0) and was first examined with a polarizing microscope to clarify the type of alignment of the liquid crystal enhanced by the alignment layer. The alignment observed in this cell varied with the rubbing and thermal conditions. Since it has only an alkyl chain, it has low anchoring strength and sensitivity alignment.

Example  9

Since it does not contain mesogens, the material generally has a lower anchoring strength and a relatively more sensitive alignment.

(0.44 mmol) of the fluorinated chain, 184 mg (0.88 mmol) of the alkyl chain, 146 mg (1.32 mmol) of N-vinylpyrrolidone purified through passage through active aluminum oxide and 13 mg of AIBN were dissolved in 13 ml of benzene. Polymerization and work-up were carried out according to the method of Example 1. Yield: 180 mg, 34%.

Cells were made in the same manner as in Example 8 using the above materials. The cell exhibits very poor wetting properties relative to the polymer XXXVI due to the very low surface energy due to the fluorinated chains.

Example  10

Copolymers with variable alkane chain length. 8 + 12 alkane chains.

(209 mg) of N-octylmaleimide, 1 mmol (265 mg) of N-dodecylmaleimide, 2 mmol of NVP purified by passing through aluminum oxide (222 mg) and 2,2 'azobis (2-methylpropionitrile) ) (19 mg) were dissolved in 10 ml of benzene. Polymerization and work-up were carried out according to the preparation method of Example 1. [ Yield: 0.55 g, 79%.

Cells were made in the same manner as in Example 1 using the above materials. The cell represents homeotropic alignment. By incorporating an even longer alkane as compared to Example 8, the VA stability of the material is increased and the material exhibits homeotropic alignment when tested using the method described in Example 8. [ The alignment is more dependent on rubbing and temperature than when the mesogens are used, as in Example 1.

Example  11

1 mmol of N-butyl maleimide (153 mg), 1 mmol (111 mg) of NVP purified through passage through aluminum oxide and 0.06 mmol (9.7 mg) of 2,2 'azobis (2-methylpropionitrile) (AIBN) . Polymerization and work-up were carried out according to the preparation method of Example 1. [ Yield: 0.1 g, 38%.

In contrast to the preceding embodiments, when short alkyl chains are used, the PA enhancing properties are increased and the butyl maleimide based copolymers exhibit PA alignment and higher glass transition temperatures. Cells were made in the same manner as in Example 8 using the above materials. The cell represents a planar alignment with a rubbing-induced pretilt.

When oriented by UV light as described in general method c2 below, the material also exhibits good and uniform planar alignment.

Example  12

PA Copolymer : 1 mmol (201 mg) of ethyl-phenyl-maleimide XXII, 0.06 mmol (10 mg) of 1 mmol of NVP purified by passing through aluminum oxide and 2,2 'azobis (2-methylpropionitrile) Was dissolved in 10 ml of benzene. The polymerization was carried out overnight in an oil bath at 60 占 폚. Reprecipitation was carried out three times in methanol from several ml of chloroform to purify. _{Yield: 0.180g, NMR (CDCl 3)} δ, pattern; Quantum number; 1.1-1.2 wide triple bonds from terminal ethyl carbon; 1-5 side-to-base signal at the top of wide main chain signal; 6.9-7.35; A broad peak from the aromatic proton (broad because it is close to the polymer backbone);

This material was laminated as an alignment layer on the inner surface of the glass substrate of the sandwich cell prepared according to the process described. The cell was filled with a nematic liquid crystal MLC 6873-100 with positive dielectric anisotropy (DELTA epsilon> 0) and was first examined with a polarizing microscope to clarify the type of alignment of the liquid crystal enhanced by the alignment layer. The alignment observed in this cell was homogeneous, i.e. essentially parallel to the substrate. The alignment layer also exhibited good thermal stability.

This material is soluble in PGMEA and NMP. As a general "extended" skeleton with a high glass transition temperature and planar alignment, this appears to be a good choice for adding other groups as an alternative to the alkane chain.

When oriented by UV light as described in general method c2 below, the material also exhibits good and uniform planar alignment.

