WO1999014255A1

WO1999014255A1 - Poly(aryl vinylene)s

Info

Publication number: WO1999014255A1
Application number: PCT/GB1998/002800
Authority: WO
Inventors: Julian Outfin Williams; Olayinka Olufemi Jameson Pearse; Eric Thwaites; Franz Stelzer; Berthold Winkler; Gunther Leising; Ruth MÜLLNER
Original assignee: White Knight Technologies Limited
Priority date: 1997-09-16
Filing date: 1998-09-15
Publication date: 1999-03-25
Also published as: GB2346374B; GB0005997D0; AU9089198A; GB2346374A; EP1012201A1

Abstract

Poly(9,10-anthrylene vinylene)s, including substituted derivatives thereof, preferably having in excess of seven anthrylene units in each polymer chain are synthesised by polymerising a dibenzobarrelenes using a metal catalysed ring-opening olefin metathesis polymerization (ROMP) reaction under oxygen-free conditions. The anthrylene units in the resulting poly(9,10-dihydro-9,10-anthrylene vinylene) may be totally or partially 9,10-dehydrogenated using heat or an oxidising agent such as DDQ.

Description

POLY(ARYL VINYLENE)S

TECHNICAL FIELD OF THE INVENTION

This invention relates to the synthesis of poly(aryl vinylene)s. More particularly, the invention is concerned with the synthesis of poly(9,10- dihydro-9,10-anthrylene vinylene)s, partially hydrogenated poly(9,10- anthrylene vinylene)s and poly(9,10-anthrylene vinylene)s, including substituted derivatives thereof.

BACKGROUND

Poly(arylene vinylene)s of the general structure [-Ar-CH=CH-]_n, where Ar denotes an arylene unit, can be useful as "molecular wires". Many such polymers are known to exhibit electroactive properties and are capable of conducting electricity along the molecular chain without leakage of electrons {i.e. the polymeric molecules exhibit inherent electrical insulation) so that they can form extremely thin electrical conductors. In some cases the polymeric molecules can possess charge storage properties, making them potentially useful in the construction of electrical batteries and capacitors for example. It is also known that poly(arylene vinylene)s can exhibit electro- optical properties, e.g. electroluminescence, so that they can, for example, be used in the construction of light emitting diodes and flat screen display devices.

Poly(anthrylene vinylene)s and related polymers are likely to prove particularly useful materials due to the characteristics imparted into the macromolecule by the incorporation of the anthracene unit.

K. Mullen et al. have attempted to synthesise poly(9,10-anthrylene vinylene)s from various 9,10-substituted anthracenes using a variety of reactions including the Horner-Emmons modification of the Wittig reaction, but they found no tendency towards polymerisation attributed in all cases to steric crowding at the reaction centre and, in the case of the Wittig reaction, inordinate stability of the ylide intermediate (Makromol. Chem., 1990, 191 , 2815.) Limited success was achieved using step-wise synthesis, which resulted in the construction of oligomers containing not more than seven [9, 10-anthrylene vinylene] subunits. The electroactive properties of such oligomers was further investigated (idem; ibid, 1992, 193, 81).

K. Mullen et al have already described a process for the synthesis of poly(1,4-anthrylene vinylene)s using the Wessling-Zimmerman precursor polyelectrolyte route (Macromolecules, 1994, 27, 1922). However, the process described by Mullen was not capable, due to the formation of stable, non-polymerizable intermediates, of yielding poly(9,10-anthrylene vinylene)s, which potentially have superior electro-optical properties. The present invention seeks to provide a new and inventive process for the synthesis of poly(aryl vinylene)s, and more particularly poly(9, 10-anthrylene vinylene)s and related polymers.

SUMMARY OF THE INVENTION

The present invention proposes a method of forming a poly(aryl vinylene), characterised by polymerisation of monomeric precursor material comprising dibenzobarrelene (i.e. 9,10-dihydro-9,10-ethanoanthracene) or a substituted derivative thereof.

Except where the context requires otherwise herein, the terms "polymer", "poly-", "polymeric" and similar terms derived therefrom should be understood to embrace both oligomers and copolymers.

The dibenzobarrelene monomeric precursors can readily be prepared by various known methods of synthesis. Some selected references, which describe the synthesis of dibenzobarrelenes are:

H . Figeys and A. Dralants; Tetrahedron, 1972, 28, 3031. T. Ohwada, I. Okamoto, N. Haga and K. Shudo; J. Org. Chem., 1994, 59, 3975.

