WO2003082948A1 - A method of aligning polymer chains - Google Patents

Abstract

A hierarchical self-assembly in comb-shaped supramolecules of conjugated rod-like polymers and a novel concept to obtain the aligned solid state via cleaving side groups from the supramolecules are described. The supramolecules may consist of poly(2,5-pyridinediyl), acid dopants, and hydrogen bonded side chains. Films thereof are fluids even without an additional solvent and show thermotropic liquid crystallinity. They reveal exceptional degree of self-assembled order and the fluid state allows facile overall alignment yielding anisotropic opto-electronic properties, such as high dichroism and polarized emission. After alignment, cleavage of the side chains results in stable solid films with high optical anisotropy and enhanced photonic efficiency, such as improved photoluminescence quantum yield.

Description

A METHOD OF ALIGNING POLYMER CHAINS

Background of the Invention

Field of the Invention

The invention relates generally to highly organized polymeric materials obtainable by manipulation of assembled rod-like supramolecules. More particularly, the invention concerns efficient polarized light and high photoluminescence quantum yield based on aligned conjugated rod-like luminescent polymers. Further, the invention concerns a method of producing such materials.

Description of Related Art

Control of Molecular Packing and Macroscopic Overall Order in Conjugated Polymers

Manipulation of electro-optical properties in conjugated materials requires control of molecular packing and overall order[l]. Single crystals of oligomers [2-5] provide spectacular electronic properties but demand impractically sophisticated deposition techniques. Self- organization in solution-processed polymers, particularly in poly(alkylthiophene)s [6, 7], also yields local order with electronic characteristics approaching those of single crystals. However, a high overall order is exceedingly difficult to obtain due to coiling, a problem that could be overcome with the use of the rod-like polymers.

It is known in art that rigidity, high molecular weight and high molecular and overall order are crucial properties for inducing efficient opto-electronic properties to the conjugated molecules.

In the prior art, rod-like polymers have not been processed as such, i.e. they are infusible and it is either impossible to dissolve them in a solvent or the solvent options are highly limited due to limited mixing entropy of the rigid backbone.

Therefore, in the art, certain side-groups have been introduced to make the processing either possible or more practical. They are also needed in many standard alignment procedures of the rigid polymers. Also in the art, the covalently bonded side-groups necessary for facilitating processing of conjugated rod-like polymers or for inducing their self-assembly are inherently present, i.e. they cannot be removed after processing. Hence, the final product must be planned by taking into consideration the presence of such side-groups.

It would be highly advantageous to impart certain properties to the final oriented structure, which are currently difficult to achieve due to the nature of inherent, covalently bonded side- groups. Thus, the possibilities for designing the microstructures of aligned conjugated polymers are seriously limited.

This problem could be solved by using physical bonds instead of covalent side-groups. Self- assembled polymeric supramolecules can be aligned, thus providing tools to structure control from molecular level to the macroscopic order. In the art, physical bonding of non-conjugated polymers allows for cleavage, i.e. removal, of the side-groups of aligned polymeric supramolecules [8]. Nevertheless, the construction of supramolecules using rigid conjugated polymers [9, 10] is nontrivial due to their aggregation, limited solubility and demand for chemical stability in acidic solvents.

The crucial advantage of this method is demonstrated using photonic properties, polarized light and enhanced efficiency of rod-like conjugated material. Nevertheless, the concept is by no means limited to luminant materials, the same concept can be used to construct generic materials with less defects.

Without loss of generality, in the current work, rod-like poly(2,5-pyridinediyl) (PPY) is used as a model polymer for several reasons. It is conjugated and rod-like and it does not suffer from coiling, like e.g. polythiophenes, It has high photoluminescence quantum yield (PLQY) and it is an excellent electron transport material. Polypyridines [11] are also generally remarkably stable polymers with fascinating electronic properties [12]. Furthermore, PPY is among the simplest rod-like polymers, consisting of /rørα-coupled pyridyl rings; yet it contains specific sites needed to construct supramolecules. This makes it a very good model compound to demonstrate the present methodology.

PPY is soluble in formic acid 7JJ,3,5,5-hexafluoro-2-propanol and dichloroacetic acid or stronger inorganic acids, such as methanesulfonic acid. Formic acid forms neither well- defined lyotropic nor thermotropic liquid crystalline phase with PPY and is also very volatile. This practically prevents the well-defined alignment of PPY in the formic acid solution. Formic acid does not protonate PPY, whereas stronger acids do so. In particular, PPY can be complexed with sulfonic acids, which result in proton transfer [13]. The resulting counter-ions increase the solubility of the material, e.g. PPY protonated with dodecylbenzenesulfonic acid (DBSA) is soluble in chloroform [14].

When an acid molecule is amphiphilic, such as DBSA, the complexes consist of polymer backbone complexed with the DBSA molecules and they form lamellar self-organized structures with alternating polar and nonpolar layers. The complexation of PPY and DBSA to form PPY(DBSA)_X can be performed in dilute solution of formic acid that was removed by vacuum drying and heating [15].

It is known in the art that a self-organized plastized phase is formed for small x of PPY(DBSA)_X revealing strong X-ray diffraction peak at low scattering angles[15]. A surplus of Extra DBSA acts as a plastiziser and finally as a solvent. Because of the strong ionic attraction and strong repulsion, the mesomorphic structure exhibits no phase transitions until it is destroyed at ca. 300 °C, and, in particular, the highly connected acid molecules cannot be easily removed, i.e. cleaved, using heating and vacuum.

In the art, most sulfonic acids quench PL of PPY. Camphorsulfonic acid is the exception here, however [13].

Polarized Light Based on Aligned Conjugated Polymers

Polarized light is conventionally formed using isotropic light source and separate polarized filter. The natural disadvantage is that the intensity of the source is much reduced, 50 % or more, due to filter. Because polarized light is particularly needed as a backlight of light emitting diodes (LED:s) of mobile devices, the light sources should be as efficient as possible to prevent the use of too heavy batteries.

In contrast to conventional semiconductors, polymeric semiconductors consist of highly asymmetric rod-like molecules. When these molecules are highly aligned, they produce polarized light due to aligned transition dipole moments. Hence, no additional filters are needed, which naturally increases power efficiency. The lack of filters also itself reduces costs and weight. Organic materials allow also several additional advantages: They are also light and economic themselves, their preparation is easy, and they allow the full color spectrum due to chemical tuning.

The use of polymers in light emitting devices was first demonstrated by Richard Fried' s and Andrew P. Holmes' groups [18], whilst the first polarized LED made from a stretch-oriented conjugated polymer (alkyl-substituted polythiophene) was reported more recently by Olle Inganas' group [19].

Most of the aligned conjugated molecules show also other anisotropic opto-electronic properties, such as optical dichroism, i.e. they act as polarizers, independently of the emission. Nevertheless, they produce light by means of electroluminescence (EL) or photoluminescence (PL) only, when their electronic structure is suitable for that.

It is known in the prior art that when poly(2,5-pyridinediyl) is blended with a viscoelastic polymer, such as polyvinylalcohol (PNA), this blend can be stretched resulting in optical dichroism [16]. Also elsewhere in the art, this has been observed in stretch-oriented PPY PNA films [17] and it is ascribed to a larger delocalisation length in the ordered chains, which lie in the alignment direction.

There are four main approaches to produce polarized light based on aligned polymers: (i)

Mechanical alignment, (ii) alignment on specific 'rubbed' substrates, (iii) Langmuir-Blodgett (LB) techniques, and (iv) liquid crystalline self-assembly and the alignment of liquid crystals.

Two related concepts are (v) luminescent quest molecules in an aligned host matrix and polarizing excitonic energy transfer (EET) and (vi) circularly polarized emission. The state-of- art is summarized in a review by Martin Grell and Donald D. C. Bradley [20].

It should be noted that the present concepts deal with conjugated polymers or liquid crystalline (and here conjugated) polymers (LCP) in contrast to low molecular weight (LMW) liquid crystals (LC). i) In mechanical stretching or rubbing, a conjugated polymer is blended into the viscoelastic host polymer. When the blend is stretched, the rigid polymers are aligned. The main disadvantage is that the soft films tend to relax into an unoriented equilibrium state sooner or later. Strong rubbing also degrades the polymer. Alan Heeger's group was the first who patented a concept, wherein polymeric LED emits polarized light, and they also patented their fabrication method [21]. The material is PE-MEH-PPN blend prepared by mixing MEH- PPN with UHMW polyethylene in xylene. The solution is poured onto a glass surface where it forms a gel. Films are then tensile drawn, which results in alignment and polarized electroluminescence, when the substrate is a hole injector and when these layer are deposited by an electron injector. It is claimed that this is generally valid for any solution or gel processing.

ii) In prior art, rubbing of the substrate of the conjugated polymer film results in aligned structures [21]. The disadvantage of this approach is that the rubbing substrate is difficult to remove after alignment. The applicability of the method is also limited to specific substrates, such as polytetrafluoroethylene (PTFE), although generic substrates would allow more options in respect of transparency and tuning of work functions. [21] Lucent Technologies has been patented a process for fabricating polarized polymeric LED:s [22]. The friction transfer method is used and this method itself has been patented earlier[23]. In the general friction transfer method crystalline materials are grown on a highly oriented PTFE substrate deposited with second layer. The third, grown layer becomes oriented, i.e. the overlayer does not eliminate the orienting ability of the aligned PTFE chains. When the third layer is an aligned, rigid, conjugated luminant polymer (typically substituted PPP or PPN), the second layer (typically conjugated conducting polymer, such as PEDOT or PAΝI) is used as a charge transport layer in polarized LED. This construction is then deposited with another charge transport layer or different combinations of layers.

iii) Very specific 'shish-kebab-type' polymers align in LB deposition [24]. Due to instability, the films should be cross-linked after deposition, which is generally difficult to combine with alignment, and no such films are reported yet.