Example  13

PA Copolymer : 1 mmol (201 mg) of ethylphenylmaleimide, 0.5 mmol (175 mg) of 2-hexyloxybiphenylmaleimide, 1.5 mmol (166 mg) of NVP purified through passage through aluminum oxide and 2,2'azobis Propionitrile) (AIBN) (15 mg) was dissolved in 15 ml of benzene. Polymerization was carried out in an oil bath at 60 캜 for 22 hours. Reprecipitation was carried out three times in methanol from several ml of chloroform to purify. The product is soluble in NMP and PGMEA.

This material was laminated as an alignment layer on the inner surface of the glass substrate of the sandwich cell prepared according to the process described. The cell was filled with a nematic liquid crystal MLC 6873-100 with positive dielectric anisotropy (DELTA epsilon> 0) and was first examined with a polarizing microscope to clarify the type of alignment of the liquid crystal enhanced by the alignment layer. The alignment observed in this cell was homogeneous, i.e. essentially parallel to the substrate normal, but had a very sensitive slope for rubbing conditions. When oriented by UV light as described in general method c2 below, the material exhibits good and uniform planar alignment.

Example  14

Maleimide copolymer functionalized with hydroxyl: 1.0 mmol (197 mg) of 6-hydroxyhexyl maleimide, 1.0 mmol (207 mg) of N-octyl maleimide, 2.0 mmol (222 mg) of N-vinylpyrrolidone, 0.12 mmol (19 mg) of azobis (2-methylpropionitrile) (AIBN) was dissolved in a mixture of 5 ml of benzene and 5 ml of ethanol. The mixture was polymerized at 60 DEG C for 15 hours. The polymer was precipitated in diethyl ether and reprecipitated once from the benzene / ethanol in ether. Yield: 0.29 g. NMR (CDCl ₃₎ δ, pattern; Quantum number; 0.75, bs; 1.35-1.75, two wide signals and shoulder; 1.8-4.5 wide signals, including signals not separated from the imine nitrogen and the methylene proton adjacent to the alcohol at 3.4 and 3.6, respectively.

100 mg of the photocopolymer from the functionalization, 50 mg (0.20 mmol) of 4-hexyloxycinnamic acid (XLIV), 10 ml of methylene chloride and a catalytic amount of 4-methylaminopyridine corresponding to about 0.16 mmol of the OH group of the resulting copolymer XLIII , And stirred until all components were dissolved. The mixture was cooled in an ice bath and 50 mg (0.24 mmol) of DCC (dicyclohexylcarbamide) was dissolved in a small amount of methylene chloride and added. The reaction mixture was stirred at room temperature overnight. The formed urea precipitate was filtered off and most of the solvent was removed in vacuo. The polymer tried to settle in methanol but failed. The solvent was removed in vacuo, methanol was added to the residue and heated to reflux. The solvent was decanted at a high temperature and the above process was repeated twice. This work-up method required purification, but a low yield of polymer XLV of 40 mg was obtained. NMR (CDCl ₃₎ δ, pattern; 0.85, t; A 1.1-5 side group signal on top of the broad main chain signal, the remaining -CH ₂ -OH appears as a shoulder on N-CH ₂ ; 6.25. d '6.85, d; 7.45, d; 7.6, d. The ratio of cinnamic ester / alkyl groups was found to be 1 / 1.5, and the conversion of hydroxyl groups to esters was about 66%.

This material was laminated as an alignment layer on the inner surface of the glass substrate of the sandwich cell prepared according to the process described. The cell was filled with a nematic liquid crystal MLC 6873-100 with positive dielectric anisotropy (DELTA epsilon> 0) and was first examined with a polarizing microscope to clarify the type of alignment of the liquid crystal enhanced by the alignment layer. The alignment observed in this cell was homogeneous, i.e. along the substrate. The alignment also showed good thermal stability and could be photo-oriented by UV light. This example illustrates one of a very wide variety of alternative methods for preparing side-chain maleimide / vinylcaprolactam copolymers by functionalization.