The precursor material is preferably polymerised by alkene metathesis, e.g. in the presence of a metal containing catalyst such as a known organomolybdenum initiator. The form of alkene metathesis known as the ROMP reaction (Ring-opening Olefin Metathesis Polymerisation) has previously been described in detail by R. H. Grubbs et al; Science, 1989, 243. 907, and R. R. Schrock; Ace. Chem. Res., 1990, 24, 158. An initiator such as those discussed below can advantageously be present.

The method results in the synthesis of a poly(9,10-dihydro-9,10- -anthrylene vinylene), which can be substituted or unsubstituted depending on whether the dibenzobarrelene in the precursor material possesses any substituent groups. The method of synthesis of this intermediate or "precursor" polymer is relatively easy to perform and gives a high yield of product. The polymerisation reaction generally proceeds at quite a slow rate so that the reaction can be terminated in a controlled manner (see below) to yield a poly(9,10-dihydro-9,10-anthrylene vinylene) oligomer, polymer or copolymer of the required chain length.

The precursor polymer poly(9,10-dihydro-9,10-anthrylene vinylene) can be either fully dehydrogenated at the 9,10-positions of the anthrylene moieties giving a poly(9,10-anthrylene vinylene) or incompletely dehydrogenated to give a partially hydrogenated poly(9,10-anthrylene vinylene). The dehydrogenation of the 9,10-dihydro-9,10-anthrylene units of the precursor polymer to produce the 9,10-anthrylene moieties can be effected by known means, e.g. heating or chemical methods such as suitable oxidising reagents.

Poly(9,10-dihydro-9,10-anthrylene vinylene)s, poly(9,10-anthrylene vinyl- -ene)s, and partially hydrogenated poly(9,10-anthrylene vinylene)s and substituted derivatives thereof are also claimed perse.

GENERAL CASE

A precursor dibenzobarrelene monomer is produced by known means, having the general formula (i)

where: R^1-12 = hydrogen or any substituent group. By way of example, the substituents R^1-12 may comprise any combination

of hydrogen, halogen, alkyl (e.g. methyl, ethyl, t-butyl, rz-pentyl, etc.), haloalkyl, aryl, alkoxy, aryloxy, nitro, cyano, thiocyanate, ketone, ester, silyl, silyloxy, acyloxy or carbonate groups.

Any two or more of the R substituents may be the same. Also any pair or combination of pairs of the R substituents may comprise the termini of a ring system or fused ring systems, for example:

(a) carbocyclic or heterocyclic aromatic rings, e.g. benzene or pyridine rings.

(b) carbocyclic or heterocyclic fully unsaturated rings or partially unsaturated rings.

The dibenzobarrelene is polymerised under inert, oxygen free conditions by means of a ROMP reaction using a suitable initiator, such as a Schrock initiator, e.g. [Mo(=NAr)(=C(H)CMe₃)(OCMe(CF₃)₂)₂], where Ar denotes 2,6-diisopropylphenyl. This yields a poly(9,10-disubstituted-9,10- anthrylene vinylene) precursor polymer of the general formula (ii)

where R^{1 12} is as defined above, and n is the number of monomeric subunits in any given polymer and may vary from molecule to molecule within the bulk material.

The structure of the vinylic link may be either cis or trans, as denoted by wavy bonds (_*««•). The ratio of cis- to trans- vinylic links may, inter alia, be influenced by the structure of the particular Schrock initiator chosen. For a discussion of this aspect of the ROMP reaction see, for example, the work of Grubbs et al.; Macromolecules, 1996, 29_, 1138. In general, however, in ROMP polymerisations of the type under consideration the number of f/ans- vinylic links formed predominates over the number of c/s-vinylic links The vinylic link may be constructed in three different ways:

(a) "Head-to-tail" as denoted in structure (ii)

(b) "Head-to-head" as denoted in structure (iii)

(c) "Tail-to-tail" as denoted in structure (iv)

Any given precursor polymer molecule may contain exclusively head-to- -tail vinylic links or alternatively may contain a mixture of head-to-tail head-to-head and tail-to-tail vinylic links, depending on the nature of R¹"¹². For a discussion of this type of phenomenon see K. J. Ivin and J. C. Mol; Olefin Metathesis and Metathesis Polymerisation", Academic Press, London 1997, p. 255.