iv) In contrast to the stretched blended materials, the aligned state of liquid crystals represents their thermodynamic equilibrium. LMW LC:s can be aligned using flow, electric or magnetic field. Despite the fact that LMW LC:s are the key components in LC displays where the work as polarizers, there are only few examples, where they are used as a light source. In LCP:s, the flexible side chains are introduced to the conjugated backbone resulting in an LC phase. In contrast to the present concept, this is conventionally made using covalent bonding. Light emitting LCP:s can be aligned using e.g. mechanical methods. Martin Grell's and Donald Lupo's groups have been developing this methodology for LC polyfluorene, especially efficient luminant polymer [25]. Furthermore, Sony International and Max Planck Institut have patented a method of manufacturing polarized polymeric EL materials based on LC [26]. In the prior method, functional materials, typically a luminant LCP material with hole or/and electron injecting materials, are mixed with a polyimide. This composite is aligned by rubbing or by UN radiation or by air flow treatment. This structure is combined with the appropriate electrodes. The prior art knows also uniaxially aligned PL LCP, where rubbing substrate has been used [27].

v) Furthermore, in the prior art, luminescent quest molecules or polymers are aligned, when their host matrix is mechanically aligned, which leads to polarized emission with suitable materials. In polarizing excitonic energy transfer (EET), luminescent quest molecules, or polymers, are located in an aligned host matrix containing s.c. sensitizers. Unpolarized light is absorbed by randomly distributed and randomly oriented sensitizer molecules resulting in excitation, which is passed on to the aligned quests and recombined, leading to polarized emission. If both guests and hosts belong to the LMW LC:s, this structure can be sandwiched and switched by electric field between in-plane and out-of-plane alignments. In the polymer field, the photo luminescent (PL) EET system is developed by Paul Smith's group containing a uniaxially aligned ultra high molecular weight polyethylene (UHMW PE) host, a substituted -phenylene-ethylene guest as a luminescent polymer, and selected sensitizers (coumarines) [28]. This concept combines low degree of polarization in the absorption and high degree of polarization in the emission [29]. Therefore, the composite material can utilize a larger part of the excitation light than the aligned molecules alone, still showing a high degree of polarization in emission. This leads to high PL efficiency. It is also claimed that poly(2,5- pyridinediyl) can be used in such system.

vi) Also in the art, circularly polarized (CP) light can be produced using specific assembled molecules, such as selected substituted polythiophenes. Circularly polarized light can in turn be transferred into linearly polarized light or, on the other hand, circularly polarized light can be used as such in displays containing chiroselective molecules or polymers. In these cases, conjugated polymers, especially polyalkylthiophenes, are modified using chiral side groups. Polymers for CP light are developed e.g. by Rene A. J. Janssen's and E. W. Meijer's groups [30].

Summary of the Invention

It is an object of the present invention to eliminate the above-mentioned problems of the prior art and, primarily, to provide novel materials which comprises orientated chains of rod-like polymers. It is a second object of the invention to provide a method of producing oriented rigid-rod-type polymer materials.

The present invention is based on the finding that it is possible to provide fluid-like smectic liquid crystals based on rigid rod polymers by physically complexing side-chains to the rods. The polymers capable of forming these smectic liquid crystals are, in particular, conjugated polymer rods comprising repeating units consisting of aromatic, cyclic or heterocyclic rings linked, optionally via an alkylene group, optionally interrupted by a hetero atom. As mentioned above, side-chains are generally used at the processing stage to improve processibility, but covalently bonded side chains are not needed in the final product, where their presence would make it difficult to obtain the desired polymeric structures of the end products.

According to the present invention, physically complexed side-chains are attached to the main-chains by hydrogen bonding at protonated hydrogen bonding sites. Such sites can be formed at hetero atoms in the cyclic units or hetero atoms in the alkylene chains between cyclic units. The protonation is effected by using a sufficiently strong acid, in particular an acid having a pKa value of <0. Typical examples of protonating acids are organic acids, such as sulphonic acids. The oxygen atoms of such an anion are strongly electronegative, which means that they form strong acceptors for the hydrogen bonding when a complex is formed at a hetero atom, usually a nitrogen atom, of the main-chain polymer backbone. The other part of the hydrogen bond is formed by a hydroxyl group. Preferably the hydroxyl group is present on an aromatic group. In particular, the hydroxy compound used is amphiphilic, which means that it contains, in addition to the polar hydroxyl group, another group, which is essentially non-polar, such as a hydrocarbon group formed by an alkyl chain, suitable halogenated chain, such as semiflurorinated chains or the like. The hydroxy compound is, e.g., a phenolic compound containing at least one hydroxylic group and at least one hydrocarbyl residue as ring substituents. The phenolic compound - the hydrogen bonding donor - should be capable of forming a sufficiently strong hydrogen bond that the resulting modified polymer is dissolved in the phenolic compound forms a homogeneous solution.

Thus, as a result, the material obtained is fluid without external solvent. This feature can be utilized by orientating the main-chain rigid rods, e.g., mechanically by gentle shearing or the like. The monomeric groups forming the side-chains can be removed by heating. Thus, they have a sufficiently low boiling point, usually in the range of 20 to 120 °C at 10^"3 Pa that allows for a removal of at least 50 %, preferably at least 70 %, in particular at least 90 % of the side- chains of the side-groups by heating of the material.

Summarizing, first, comb-shaped supramolecules are constructed by complexing a rigid rod polymer with a protonating acid and by attaching side-chain-forming compounds using hydrogen bonds. In the case of using, e.g., hexylresorcinol as a side-chain-forming compound, the two resorcinolic hydroxyl groups of hexylresorcinol perform matching hydrogen bonds to the polymer chain and the hexyl groups form the "combs". Such polymeric comb-shaped supramolecules self-organize to form nanoscale structures, as evidenced by X- ray diffraction data discussed below. The supramolecules obtained are fluid-like liquid crystals. Their fluid properties facilitates orientation of the rods e.g. by flow. After alignment (orientation), the side chains of the aligned supramolecules are cleaved by evaporating the hexylresorcinol combs in vacuum oven. This gives solid films with very high overall orientation. When the starting material is, e.g., a luminant polypyridine polymer, the resulting materials exhibits polarized luminance with very high efficiency. Such polymers can be used in display technology.

It was found that the supramolecules enables "nanomanufacturing" based on bond reversibility of supramolecules so that the resulting material reveals several crucial enhancements compared with the constituents, such as high, enhanced photoluminescence quantum yield.

Specific advantages of this invention over the prior art include, but are by no means limited to, the following: i) Comb-shaped supramolecules of conjugated, rigid rod-like polymers, ii) Self-assembly of the supramolecules. iii) Hierarchical structures of supramolecular conjugated polymers, iv) Rich phase behaviour of the self-assembled supramolecules. v) Liquid crystalline phase behaviour of the self-assembled supramolecules. vi) General methodology vii) Exceptionally high efficient polymer concentration in supramolecular structure viii) Excellent chemical, mechanical and thermal stability ix) No acidic solvents needed. x) Good opto-electronic properties, such as photoluminescence. xi) Anisotropic opto-electronic properties, such as absorption dichroism and polarized luminescence. xii) Enhanced opto-electronic properties due to cleavage, such as efficient emission and high quantum yield, xiii) By removing bulky side groups, close interchain packing can be achieved with highly oriented chains preventing cross over points which would be potential sites of aggregation or excimer formation. xiv) Less defects in resulting material compared with its constituents.

All these are important properties in many molecular electronics applications.

Additional objects, advantages and novel features of the invention will be set forth in the part in the description which follows, and in part will become apparent to those skilled in the art on examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of instrumentalities and combinations particularly pointed out in the appended claims.

Brief Description of the Drawings

This invention is described with reference being made to the drawings in which

Fig. 1 presents the X-ray diffractions patterns of PPY(CSA)o_.5(PRES)₀.₅ and PPY(CSA)o.₅(HRES)o.₅. Adapted from [31]. Abbreviations are presented in text.

Fig. 2 presents the small-angle X-ray scattering pattern of PPY(CSA)₀.₇ (HRES)ι_.5 as a function of temperature during slow cooling (5 °C/min) (A) and the corresponding full width half maximum (fwhm) of 100, in the first heating (circles) cooling (squares) cycle (5 °C/min). At the first stage material becomes gradually fluid-like and the peak sharpenes, whilst intensity remains high. Between 120-140 °C the scattering intensity drastically decreases and fwhm increases correspondingly. Simultaneously initially birefringent material becomes optically isotropic. This corresponds to the order-disorder transition (ODT) which is reversible during cooling. Nevertheless, the order remains good, when cooling back to the room temperature.

Fig. 3 is the small-angle X-ray scattering pattern of PPY(MSA)ι_.0(OG)₀.₇₅ at 130 °C. Adapted from [32]. This is one example of the phases. Coexistence of the self-assembled cylindrical liquid phase and lyotropic liquid phase being supramolecular analogy for polymer-dispersed liquid crystals (PDLC). Fig. 4 presents the X-ray diffraction patterns of aligned films (- 10 μm) showing the self- organized supramolecular structure, molecular structure within the surpramolecular structure and their high overall alignment.. Scattering intensity curves in directions normal i.e. equatorial out-of-plane (perpendicular to polymer chain, normal to the surface, solid line), equatorial i.e. equatorial in-plane (perpendicular both to polymer axis and surface normal, dashed line) and meridional (parallel to the polymer chain axis, dotted line) for PPY(CSA)o_.5(OG)o._5. Adapted from [31].

Fig. 5 is the intensity curve corresponding of PPY(CSA)₀.₅(HRES)o_.5 (A) and the corresponding normalized one-dimensional correlation function calculated normal to the lamellae according to equation (1) (B). Adapted from [31].