General Manufacturing Method of Liquid Crystal Cell

a. Polymer  Preparation of solution

An alignment layer made from the copolymer of the present invention is laminated as a 0.2% to 5% solution of the copolymer in a solvent such as NMP and PGMEA. The copolymer solution is first filtered through a 0.2 mu m filter.

b. Copolymer  Lamination

The copolymer solution is applied, for example, by a spinner (at a rate of 3,000 rps) onto the surface of a clean glass substrate with a pre-fabricated transparent conductive electrode made of ITO. The substrate is then held at room temperature for a suitable period of time to remove the solvent. This process may be shorter if the substrate is held at elevated temperature (80-120 < 0 > C).

c1 . Mechanical treatment

A substrate covered with an alignment layer comprising a copolymer of the present invention, for example a layer promoting planar alignment, may be mechanically rubbed along a particular direction. In the case of an alignment layer made of a copolymer that promotes vertical orientation, rubbing may not be necessary.

c2 . Copolymer  Light-orientation

The UV illumination of the experimental substrate covered with the light-sensitive copolymer was carried out in a standard USHIO apparatus providing linearly polarized light of 5mW / cm < 2 > from a high pressure mercury UV lamp without a UV filter. The above photosensitive polymer was laminated on a glass substrate by spin coating from a 1 wt% solution of the polymer in PGMEA. Subsequently, the substrate was exposed to V light incident normal. The irradiation time was chosen to be 15 minutes.

d. Cell Manufacturing

Experimental cells are composed of two substrates which are assembled in parallel with each other and have a spacing of several 占 퐉. The distance between the substrates is typically fixed by glass or polymer spacers. The substrate faces each other with its surface covered by the alignment layer. The cell gap formed by the substrate and the substrate is filled with liquid crystal by a capillary force.

e. Copolymer  Evaluation of alignment characteristics

An evaluation of the alignment of the liquid crystals in the laboratory cell enhanced by the alignment layer made of the inventive copolymer is performed using the following:

ㆍ Optical polarization microscopy

Muller matrix spectrometer (I. Dah., Meas. Sci. Technol. 12, 1938, 2001)

Taken together, the polymers of the present invention are described herein as being suitable for use as an alignment layer or as an alignment layer for a liquid crystal device.

Those skilled in the art will recognize that the invention is not limited to the preferred embodiments described above. On the contrary, various modifications and variations are possible within the scope of the appended claims.

101 substrate, 102 substrate, 103 liquid crystal material, 104 alignment layer, 105 first electrode, 106 second alignment layer, 107 second electrode

Claims (20)