Fig. 6 presents absorption dichroism (dashed lines) and polarized emission (solid lines) of aligned films of PPY(CSA)o_.5(HRES)_0.5. The absorbance curve in the right part of the figure was measured with polarized light. The strongest absorbance was obtained when the c axis was placed parallel to the polarization vector of the probe light, while the weaker absorbance curve was obtained for their mutual perpendicular orientation. The luminescence spectra were obtained with the c axis in vertical orientation for both curves. High luminescence is observed when both the excitation light (λ=370 nm) and the detected emission are vertically polarized, parallel to the c axis. The weaker luminescence is obtained when the excitation and detected emission are both horizontally polarized. Adapted from [31].

Fig. 7 is a schematic presenting a self-assembly of supramolecules and subsequent cleavage of the side groups as a tool to construct material with less defects and high overall order to allow improved electronic properties. (A) Self-assembly of the comb-shape supramolecules of rodlike polymers leads to high local order. White layers denote supramolecular side chains. (B) The fluid state allows facile overall alignment and polarized emission. (C) Cleavage of the side groups of the supramolecules results in solid films with enhanced photoluminescence. This can be accomplished in a vacuum oven. Adapted from [31].

Table 1 presents examples of characteristic FTIR peaks of complex and its constituents. Detailed Description of the Invention

As discussed above, the present invention deals with the alignment of orientation of conducting and luminating polymer. By orientating conjugated polymers their properties can be considerably improved for example by increasing the level of conductivity in the direction of the chains, and completely novel properties can be imparted on the non-orientated material, such as polarized luminescence. Conjugated polymers are rod-like and therefore crystalline and it is not possible to orientate them as pure material.

Generally, the present invention therefore provides complex comb-shaped supramolecules based on conjugated rod-like polymers. These supramolecules comprise: i) π-conjugated polymer or oligomer backbone; ii) an acidic dopant complexed with the polymer moieties; and iii) amphiphilic side-chains hydrogen-bonded to the complex formed by the polymer and the dopant.

The present invention provides self-assembly of the supramolecules due to bonding and due to the microphase separation of the polar and non-polar parts of the supramolecules. These self-assembled structures reveal exceptionally good nanoscale order and coherence. This comprises: i) Supramolecular order ii) Molecular order within the supramolecules iii) π-stacking of the polymers within the supramolecules.

The self-organized structures comprise several hierarchy levels without covalently bonded block-co-polymer structure. The present concept allows for phase tailoring of supramolecules over the largest possible range - from crystals to disordered liquid - which is uncommon, as no liquid crystalline (LC) state was achieved using other solvents.

These structures reveal rich phase behaviour in films and, in particular, films thereof are fluids even without an additional solvent, which is uncommon, and show thermotropic liquid crystallinity.

The present invention utilizes the processing and macroscopic alignment advantages associated with the liquid crystalline phase behaviour of the supramolecules. According to a preferred embodiment of the invention, self-assembled supramolecules are formed in high quality spin-coated thin films, wherein the lamellae, in the case where the primary self-assembled structure is lamellar, are aligned normal to the substrate.

The complexes exhibit good opto-electronic properties, such as photoluminescence, electron transport or conductivity.

The method according to the present invention provides for macroscopic alignment of the self- assembled supramolecules based on the liquid crystalline nature of the material. This process comprises the simultaneous phenomena of: i) Alignment of the self-assembled supramolecular structure, ii) Alignment of the molecular structure within the self-assembled supramolecular structure iii) Alignment of the higher hierarchies beyond the primary self-assembled supramolecular structure.

In a preferred embodiment of the present invention, the high self-assembled order and the macroscopic overall order due to alignment crucially determines the opto-electronic properties of the material.

The aligned polymers within the structure result in the anisotropic opto-electronic properties, such as absorption dichroism and/or polarized luminance, of the material.

According to a further preferred embodiment, the method according to the present invention is employed for producing films of aligned conjugated rod-like polymers with enhanced optoelectronic properties. In this embodiment, the method involves fabrication of highly organized and aligned self-assembled supramolecules and cleavage of their constituents. This process comprises, but is not limited to, the steps of: i) Formation of comb-shaped supramolecules in solution, ii) Evaporation of the solvent, iii) Drying of the complex, iv) Annealing of the complex. v) Alignment of the material onto the smooth substrate. vi) Cleavage of the side groups of the materials using e.g. heating and/or vacuum. In another general aspect this invention provides the supramolecules of rod-like conjugated polymers using hydrogen bonds by any of these processes.

As a first step of the invention supramolecules are formed. For the purpose of the present invention "supramolecules" denote well-defined, discrete oliogomolecular species that result from the intermolecular association of a few molecular components (typically a receptor and its substrate(s)) following a built-in "Aufbau" scheme based on molecular recognition (Jean-Marie Lehn: Supramolecular Chemistry, NCH, Weinheim, 1995, p. 7)

Without loss of generality in this work, comb-shaped supramolecules of conjugated rod-like polymers have been developed based on protonation of polymer moieties by acid "dopant" and hydrogen bonding 'side- chains', which contain the repulsive alkyl chains required for mesomorphism [15]. Preferably these supramolecules comprise:

i) π-conjugated polymer or oligomer backbone. These materials include but are not limited to:

In above formula, each of R] to R is independently hydrogen, a linear or branched alkyl having 1 to 20 carbon atoms, or an aryl group. These groups may be substituted with at least one substituent selected from lower alkyl, halo and hydroxy groups. ii) Acidic dopant complexed with the polymer moieties. These materials include but are not limited to:

O

II O_^S- R

I! O

In above formula, R is a linear or branched alkyl having 1 to 20, in particular 1 to 12 carbon atoms, an alicyclic group preferably containing 5 to 8 carbon atoms, an aryl group or an aryl- alkyl group, said alkyl, alicyclic or aryl group optionally bearing at least one substituent selected from lower alkyl, halo and hydroxy groups.

iii) Amphiphilic side chains hydrogen bonded to the complex of polymer and dopant. These materials include but are not limited to:

In above formula, R^R^R^R-^ can be independently selected from hydrogen and non-polar residues, at least one being a non-polar residue. The non-polar residues are preferably selected from linear and branched alkyls having 1 to 20 carbon atoms, alicyclic, aryl and aryl-alkyl moieties, each of the substituents optionally and independently comprising also ether, carbonyl or ester groups. The hydrogen bonding compound can be an alkyl phenol, comprising one, two or three hydroxyl groups and one or more alkyl groups with a length of at least four carbon units. Thus, based on formula IN above, the hydrogen bonding compound is typically a alkyl dihydroxy benzene or alkylphenol. However, it should be pointed out that, generally, the amphiphilic side-chains, i.e. the hydrogen-bonding compound, may consist of any suitable compound having a polar group, such as at least one hydroxyl group, and at least one non-polar tail comprising at least four carbon, silyl, or halogenated repeat units.

The capability of the hydrogen-bonding compound of dissolving the protonated polymer can be assessed by optical microscopy. Thus, a supramolecule according to the present invention is considered to be dissolved in the hydrogen-bonding compound if a sample thereof does not exhibit any or only minute amounts of insoluble particles. Such samples can generally be characterized as "homogeneous".

In some embodiments camphorsulfonic acid (CSA) is used in complexes. CSA-complexation leads to efficient photoluminescence (PL) as the pyridyl lone electron pairs are orthogonal and unconjugated with the ring π cloud [13].

In most embodiments, these supramolecules self-assemble to the exceptionally well-organized structures. For example, the register between self-assembled layers of present concept is not only far better than that of self-organized semifiexible polymers, such as polyalkylhtiohenes, like poly(3-hexylthioρhene) (P3HT) [33] or poly(3-dodecylthiophene) (P3DT)[34], but also that of gold-crystallized rigid monodisperse oligomeric poly(oxy-l,4-phenyleneoxy-l,4- phenylenecarbonyl-l,4-phenylene) (PEEK) [35].

The side groups can also be regarded as hydrogen bonding solvents allowing exceptionally high solubility, due to the matching hydrogen bonds.

These supramolecules allow phase-rich phase behaviour. These phases include but are not limited to: i) Crystalline phase ii) Co-crystalline phase iii) Self-assembled i.e. mesomorphic solid phase. iv) Self-assembled solid phase with several hierarchy levels. v) Self-assembled liquid, i.e. liquid crystalline (LC) phase. vi) Self-assembled liquid phase with several hierarchy levels. vii) Coexistence of two self-assembled phases. viii) Coexistence of self-assembled and lyotropic liquid crystalline phase. ix) Disordered, isotropic phase.

Most embodiments exhibit the LC state, which is the requirement for the alignment.

In all embodiments, the highly organized self-assembled structure is related to the highly ordered molecular structure within the self-assembled supramolecular structure, and they along with the macroscopic alignment of the molecular structure, which is inherently related to the alignment of the supramolecular structure, are requirements for the anisotropic optoelectronic properties.

According to the present invention, the side groups are selected that can be removed i.e. cleaved, i.e. they allow disassembly of the supramolecules using methods like heating and/or vacuum. When this is performed after alignment in the mesomorphic LC state, the resultant solid material retains high electronic anisotropy and enhanced opto-electronic properties, such as high photoluminescence quantum yield (PLQY). In this way, supramolecules are used as intermediates for aligned conjugated microstructures.

As a result, a highly oriented solid polymer film, comprising a conjugated rigid nitrogen- containing polymer and a protonating compound, is produced.

The film comprises, as pointed out above, preferably at least one conjugated nitrogen- containing polymer, at least one protonating compound, and at least one hydrogen bonding compound, wherein the admixtures form a self-organized periodic structures with periodicity of 10 to 200 A, where at least 50 %, preferably at least 70 %, in particular at least 90 %, of the initial of the weight the hydrogen bonding compound can be removed.

A film prepared from such an intermediate product exhibits periodic structures with a periodicity between 3-200 A, which have been aligned so that using a X-ray scattering analysis using a 2-dimensional detector, at least 90 %, of the total integrated intensity of X-ray reflection arising from this periodicity is within the angular cone of < 45 °, preferably < 25 °, in particular < 15 °.

Summarizing the main steps of the process, it can be noted that first hydrogen bonding sites are formed on rigid rod polymer chains by complexing the polymers with a protonating agent. Preferably a protonating agent having a pKa of less than 0, in particular less than -1, is used. Such hydrogen-bonding-sites are formed preferably on each repeating unit of the polymer. There can be, however, depending on the chemical composition of the repeating units, e.g. the number of heteroatoms per repeating units, generally 0.1 to 5 hydrogen-bonding-sites per such unit. In the following step, comb-shaped supramolecules are constructed using hydrogen bonds, whereby a compound having a polar group capable of forming hydrogen bonds with the protonated complex on the polymer is contacted with the protonated polymer. The compounds have also has at least one non-polar group, e.g. comprising at least four carbon, silyl, or halogenated repeat units. As a typical example of a useful compound, hexylresorcinol can be mentioned. This kind of a compound is attached along the chains of the rigid rod polymer at the hydrogen-bonding-sites. In the case of hexylresorcinol, the two resorcinolic hydroxyl groups of hexylresorcinol perform matching hydrogen bonds to the polymer chain and the hexyl groups form the "combs".

Such polymeric comb-shaped supramolecules self-organize to form nanoscale structures, as evidenced by X-ray diffraction data. The supramolecules have spectacular properties in the sense that they are fluid-like liquid crystals. Their fluid properties allow easy orientation of the rods e.g. by flow. After the alignment we disassemble the aligned supramolecules by evaporating the side-chains, such as hexylresorcinol combs, in vacuum oven. This gives rise to solid films with very high overall orientation. The resulting materials show polarized luminance with very high efficiency, and find application in display technology.

As an alternative to flow-induced or shear-induced orientation (alignment), orientation can be based on application of an external field, such as electrical or a magnetic field over the supramolecule composition.

It should be pointed out that in the present invention, self-assembly is performed using comb- shaped supramolecules instead of comb-shaped molecules, as e.g. in the case of poly(alkylthiophenes). Further, in the case of poly(alkythiophenes) the combs cannot be removed at the end due their covalent bonding.

The present invention also provides a novel scheme to use supramolecules, not only to achieve functional material by assembling supramolecules but also by the consecutive cleaving of the side chains. This concept is by no means limited to luminant materials, it can be used to construct generic materials with less defects.

As has been discussed above, the technical solution of the invention comprises, according to a particularly preferred embodiment, forming of a self-organized liquid crystalline phase by attaching by physical bonds side groups to the rod-like polymer; orientating the material based on liquid-crystallinity in a flow field; and removing the light side groups by heating the material, preferably in vacuum, to leave a heavy polymer, which now is purified and both crystalline and orientated and exhibits completely new properties, such as polarized luminescence. For additional clarity, a particular embodiment is illustrated in attached Figures 7A to 7C, which are also referred to in the examples.

Figure 7A shows the first stage, viz. construction of polymeric supramolecules by hydrogen bonding eg. hexylresorcinol to polypyridine camphor sulphonate. Such comb-shaped supramolecules self-organize to form lamellar nanostructures with peridiodicity of ca 20 A. Within the layers the polypyridine rods are not yet aligned. The white layers denote the hexylresorcinol.

Figure 7B shows the second stage: The lamellar self-organized structure can also be regarded as a thermotropic liquid crystal. It is fluid-like without additional solvent (which is uncommon). The rods can be easily aligned even by a gentle sweep between two microscope slides.

The third stage is shown in Figure 7C: As the hexylresorcinol is oligomeric and only hydrogen bonded to the polymer chains, they can be removed in vacuum oven under gentle heating.

The properties of the present films were already discussed above. However, film according to the present invention, based on polypyridine, may exhibit polarized emission where at least 90 % of the total luminance is emitted in the angular cone < 65°.

As mentioned in the introduction, the polymer chains are "aligned". This will appear from the fact that they are generally oriented in the same direction. Typically, the alignment will manifest itself in the case of luminant polymers by the feature that the films exhibit polarized emission where luminance parallel to the polymer chains and perpendicular to them differs by a multiplicative factor of at least 2, preferably of at least 4.

EXAMPLES

This invention will be further described by the following examples. These are intended to illustrate the invention but not to limit its scope. EXAMPLE 1

This example concerns the preparation of comb-shaped supramolecules of rod-like π- conjugated polymers.

Polymer Synthesis

Poly(2,5-pyridinediyl) (PPY) was synthesized by dehalogenation poly-condensation of 2,5- dibromopyridine with tetrakis(triphenylphosphine)-nickel(0) prepared in situ from reduction of NiCl₂ by Zn in the presence of PPh₃ in N,N-dimethylformamide. The molecular weight was „=6000 g/mol determined using GPC and light scattering and PPY consisted of random mixture of head-to-head and head-to-tail units [36]. The polymer could equally well be regioregular head-to-tail type.

Supramolecules

A stoichiometric complex of PPY and methanesulfonic acid, PPY(MSA)ι_.0 was prepared dissolving equal number of moles of MSA and repeat units of PPY in formic acid as a 1 wt-% solution at room temperature or under moderate heating. Because MSA is hygroscopic, it was stored under nitrogen. After mixing, the solvent was evaporated at room temperature. The complexes were dried in vac at 60 °C for 2 days. The complexes with camphorsulfonic acid (CSA), i.e. PPY(CSA)_X, were prepared similarly. CSA was dried before use.

The side-chains were formed by hydrogen bonding of phenolic amphiphiles, such as 5-pentyl- ,5-dihydroxybenzene (PRES), -hexyl-/,5-dihydroxybenzene (HRES), octyl phenol (OP) or octyl gallate, i.e. i-octyl-3,4,5-trihydroxybenzoate (OG). Further complexes with amphiphiles were prepared similarly in dilute solutions of formic acid, followed by rapid evaporation and vacuum drying. The resulting complexes are denoted PPY(acid)_x(amphiphile)_y, e.g. PPY(CSA)o.₅(PRES)o.₅. To ensure the formation of homogeneous complexes the samples were annealed either at their liquid state or at their isotropic disordered state (e.g. at 190 °C for PPY(MSA)i_.o(OG)₂₀) for 10 minutes [15]. Solid samples were not annealed. Materials were stored in desiccator but not at inert conditions. All experiments here and hencefort were made in air as well. The colours of the materials varied from yellow (pure PPY and PPY(acid)) to orange or red (further complexes). It should be noted that PPY, MSA or CSA and all mentioned amphiphiles were soluble in formic acid both separately and as combinations. Formic acid does not protonate PPY [11] and it does not essentially react with OG or OP during the process. Rapid evaporation and low temperatures resulted in clear solutions with resorcinols but harder conditions or use of the stronger acid (such as dichloroacetic acid) lead to red colour related with their chemical reactivity. Formic acid can be evaporated perfectly under the mentioned conditions. No peaks of the residual formic acid were observed in the FTIR spectra

The complex formation has been studied using optical microscopy and FTIR. Nicon optical microscope was used. FTIR measurements were carried out using Nicolet Magna-IR 750 Spectrometer. Either liquid or solid state sample and transmission method using KBr (Fluka) windows of 150 mg were applied. Liquid samples of 0.1 ml were detected between two windows. Solid state samples were made using standard method (1 sample of 1 mg was mixed and ground finely with KBr and the sample was pressed using force of 100 kN and duration of one minute) with one window. All samples were dry and stored in desiccator.

Examples discussed below were uniform at the optical resolution, unless otherwise stated. The changes of the characteristic FTIR peaks for PPY(acid)_x compared with the superposition of those of PPY and acid, was used to conclude that the protonation takes place, which was also known in art [13]. Same argument was used to claim that the hydrogen bonding appears between PPY(acid)_x and amphiphiles.

Three kinds of samples were studied: The bulk samples (thickness of ca. 1 mm), the cast films (ca. 10 μm) and the spin-coated films (below 100 nm).

EXAMPLE 2

This example involves the self-organization, i.e. self-assembly of supramolecules in Example 1 in bulk samples (thickness of ca. 1 mm).

Optical Microscopy with Crossed Polarizers

Samples were studied using optical microscope described in Example 1 with crossed polarizers. All samples were found to be birefringent under crossed polarizers suggesting locally anisotropic, mesomorphic or liquid crystalline structure, unless informed to the contrary. X-Ray Diffraction

The mesomorphic structure formation of supramolecules, which is crucial, was extensively studied using X-ray diffraction by means of small-angle X-ray scattering (SAXS) and wide- angle X-ray scattering (WAXS).

Small angle X-ray scattering experiments (SAXS) were partially carried out using synchrotron radiation with the perpendicular transmission method at the Dutch-Belgian beamline at ESRF[37]. The sagittally focusing double crystal monochromator (Si(l 11)), the meridionally focusing coated mirror and the energy of 10 or 16 keN (λ=0.124 or 0.078 nm) were used. The bending radius of the crystal mirror was adjusted to focus the beam at the two-dimensional wire chamber detector. The distance between the sample and the detector was 1.28 or 1.7 m.

X-ray scattering experiments were partially carried out using CuK_α (λ=1.54 A) radiation from sealed X-ray tube and the perpendicular transmission method. The beam was monochromatized with aΝi-filter and a totally reflecting glass block (Huber small-angle chamber 701). The transverse dimensions of the beam were reduced with slits to approximately 0.1x0.5 mm² at the detector. The intensity was measured using an image plate (IP) system from Molecular Dynamics. Sample to screen distance was 90 mm and pixel-size 88x88 μm². Thickness of the samples was ca. 1 mm.