As a polymer for use in a surface-director alignment layer,
The polymer is a copolymer comprising at least one repeating unit of maleimide and its derivatives and at least one repeating unit of N-vinyl lactam and its derivatives,
Wherein at least a portion of at least one of the repeat units of the maleimide and derivatives thereof is functionalized by a pendant side-group S ¹ having an anisotropy and the pendant side-group S ¹ is a meso A generic side-group,
The polymer, pendant side-groups S ^5-maleimide, and further comprising at least one repeating unit of a derivative thereof, and containing the pendant side-groups S ⁵ is optionally halogenated, or a branched or straight-chain type aliphatic and aromatic groups , A polyether, a siloxane, or an alcohol. The method according to claim 1,
At least a portion of at least one repeating unit of the maleimide and derivatives thereof is selected from the group consisting of methyl; ethyl; Anchoring side-group S ⁴ ; Ion motion inhibition side-group S ⁶ ; Reactive side-group S ⁷ ; And a side-group S ^x group selected from the light-responsive side-group S ⁸ , or a hydrogen atom,
The anchoring side group S ⁴ represents a C ₂ to C ₂₀ hydrocarbon chain having a functional group containing an amino, hydroxy, isocyano, or glycidyl group,
The ion-motion-inhibiting side-group S ⁶ includes a hydroxyl group or a coronand,
Said reactive side-group S ⁷ comprises chalcone, coumarin, or cinnamoic,
The light-responsive side-group S ⁸ comprises an azo-containing group or stilbene. The method according to claim 1,
Wherein the amount of the maleimide and N-vinyl lactam repeating units is at least 50% of the repeating units of the polymer backbone. The method according to claim 1,
Wherein the amount of the maleimide and N-vinyl lactam repeating units is at least 75% of the repeating units of the polymer backbone. The method according to claim 1,
Wherein the amount of the maleimide and N-vinyl lactam repeating units is 90% or more of the repeating units of the polymer backbone. The method according to claim 1,
Wherein the ratio of maleimide to N-vinyl lactam units in the polymer backbone is from 1:10 to 10: 1. The method according to claim 1,
Wherein the ratio of maleimide to N-vinyl lactam units in the polymer backbone is from 1: 2 to 2: 1. The method according to claim 1,
Wherein the ratio between the maleimide and the N-vinyl lactam unit in the polymer backbone is 1: 1. The method according to claim 1,
Wherein the N-vinyl lactam is selected from the group consisting of N-vinyl pyrrolidone, N-vinyl piperidone and N-vinyl caprolactam. 3. The method of claim 2,
Wherein the polymer comprises
Anchoring side-repeating units functionalized by group S ⁴ ;
A repetitive unit functionalized by an ionic motion inhibiting side-group S ⁶ ;
A repeating unit functionalized by a reactive side-group S ⁷ ; And
The light-responsive side-repeating units functionalized by S ⁸
≪ / RTI > The method according to claim 1,
A polymer comprising a crosslinker. The method according to claim 1,
Wherein at least a portion of at least one of the side-groups and hydrogen atoms is attached to the repeating unit through maleimide-nitrogen. 3. The method of claim 2,
The side-group at least one of S ^1, and S ^x is attached to the repeating unit via a spacer group L, wherein L is a spacer group, C ₅ -C, a polymer containing ₁₅ alkyl or alkyloxy chain. The method according to claim 1,
Said side-group S ¹ with shape-anisotropy comprises a side-group S ^1a which is a mesogenic side-group inducing a planar alignment of the liquid crystal material and a side-group S ^{1 which} is a mesogenic side-group inducing the vertical orientation of the liquid crystal material ^1b . A surface-director alignment film comprising at least one polymer deposited on a solid substrate,
The polymer is a copolymer comprising at least one repeating unit of maleimide and its derivatives and at least one repeating unit of N-vinyl lactam and its derivatives,
At least a portion of at least one of the repeating units of the maleimide and its derivatives is functionalized by a pendant side-group S ¹ having a shape anisotropy, the pendant side-group S ¹ is a mesogenic side-
At least a portion of at least one of the repeating units of the maleimide and derivatives thereof comprises a pendant side-group S ⁵ selected from aliphatic and aromatic groups, polyether, siloxane or alcohol, optionally halogenated, branched or straight- Surface-director alignment layer. 16. The method of claim 15,
S _x , or a maleimide functionalized with a hydrogen atom and derivatives thereof,
The S _x group is selected from the group consisting of methyl; ethyl; Anchoring side-machine S ⁴ ; Ion motion inhibition side-group S ⁶ ; Reactive side-group S ⁷ ; And a side-group selected from the light-responsive side-group S ⁸ ,
The anchoring side group S ⁴ represents a C ₂ to C ₂₀ hydrocarbon chain having a functional group containing an amino, hydroxy, isocyano, or glycidyl group,
The ion-motion-inhibiting side-group S ⁶ includes a hydroxyl group or a coronand,
Said reactive side-group S ⁷ comprises chalcone, coumarin, or cinnamoyl,
The light-responsive side-group S ⁸ comprises an azo-containing group or stilbene. 17. The method according to claim 15 or 16,
A surface-director alignment film comprising a polymer according to any one of claims 3 to 14. A liquid crystal device comprising: at least one substrate; a liquid crystal bulk; and a surface-director alignment film arranged between the at least one substrate and the liquid crystal bulk and in contact with the surface of the liquid crystal bulk,
Wherein the surface-director alignment film is as defined in claim 15 or 16. 16. The method of claim 15,
Liquid crystal device. A liquid crystal display device comprising: a first substrate and a second substrate interposed therebetween;
A first surface-director alignment film is arranged between the first substrate and the liquid crystal bulk and is in contact with the surface of the liquid crystal bulk;
A second surface-director alignment film is arranged between the second substrate and the liquid crystal bulk and is in contact with the surface of the liquid crystal bulk;
Wherein at least one of said first and said second surface-director alignment films is as set forth in claim 15 or claim 16. A method of optically-directing a surface-director alignment film material,
Providing a surface-director alignment film material according to claim 15 or 16; And
Directing the surface-director alignment film material with linearly polarized electromagnetic radiation having a wavelength in the range of 200 nm to 300 nm,
/ RTI >

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