WAXS experiments were partially made with transmission mode by using CuK_D radiation, monochromatized with a quartz monochromator in the incident beam. A scintillation counter was used as a detector.

X-ray diffraction curves of all discussed samples showed several very sharp reflections at low scattering angles at room temperature following the sequence q*, 2q*, 3q*..., which clearly indicated a lamellar mesomorphic self-organized supramolecular structure.

The interlayer distance d ≡ 2π I q * was dependent on the side chain length, as expected, but does not followed the simple scheme of side-chain tilt and interdigitation.

At higher scattering angles there was a broad amorphous halo (q') at ca. 1-1.5 A^"1 arising from inter- and intrachain short-range order. A sharp reflection q " was superimposed on the amorphous halo near 1.8 A^"1 and, depending on the composition, an additional reflection was also observed at 3.0-3.2 A^"1. The position of q" was independent of the side chain length but it disappeared on increasing the side chain concentration (xy) and/or the temperature. This clearly indicated the good molecular structure and control within the self-organized supramolecular structure.

Detailed structure and appropriate picture of the nature of the structure in the samples in Example were presented elsewhere [31].

EXAMPLE 3

This example involves the generality of supramolecule formation and self-organization in Example 1 and in Example 2.

Supramolecules with Flexible and Semi-Rigid or Rigid Ladder-Like, i.e. Fused Ring, Conjugated Polymers

To show that the current methods are not limited to the rigid rod-like polymers the concepts were generalized to the semi-rigid conjugated polymers, to the flexible polymers and to the rigid conjugated ladder-like polymers using simple model compounds.

Semi-rigid (kinked) poly(2,6-pyridinediyl) (PmPy) was prepared in a similar manner than PPY from 2,6-dibromopyridine[36]. Flexible poly(4-vinylpyridine) was supplied by Polymer Source. Ladder-like pyrolyzed polyacrylonitrile, i.e. polypyridinopyridine was prepared by heating polyacrylonitrile at 300 °C in vac (10^"s mbar) for three hours. FTIR spectra revealed that the pyrolysis was successful [38].

Optical Microscopy with Crossed Polarizers

With careful phase screening the uniform phase regions were found. As expected, the birefringence was not so high as in the case of rigid rod-like polymer.

X-Ray Diffraction

X-ray diffraction peak q* was typically seen at low angles indicating self-organization as described in Example 2. The quality of structure was not so high as in the case of rigid rod- like polymer. The peak q ' ' was not occur for the corresponding complexes with metα-coupled (kinked) poly(2,6-pyridinediyl) or flexible poly(4-vinylpyridine) which do not form well- defined structures in the main chain direction due to coiling.

EXAMPLE 4

This example involves the phase behaviour of the self-organized structures in Example 2 and in Example 3.

Optical Microscopy and Differential Scanning Calorimetry

The phase behaviour was studied using optical microscopy as a function of temperature. DSC measurements were performed using Mettler Toledo DSC 821^e system. Typical sample size was ca 1 mg.

The starting materials are crystalline. PPY complexed by CSA, i.e. PPY(CSA)_Xj is an infusible solid. In the following examples, CSA has been used and only part of the pyridines have been protonated, i.e. x<\, as this maintains strong PL [13]. For small x and , e.g. x=0.25,y=0.25 or 0.5, a glassy birefringent material between 25-200 °C is obtained. For increased values, x=y=0.5, a glassy material was observed at 25 °C but at moderate temperatures, a birefringent fluid was formed with a broad endothermic DSC rise, typical for noncrystalline materials. Further increase of x and y resulted in a LC state even at 25 °C and a transition to an isotropic (non-birefringent) disordered fluid at a higher temperature. If ylx > 2, a biphasic system, i.e. either material containing two different LC phases or phase separated material, was typically seen. Qualitatively the same behaviour is observed for all the above amphiphiles.

In the following examples, the amount of amphiphile was kept small for two reasons. First, interesting electronic properties occur primarily in the high concentration region of the polymer. Secondly, if the amount of amphiphile is too high, the proportional number of hydrogen bond acceptors was reduced and system was phase separated.

In the intermediate concentration region, typically x=\ y=2, the complexes revealed the following behaviour. At high temperatures, the mixture was homogeneous fluid at the resolution of optical microscope. Under crossed polarizers it showed no birefringence indicating optically isotropic structure: At moderate temperatures birefringent fluid was observed using crossed polarizers, suggesting optically anisotropic structure. At room temperature the material was birefringent solid under crossed polarizers, suggesting crystallinity. Accurate composition limits and temperatures were dependent on the material. For selected compositions, e.g. for PPY(CSA)ι_.o(PRES)_2.o, the complexes were fluid-like also at room temperature.

X-Ray Diffraction

Phase behaviour was extensively studied using X-ray diffraction as a function of temperature. At the higher side group concentrations the behaviour of reflections were qualitatively as follows: In the isotropic disordered liquid state SAXS intensity patterns showed a broad intensity maximum. Such peak was not due to order but it was assigned to a correlation hole peak. Material revealed disorder-order transition during cooling seen as a birefringence. SAXS intensity patterns showed at the same temperature a pronounced change where the SAXS peak (q*) becomes stepwise narrower and the peak height increases clearly indicating a nanoscale structure formation. At still lower temperatures WAXS peak (q ') appeared indicating molecular order within the self-organized structure.

At the lower side group concentrations (e.g. x=y=0.5) rod-like polymers had no space to be disordered and both the SAXS peak (q*) and the WAXS peak (q ') were present at all temperatures also in the fluid like state, which indicated both supramolecular and molecular order within supramolecules in LC state, respectively.

At still lower side group concentration solid phase with all above described scattering features was observed at all temperatures.

Ion Transport

Conductivity was measured using a Keithley 2400 and a 4-probe constant current method. The sample geometry was a thin film on a glass plate with 4 gold electrodes evaporated onto it. The width of the electrodes and their spacing were 0,05...1 mm. The sample was sealed using glass cover slip glued using epoxy. The temperature sweeps were provided by Linkam hot stage. The temperatures were determined based on thermocouple attached to the stage. The sample temperature differs slightly from it and the measurement was calibrated for each sample size and geometry and thickness of glass.

Complexes revealed thermally activated current flow. The results showed also that whenever a self-organized nanostructures were formed i) the voltages seemed to reach an astonishingly stable values during the 30 min measurement period; ii) the voltage reverted its polarity promptly upon polarity reversal; and iii) the voltages followed linear relationship as a function of current

EXAMPLE 5

This example involves further examples of the phase behaviour of the self-organized structures in Example 2 and in Example 3.

Optical Microscopy, Differential Scanning Calorimetry, and X-Ray Diffraction

The selection and balance of the supramolecular side chains was not straightforward because of limited mixing entropy and crystallization tendency of PPY. Macrophase separation occured in two distinct case, (i) The connection between polymer and side chains compared with the repulsion of the alkyl tail is not strong enough and the system is phase separated for entropy reasons. The relatively small strength of the hydrogen bond has to compensate the repulsion and only narrow selection of phenolics, e.g. HRES, and OG showed a desirable balance to nominally stoichiometric PPY complex with MSA, PPY(MSA)ι.o: A gallate with a longer and more repulsive tail, l-lauryl-3,4,5-trihydroxybentzoate has phase separation tendency, (ii) Concentration of an amphiphile was too high or too low. In the former case there are no connection sites available and in the latter case crystallinization tendency of backbone may be higher than that of mixing. In the case of OG, five regions were seen. PPY(MSA)ι_.0 with (a.) three mole of OG: OG had phase separation tendency to organized domain and pure OG. (b) Two moles of OG formed one uniform lamellar phase and isotropic phase at higher temperature[39]. (c) One mole of OG showed coexistence region of two lamellar phases, (d) 0J5-0.5 moles of OG revealed coexistence region of one crystalline or potentially liquid crystalline phase and self-organized cylindrical (Vϊ, V2,V4,V5,...) reflections at higher temperature, which indicated the natural approach of lyotropic phase with increasing PPY concentration. If OG content was very small, (e.) crystalline phase was approached [32]. With HRES the transition limits are lower than in the case of OG.

When increasing PPY(MSA)ι_.o concentration in OG a proposed lyotropic liquid crystalline phase and a cylindrical potentionally mesomorphic phase are observed simultaneously (case d.). This realizes the supramolecular analogy to the polymer-dispersed liquid crystals (PDLC) [40]. EXAMPLE 6

This example involves the self-organization in spin-coated films of materials in Example 2 as well as the alignment of the self-organized structure.

Preparation of Thin Films

The films were spin-coated onto quartz substrates at typically 2000 rpm for 30 s from 1-3 wt- % filtered solutions of formic acid. The size of the sample was ca. lxl cm².

Macroscopic Quality

Uniformity of the films was studied using scanning near-field optical microscopy (SNOM). The surface quality and the thickness of the films have been studied using Atomic force microscope (AFM) and SNOM. AFM experiments were performed using aNanoscope III A instrument (Digital Instruments) operating in the noncontact mode. Scanning near-field optical microscopy experiments were carried out using a modified commercial device from Topometrix (Aurora) in transmission geometry. The sample was excited with ca. 500 μW of 457 nm light from a CW argon ion laser and the luminescence light was collected with an uncoated SNOM probe resulting in a spatial resolution of ca. 100 nm [41].

The near-field images show uniform emission from the sample with smooth surface topography. Evidence of phase separation was not observed. The thicknesses were between 50 and 150 nm and the roughness of the surface ca. 3-15 nm as obtained from a 1 μm² sample area using AFM.

X-Ray Diffraction and Macroscopic Alignment of the Self-Organized Structure

The self-organization was investigated using grazing-incidence small-angle (and wide-angle) scattering (GISAXS /GID). Grazing-incidence X-ray scattering measurements were performed with the sealed X-ray tube and monochromatization setup described in Example 2. The sample was mounted on a Huber goniometer and a translation table. The angle of incidence was ca. 0.2° [41].

In spin-coated thin films the structure is qualitatively similar. The layers align parallel to the quartz surface and grazing-incidence X-ray diffraction patterns reveal a pronounced maximum (q*) perpendicular to the surface (out-of-plane) but not parallel to it (in-plane), as well as broad arc at 1-2 A^"1. Note, in particular, that no self-organization promotor was needed here.

Photoluminescence

Photoluminescence (PL) spectra were measured using a charge coupled device (CCD) spectrograph following excitation at the peak of absorption by monochromated light from a HgXe lamp. All samples were found to emit green light revealing one broad maximum (at 510-550 nm depending on the composition) when excited with the UN light. Excitation profiles were determined and contained one broad maximum at 350-400 nm depending on the composition. This qualitatively corresponded to the photoabsorption spectra. Electron Transport and Electroluminescence

EXAMPLE 7

This example involves the macroscopic alignment of self-organized structures and in Example 2 in the fluid-like phase in Example 4 in cast films.

Alignment of Self-Assembled Supramolecular Structure and Molecular Structure within the Supramolecular Structure

The LC state in Example 4 allows simultaneous alignment of self-organised supramolecular structure and molecular structure within the supramolecules without an additional solvent. The solution cast fluid-like films were sheared in the in-plane direction by drawing them lightly along the substrate surface (clean quartz or glass) using smooth steel or glass at moderate temperature. In particular, no rubbed substrates were used. To ensure the good result the temperature was so high that the material was completely fluid-like but not too high so that the material was not destroyed. The appropriate temperature for PPY(CSA)₀.5(PRES)o.₅ was 90 °C, for instance. The rigid polymers were expected to align with their chain axes in the drawing direction and the lamella parallel to the surface. X-ray diffraction patterns were measured ex-situ in three directions with respect to the aligned sample, see typical example in FIG 1.

The reflections from the lamellar structure (q*) were in the equatorial out-of-plane direction and are henceforth denoted as hOO. The reflection q ' ' and its higher order were in the equatorial in-plane and was assigned as 020 and 040. The pyridine rings stack perpendicular to the surface and the corresponding Bragg spacing (3.55 A) describes the stacking distance being nearly the same as in the pure polymer. In bulk samples, the 020 reflection was asymmetric, because it included reflections 120, 220 etc., which were not resolved due to the limited crystallite size, ca. 100 A in this direction. Finally, the reflection at 3.0-3.1 A^'1 was in the meridional direction and may be assigned as 004 since the Bragg distance (ca. 2.1 A) approximately corresponds to one fourth of the length of the suggested PPY(CSA)o.s repeat unit. The reflection at 3.1 A^"1 was then related to the intrachain distance of the pyridine groups in the polymer main chain.

EXAMPLE 8

This example involves supramolecular hierarchy in aligned self-organized supramolecules in Example 2 and in Example 6.

X-Ray Diffraction

Prominent reflections at ca. 0.09 A^"1 were also seen along the meridional direction for the hard solid samples, e.g. CJ ≤O.25. Their appearance was concomitant to broadening of the 100 reflection in samples with low side group concentration. In the fluid-like PPY(CSA)o.₅(OP)ι.o these reflections also appeared but as parallel stripes akin to nematic liquid systems of rod-like molecules. As all these features were observed, a third level of organization i.e. supramolecular hierarchy, unique in conjugated polymers had to be present. When the third, higher level of organization in Example 7 was present, also it could be aligned simultaneously with other levels.

EXAMPLE 9

This example involves the exceptional order of self-organized supramolecular structure in Example 2 and Example 7, which forms the basis of highly ordered rod-like molecules within the supramolecules.

X-Ray Diffraction

One dimensional normalized correlation function (FIG 2.) normal to lamellae had a triangular form and damped out very slowly indicating a highly ordered supramolecular structure. When the instrumental function is taken into account, the coherence length, based on the Scherrer formula for infinite lamellae, L ≡λ/(A2θcosQ) (2Θ = scattering angle), was of the order of 550-800 A along the lamellae for the various compositions. The higher order reflections hOO exhibit nearly linear dependence of the peak widths. Therefore, the reflection widths are predominantly due to lattice parameter fluctuations (microstrains) and the actual crystallite size may be considered far higher.

The structure was permanently improved by annealing, possibly due to release of strain and increase in the size of ordered domains [31].

The normalized correlation function was determined using equation (1).

where / is the measured scattering intensity , q the scattering vector and x the distance.

EXAMPLE 10

This example involves the good order and alignment of the molecular structure within the supramolecular structure and therefore absorption dicroism and polarized photoluminescence. They are of crucial importance.

Optical Spectroscopy

The photonic properties were studied using optical spectroscopy, photo absorption (PA) and photoluminescence (PL). In particular, to investigate molecular order and alignment within the lamellae absorption dichroism and polarized emission were measured. Absorption spectra were measured using a Perkin Elmer Lambda spectrofotometer equipped with Glenthomson polarizers. Photoluminescence spectra were measured using a Jobin Yvon Horiba Fluoromax 3 equipped with Glenthomson polarizers. To correct the difference in sensitivity of the spectrometer a dilute solution of Coumarin 314 in MeOH was used. Accordingly, spectra obtained for vertical polarization of excitation and emission was compared with spectra obtained for horizontal polarization of excitation and emission and this gave the appropriate correction factor (1.26).

The X-ray diffraction results in Example 5 showed that rod-like molecules are aligned within the aligned supramolecules. Optical spectroscopy results were completely consistent with that. See example in FIG. 3 which is the in-plane electronic absorption and PL emission of the aligned supramolecules in cast films. Strong absorption was observed if the c axis is parallel to the polarization of the light. The two absorption spectra have a slightly different shape. The parallel absorption profile has also a slightly redshifted maximum relative to the perpendicular case. This has also been observed in stretch oriented PPY films [17] and is ascribed to a larger delocalisation length in the ordered chains, which lie in the alignment direction. The luminescence spectra depend strongly on the polarization of the excitation and the emission light, leading to 5-fold difference in intensity between the parallel and perpendicular cases. In contrast to the absorption spectra, the two PL spectra have similar shape. This suggests that the origin of luminescence is the same in both cases and is indicative of exciton migration to chain sites of lowest energy. Both absorption and luminescence suggest that the major transition dipoles are oriented parallel to the c axis as is typical for this class of polymers.

EXAMPLE 11

This example involves the opto-electronic efficiency of the self-organized supramolecules in Example 6 and Example 10.

Photoluminescence Quantum Yield

Solid state photoluminescence quantum yield (PLQY) (Φpr) was determined according to the method described by de Mello [43] using a spectrofluorimeter in combination with an integrating sphere [44]. A PTFE coated integrating sphere (Glen Spectra) was mounted into a Jobin Yvon Horiba fluoromax-3. The entry and output ports were in a perpendicular angle configuration (in the spectrometer plane) which meant that the design geometry of the fluorimeter was also used in the integrating sphere measurements. The sample material was coated onto a 10 mm diameter quartz substrate and mounted about 20 mm into the sphere from a holder in the entry port facing the excitation light beam. The measured spectra were background corrected by subtracting the spectrum obtained using a blank substrate and subsequently corrected for the wavelength sensitivity of the fluorimeter and the spectral response of the sphere. The spectral response of the sphere was determined using a calibrated tungsten lamp (Ocean Optics) and the fluorimeter as the detector. The spectral correction factor of the fluorimeter was also obtained using the calibrated tungsten lamp. These two normalisation curves were then used to correct the recorded luminescence spectrum of the sample. This correction is applied to all subsequently measured emission spectra in the measurement of the sample PLQY.

PLQY was calculated using equations (2) and (3).

E_i(λ) - (l - A) - E₀(λ)

Φ« = (2) L_e(λ)- A

where Ej(λ) and Eo(λ) are respectively, the integrated luminescence as a result of direct excitation of the film and secondary excitation. The latter emission is due to reflected excitation light from sphere walls hitting the sample, which in turn is not directly in the path of the excitation beam [1]. A is the film absorbance, which is found by measuring the integrated excitation profiles, i.e. the emission signal measured across the excitation wavelength (± 5 nm), for two situations as follows, Lj(λ) is the integrated excitation when the film is directly excited and Lo(λ) is the integrated excitation when the excitation light first hits the sphere wall as previously explained. L_e(λ) is the integrated excitation profile for an empty sphere.

PLQY of the complexes was comparable with many conjugated polymers, such as poly(alkylthiophene)s (PAT)s [45], but not very high (~1 -10 %), which may indicate twisting of the rings in the mesomorphic state.

EXAMPLE 12

This example involves disassembly of the highly ordered aligned self-assembled supramolecules in Example 5 with the photonic properties described in Example 8 by the removal, i.e. cleaving, of the hydrogen bonded side groups.

Cleaving of the Hydrogen Bonded Side Groups Most importantly, it is shown that the aligned mesomorphic state can be used as intermediate for an aligned solid state.

The hydrogen bonded side chains were cleaved by vacuum treatment (~ 10^"3 mbar) at elevated temperature. Simultaneously, PL was enhanced and the samples remained optically anisotropic as revealed by highly polarized luminescence. After thermal treatment of PPY(CSA)o.₅(HRES)o.₅ at 120 °C for 42 hours, FTIR spectra reminiscent of PPY(CSA)₀.₅ was seen suggesting the cleavage of the HRES (J_m=68 °C), i.e. disassembly of the supramolecule. Correspondingly, PLQY of thin film increased from (10±1)% to (20±1)%, the same as in an optically isotropic PPY(CSA)o.s and PPY. In cast film, the increase from 1 % to (7±1)% was seen. The lighter side chain the easier process. It was also true for the thinness of the film: The thinner film the easier process. Resorcinol (T_m= 110 °C) without alkyl tail can be sublimated very easily and rapidly using slight heating and/or vacuum. With alkylresorcinols best result were got with PRES and OP. With heavier amphiphiles there were some traces present.

Alike result with best FTIR evidence was seen for light PRES (T_m= 48 °C) and thinner films, whereas FTIR spectra of complex with heavy OG (J_m=102 °C) showed signs of residual suggesting the use of harder conditions. Nevertheless, for the cast films of PPY(CSA)o.₅(OG)o_.5 kept in 80 °C for 24 hours, the PLQY increased from ca. 1 % to (7+1) %. Hence, the detailed mechanism of PLQY enhance was delicate and suggested to be the result of the structural improvement and disassembly combined.

Example of characteristic FTIR peaks of complex and its constituents is shown in Table 1. Corresponding table can be made for all amphiphiles.

Therefore, solid films with aligned structures are obtained. The high orientation is demonstrated by X-rays and polarized luminance with high efficiency. TABLE 1

¹ Characteristic peaks of PPY seen in this work and also known in art [46].

² Differs HRES from PRES.

³ Weak trace of HRES.

In summary of the above, the invention includes the following features:

1. In contrast to the hairy rods with covalently bonded side chains, such as PAT:s, the hydrogen bonded side chains can in the present case be removed, cleaved by vacuum treatment (~ 10^"3 mbar) at elevated temperature. Simultaneously, PL is enhanced and the samples remain optical anisotropic as revealed by highly polarized luminescence

2. Supramolecules of rod-like conjugated polymers

3. Self-assembly 4. Phase behaviour, liquid crystallinity i) LC ii) Cylindrical bcc

5. Thin films

6. Macroscopic alignment 7. Hierarchical structures 8. Exceptional order i) Supramolecular order ii) Molecular order iii) π-stacking 9. Absoption dichroism

10. Polarized luminance

11. Cleavage, i.e. disassembly of the supramolecules. i) Solid state ii) Similar absorption dichroism iii) Similar polarized luminance iv) Enhanced photoluminescence quantum yield v) Less defects

References

[I] M. J. Winokur, "Structural Studies of Conducting Polymers," in Handbook of Conducting Polymers, T. A. Skotheim, R. L. Elsenbaumer, and J. R. Reynolds, Eds.

New York: Marcel Dekker, 1998, pp. 707-726. [2] J. H. Schδn, C. Kloc, R. A. Laudise, and B. Batlogg, "Low temperature absorption and luminescence of oligothiophene single crystals," J. Appl. Phys., vol. 85, pp. 2844- 2847, 1999. [3] J. H. Schδn, C. Kloc, and B. Batlogg, "Fractional quantum hall effect in organic molecular semiconductors," Science, vol. 288, pp. 2338-2340, 2000. [4] J. H. Schδn, C. Kloc, A. Dodabalapur, and B. Batlogg, "An organic solid state injection laser," Science, vol. 289, pp. 599-601 , 2000. [5] J. H. Schδn, C. Kloc, and B. Batlogg, "Superconductivity in molecular crystals induced by charge injection," Nature, vol. 406, pp. 701 -704, 2000.

[6] H. Sirringhaus, P. J. Brown, R. H. Friend, M. M. Nielsen, K. Bechgaard, B. M. W. Langeveld-Noss, A. J. H. Spiering, R. A. J. Janssen, E. W. Meijer, P. Herwig, and D. M. de Leeuw, "Two-dimensional charge transport in self-organized, high-mobility conjugated polymers," Nature, vol. 401, pp. 685-688, 1999. [7] J. H. Schδn, A. Dodabalapur, Z. Bao, C. Kloc, O. Schenker, and B. Batlogg, "Gate- induced superconductivity in a solution-processed organic polymer film," Science, vol. 410, pp. 189-192, 2001. [8] R. Maki-Ontto, K. de Moel, W. de Odorico, J. Ruokolainen, M. Stamm, G. ten Brinke, and O. Ikkala, ""Hairy Tubes": Mesoporous Materials Containing Hollow Self- Organized Cylinders with Polymer Brushes at the Walls," Adv. Mater., vol. 13, pp.

117-121, 2001. [9] S. S. Zhu, P. J. Carroll, and T. M. Swager, "Conducting polymetallorotaxanes: A supramolecular approach to transition metal ion sensors," J. Am. Chem. Soc, vol. 118, pp. 8713-8714, 1996. [10] D. A. P. Delnoye, R. P. Sijbesma, J. A. J. M. Vekemans, and E. W. Meijer, "pi- Conjugated oligomers and polymers with a self-assembled ladder-like structure," J. Am. Chem. Soc, vol. 118, pp. 8717-8718, 1996.

[I I] T. Yama oto, T. Maruyama, Z.-H. Zhou, T. Ito, T. Fukuda, Y. Yoneda, F. Begum, T. Ikeda, S. Sasaki, H. Takezoe, A. Fukuda, and K. Kubota, "pi-Conjugated poly(pyridine-2,5-diyl), poly(2,2'-bipyridine-5,5'-diyl), and their alkyl derivatives.

Preparation, linear structure, function as a ligand to form their transition metal complexes, catalytic reactions, n-type electrically conducting properties, optical properties, and alignment on substrates," J Am. Chem. Soc, vol. 116, pp.4832-4845,

1994. [12] J. W. Blatchford, S. W. Jessen, L. B. Lin, J. J. Lih, T. L. Gustafson, A. J. Epstein, D. K. Fu, M. J. Marsella, T. M. Swager, A. G. MacDiarmid, S. Yamaguchi, and H.

Hamaguchi, "Exciton dynamics in poly(p-pyridyl vinylene)," Phys. Rev. Lett., vol. 76, pp. 1513-1516, 1996. [13] A. P. Monkman, M. Halim, I. D. W. Samuel, and L. E. Horsburgh, "Protonation effects on the photophysical properties of poly(2,5-pyridine diyl)," J. Chem. Phys., vol. 109, pp. 10372-10378, 1998.

[14] M. Jonforsen, S. Grigalevicius, M. R. Andersson, and T. Hjertberg, "Counter-Ion

Induced Solubility of Polypyridines," S wtΛ. Met, vol. 102, pp. 1200-1201, 1999. [15] M. Knaapila, J. Ruokolainen, M. Torkkeli, R. Serimaa, L. Horsburgh, A. P. Monkman,

W. Bras, G. ten Brinke, and O. Ikkala, "Self-organized supramolecules of poly(2,5- pyridinediyl)," Synth. Met, vol. 121, pp. 1257-1258, 2001.

[16] T. Yamamoto, "Polarizing polymer film," . JP03089202: Jpn. Kokkai Tokkyo Koho,

1991. [17] F. Feller and A. P. Monkman, "Optical spectroscopy of oriented films of poly(2,5- pyridinediyl)," Phys. Rev. B, vol. 61, pp. 13560-13564, 2000. [18] J. H. Burroughes, D. D. C. Bradley, A. R. Brown, R. N. Marks, K. Mackay, R. H.

Friend, P. L. Burns, and A. B. Holmes, "Light-emitting diodes based on conjugated polymers," Nature, vol. 347, pp. 539-541, 1990. [19] P. Dyreklev, M. Berggren, O. Inganas, M. R. Andersson, O. Wennerstrόm, and T.

Hjertberg, "Polarized Electroluminescence from an Oriented Substituted Polythiophene in a Light Emitting Diode," Adv. Mater., vol. 7, pp. 43-45, 1995.

[20] M. Grell and D. D. C. Bradley, "Polarized luminescence from oriented molecular materials," Adv. Mater., vol. 11, pp. 895-905, 1999. [21] A. J. Heeger and D. Braun, "Visible Light Emitting Diodes Fabricated from Soluble

Semiconducting Polymers," . US5408109: The Regents of the University of California, Oakland, Calif, 1995.

[22] Z. Bao and X. L. Chen, "Process for fabricating polarized organic phonics devices," .

EP1081774: Lucent Technologies Inc, Murray Hill, New Jersey 07974-0636, 2001. [23] J. Hegenbarth and D. R. Carpenter, "Oriented Crystalline Materials," . US5772755: W.

L. Gore & Associates, Inc., Newark, Del., 1998. [24] W. Caseri, T. Sauer, and G. Wegner, "Soluble phthalocyaninato-polysiloxanes: rigid rod polymers of high molecular weight.," Macromol. Chem., Rap. Commun., vol. 9, pp. 651-657, 1988.

[25] M. Grell, W. Knoll, D. Lupo, A. Meisel, T. Miteva, E. Neher, H.-G. Nothofer, U. Scherf, and A. Yasuda, "Blue Polarized Electroluminescence from a Liquid Crystalline

Polyfluorene,"Atv. Mater., vol. 11, pp. 671-675, 1999.

[26] D. Lupo, A. Yasuda, M. Grell, D. Neher, and T. Miteva, "Polyimide layer comprising functional material, device employing the same and method of manufacturing same device," . EP1011154: Sony International (Europe) GmbH 10785 Berlin (DE), Max Planck Institut fur Polymerforschung 55128 Mainz (DE), 2000.

[27] G. Lϋssem, R. Festag, A. Greiner, C. Schmidt, C. Unterlechner, W. Heitz, J. H.

Wendorff, M. Hopmeier, and J. Feldmann, "Polarized Photoluminescence of Liquid Crystalline Polymers with Isolated Arylenevinylene Segments in the Main Chain," Adv. Mater., vol. 7, pp. 923-925, 1995. [28] A. Montali, C. Bastiaansen, P. Smith, and C. Weder, "Polarizing energy transfer in photoluminescent materials for display applications," Nature, vol. 392, pp. 261-264, 1998.

[29] C. Weder, C. Bastiaansen, A. Montali, and P. Smith, "Efficient photoluminescent polarizers, process for forming, and application in display devices," . EP0933655: ETHZ Institut fur Polymere 8092 Zurich, 1999.

[30] E. Peeters, M. P. T. Christiaans, R. A. J. Janssen, H. F. M. Schoo, H. P. J. M. Dekkers, and E. W. Meijer, "Circularly Polarized Electroluminescence from a Polymer Light- Emitting Diode," J. Am. Chem. Soc, vol. 119, pp. 9909-9910, 1997.

[31] M. Knaapila, M. Torkkeli, L. E. Horsburgh, L.-O. Palsson, K. Jokela, I. Dolbnya, W. Bras, R. Serimaa, G. t. Brinke, and O. Ikkala, "Manipulation of Assembled Rod-Like

Supramolecules by Cleaving Their Constituents," submitted, 2001.

[32] M. Knaapila, "Self-Organized Supramolecular Electroactive Polymers," . Espoo: Helsinki University of Technology, 1999.

[33] K. E. Aasmundtveit, E. J. Samuelsen, M. Guldstein, C. Steinsland, O. Flornes, C. Fagermo, T. M. Seeberg, L. A. A. Pettersson, O. Inganas, R. Feidenhands'l, and S.

Ferrer, "Structural anisotropy of poly(alkylthiophene) films," Macromolecules, vol. 33, pp. 3120-3127, 2000.

[34] T. J. Prosa, J. Moulton, A. J. Heeger, and M. J. Winokur, "Diffraction line-shape analysis of poly(3-dodecylthiophene): A study of layer disorder through the liquid crystalline polymer transition," Macromolecules, vol. 32, pp. 4000-4009, 1999. [35] O. Dupont, A. M. Jonas, B. Nysten, R. Legras, P. Adriaensens, and J. Gelan, "PEEK Oligomers as physical model compounds for the polymer. 4. Lamellar microstructure and chain dynamics," Macromolecules, vol. 33, pp. 562-568, 2000.

[36] L. E. Horsburgh, A. P. Monkman, and I. D. W. Samuel, "Synthesis and Characterisation of Polypyridines," Synth. Met, vol. 101, pp. 113-114, 1999.

[37] M. Borsboom, W. Bras, I. Cerjak, D. Detollenaere, D. Glastra van Loon, P.

Goedtkindt, M. Konijnenburg, P. Lassing, Y. K. Levine, B. Munneke, M. Overluizen, R. van Tol, and E. Vlieg, "The Dutch-Belgian beamline at the ESRF," J. Synchrotron Rad., vol. 5, pp. 518-520, 1998. [38] T.-C. Chung, Y. Schlesinger, S. Etemad, A. G. MacDiarmid, and A. J. Heeger,

"Optical Studies of Pyrolyzed Polyacrylonitrile," J. Polym. Scl: Polymer Physics Edition, vol. 22, pp. 1239-1246, 1984.

[39] O. Ikkala, M. Knaapila, J. Ruokolainen, M. Torkkeli, R. Serimaa, K. Jokela, L.

Horsburgh, A. Monkman, and G. ten Brinke, "Self-Organized Liquid Phase and Co- Crystallization of Rod-Like Polymers Hydrogen-Bonded to Amphiphilic Molecules,"

Adv. Mater., vol. 11, pp. 1206-1210, 1999.

[40] D. A. Higgins, "Probing the Mesoscopic Chemical and Physical Properties of Polymer- Dispersed Liquid Crystals," Adv. Mater., vol. 12, pp. 251-264, 2000.

[41] M. Knaapila, M. Torkkeli, T. Makela, L. Horsburgh, K. Lindfors, R. Serimaa, M. Kaivola, A. P. Monkman, G. ten Brinke, and O. Ikkala, "Self-organization of nitrogen- containing polymeric supramolecules in thin films," Mat Res. Soc. Symp. Proc, vol. 660, pp. JJ5.21.1-6, 2001.

[42] S. Dailey, M. Halim, E. Rebourt, L. E. Horsburgh, I. D. W. Samuel, and A. P.

Monkman, "An efficient electron-transporting polymer for light-emitting diodes," J. Phys.: Condens. Matter, vol. 10, pp. 5171-5178, 1998.

[43] J. C. de Mello, H. F. Wittmann, and R. H. Friend, "An Improved Experimental

Determination of External Photoluminescence Quantum Efficiency," Adv. Mater., vol. 9, pp. 230-232, 1997.

[44] L.-O. Palsson and A. P. Monkman, "Measurements of solid state photo luminescence quantum yields of films using a fluorimeter," , vol. in press, 2002.

[45] M. Theander, O. Inganas, W. Mammo, T. Olinga, M. Svensson, and M. R. Andersson, "Photophysics of substituted polythiophenes," J. Phys. Chem. B, vol. 103, pp. 7771- 7780, 1999.

[46] H. Yun, T. K. Kwei, and Y. Okamoto, "Effects of Acidicity and Methylation on the UN and Fluorescence Spectra of Poly(pyridine)s in Aqueous Solutions in the Solid

State," Macromolecules, vol. 30, pp. 4633-4638, 1997.

Claims

Claims:

1. Highly oriented solid polymer film, comprising a conjugated rigid nitrogen-containing polymer and a protonating compound.

2. Film according to claim 1, comprising at least one conjugated nitrogen-containing polymer, at least one protonating compound, and at least one hydrogen bonding alkyl-containing compound consisting of at least one alkyl tail having a length of at least four carbon repeat units, wherein the admixtures form a self-organized periodic structures with periodicity of 10 to 200 A, where at least 50 %, preferably at least 70 %, in particular at least 90 %, of the initial of the weight the hydrogen bonding compound can be removed.

3. Film according to claim 1, prepared from an intermediate product comprising at least one conjugated nitrogen-containing polymer, at least one protonating compound, and at least one hydrogen bonding compound consisting of at least one nonpolar tail comprising at least four carbon, silyl, or halogenated repeat units in total, wherein the admixtures form a self- organized periodic structures with periodicity between 3-200 A, which has been aligned so that using a X-ray scattering analysis using a 2-dimensional detector, at least 90 % of the total integrated intensity of X-ray reflection arising from this periodicity is within the angular cone of < 45 °, preferably < 25 °, in particular < 15 °.

4. Film according to any of claims 1 to 3, which comprises polymers containing pyridine groups and has length of at least four repeat units.

5. Film according to claim 4, wherein the protonating compound is a sulfonic acid.

6. Film according to claim 5, wherein the hydrogen bonding compound is an alkyl phenol, comprising one, two or three hydroxyl groups and one or more alkyl groups with a length of at least four carbon units.

7. Film according to claim 6, wherein the hydrogen bonding compound is a alkyl dihydroxy benzene or alkylphenol.

8. Film according to claim 7, wherein the protonating agent is camphor sulphonic acid.

9. Film according to claim 8, wherein the hydrogen-bonding compound is hexyl resorcinol. pentyl resorcinol, or octyl phenol.

10. Film according to claim 1, exhibiting polarized emission where at least 90 % of the total luminance is emitted in the angular cone < 65°.

11. Film according to claim 1, exhibiting polarized emission where luminance parallel to the polymer chains and perpendicular to them differs by a multiplicative factor of at least 2.

12. Film according to claim 1, exhibiting polarized emission where luminance parallel to the polymer chains and perpendicular to them differs by a multiplicative factor of at least 4.

13. Method of producing an oriented polymer material having aligned polymer chains, comprising the steps of - providing a rigid-rod-type polymer material having a polymer chain with hydrogen bonding sites;

- contacting the rigid-rod-type polymer with a monomeric compound capable of forming hydrogen bonding with the hydrogen bonding sites of the polymeric chain of the polymer to form a modified polymer material comprising comb-shaped supramolecules;

- orientating the comb-shaped supramolecules of the modified polymer material to provide to an oriented modified polymer material; and optionally

- removing the hydrogen-bonded monomeric compounds to produce an oriented rigid-rod-type polymer material.

14. The method according to claim 13, wherein the rigid-rod-type polymer material comprises a conjugated aromatic polymer, having hetero atoms in the aromatic rings and/or in chains joining the rings.

15. The method according to claim 14, wherein the hydrogen bonding sites are generated by forming a protonated complex at the hetero atoms.

16. The method according to claim 15, wherein the protonated complex is formed by reacting the polymer with an acid having a pKa of less than 0.

17. The method according to claim 16, wherein the acid has the formula IV O

II HO-S— R II O

wherein R is hydrogen, or a linear or branched alkyl group having 1 to 12 carbon atoms, or an alicyclic group containing 5 to 8 carbon atoms or a aryl group, said alkyl, alicyclic or aryl group optionally bearing at least one substituent selected from lower alkyl, halo and hydroxy groups.

18. The method according to claim 17, wherein the acid is selected from the group of camphor sulphonic acid, methane sulphonic acid and p-toluene sulphonic acid.

19. The method according to any of claims 13 to 18, wherein the polymer having hydrogen- bonding sites is reacted with an amphiphilic compound comprising polar functionality and non-polar functionality.

20. The method according to claim 19, wherein the amphiphilic compound comprises a phenol having one, two or three hydroxyl groups.

21. The method according to claim 20, wherein the phenol has at least one hydrocarbon substituent comprising a linear or branch alkyl or alkenyl group having 2 to 12 carbon atoms, preferably an alkyl group having 4 to 8 carbon atoms, said alkyl or alkenyl group optionally being substituted.

22. The method according to claim 21, wherein the phenol is hexyl resorcinol or pentyl resorcinol.

23. The method according to any of claims 13 to 22, wherein the rigid-rod-type polymer comprises a π-conjugated polymer or oligomer backbone, containing repeating units selected from:

wherein each of Ri to R_t is independently hydrogen, a linear or branched alkyl having 1 to 20 carbon atoms, or an aryl group which may be optionally substituted by at least one substituent selected from lower alkyl (C1-C6 alkyl), halo and hydroxy groups.