Groups R⁹ and R¹⁰ are then eliminated from the precursor polymer, (ii) resulting in the rearomatisation of the anthrylene moieties and the formation of (v). In the case where R⁹ = R¹⁰ = H the 9,10-dihydro-9,10- anthrylene moieties of the precursor polymer can be dehydrogenated. This can be effected by various means including heating the precursor polymer and/or chemical means such as the use of an oxidising reagent, e.g. 2,3-dichloro-5,6-dicyano-1 ,4-benzoquinone (DDQ). For a review of the application of DDQ in organic synthesis see:

D. Walker and J. D. Hiebert; Chem. Rev., 1967, fiZ, 153.

References, which describe the oxidative dehydrogenation of similar precursor polymers, are:

L. Pu, M. W. Wagaman and R. H. Grubbs; Macromolecules, 1996, 2a, 1138.

M. W. Wagaman and R. H. Grubbs; Macromolecules, 1997, 20_, 3978.

This dehydrogenation results in rearomatization of the 9,10- -dihydroanthrylene moieties to give a poly(9,10-anthrylene vinylene) polymer of the general formula (v)

where R¹"⁸ and R¹¹ _' ¹² and n are defined as above and for simplicity of explanation only the case of a head-to-tail link is depicted, since the mode of dehydrogenation of both the possible head-to-head cases (iii and iv) are precisely analogous.

Alternatively, by using less than one equivalent of the oxidising reagent, precursor polymer (ii) can be converted into a partially dehydrogenated polymer represented by the general formula (vi) , which can either constitute a final product or an intermediate suitable for further dehydrogenation.

(vi)

where R⁹ = R¹⁰ = H and where R¹-⁸ and RX¹2 are as defined above and where formula (vi) illustrates a typical segment of a partially dehydrogenated polymer chain, rather than a specific repeating unit. A given precursor polymer (ii; R⁹ = R¹⁰ = H) consisting of n [9,10-dihydro- -9,10-anthrylene vinylene] subunits might, after partial dehydrogenation, consist of m [9,10-anthrylene vinylene] subunits and (n - m) [9,10-

-dihydro-9,10-anthrylene vinylene] subunits. Depiction of possible head- to-head and tail-to-tail isomerism in formula (vi) are omitted in the interests of simplicity of explanation.

The following examples are not intended to limit the invention in any manner, but merely are provided for the purposes of illustrating the above-described invention. EXAMPLE 1 : SYNTHESIS OF POLY(2-CHLORO-9,10-DIHYDRO-9,10- -ANTHRYLENE VINYLENE) IN OLIGOMERIC FORM

The precursor dibenzobarrelene monomer 2-chloro-9,10-dihydro-9,10- ethenoanthracene having formula (vii) can be readily produced by known means from 2-chloroanthracene (see above references), although the sample used was purchased in racemic form from Sigma-Aldrich Chemical Co Ltd.

(vii)

The monomer (vii) was polymerised in a nuclear magnetic resonance (NMR) spectrometer sample tube under oxygen-free conditions in deuterated benzene solution at a temperature of 18 °C using the Schrock initiator of the formula (viii) [Mo(=NAr)(=C(H)CMe₃)(OCMe (CF ₃)₂)2], where Ar is 2,6-diisopropylphenyl, see R. R. Schrock et al.; J. Am. Chem. Soc, 1990, H2, 3875.

(viii)

After a period of 20 hours this process yielded the precursor oligomer poly(2-chloro-9,10-dihydro-9,10-anthrylene vinylene) of the formula (ix)

(ix)

where n = 5 best corresponded to the estimated average chain length of the oligomer. The rate of polymerisation might be regarded as comparatively slow, but this does confer a number of practical advantages, especially since oligomers as well as polymers can be generated in a controlled fashion by this process. The significance of this aspect of reaction rate is discussed below.

It may also be noted that in structure (ix) the c/s-9,10-dihydroanthrylene hydrogens are shown lying below the plane of the page with pairs of hashed bonds ( ) they might equally as well be depicted with pairs of wedged bonds (— ■) projecting out of the plane of the page, since the starting monomer (vii) is racemic. This principle also applies to all such similar cases e.g. precursor polymer (xvi) in Example 2.

With respect to the 2-chloro substituent the possibility exists for the formation of head-to-tail (ix), head-to-head (x) and tail-to-tail (xi) vinylic links.

(x) (xi)

For simplicity of explanation the oligomeric poly(2-chloro-9,10-dihydro- -9,10-anthrylene vinylene) is subsequently referred to in this text by only the structure number (ix), wherein the incorporation of possible head-to- head and tail-to-tail links within a given chain is implied.

Subsequent dehydrogenation of oligomer (ix) was not undertaken since the primary objective of preparing this soluble precursor oligomer was to carry out proton nuclear magnetic resonance studies to examine the structure of (ix) and to ascertain, as far as possible, that polymerisation of monomer (vii) had indeed taken place by a true ring opening olefin metathesis reaction to give oligomer (ix). The outcome of these ¹H -NMR investigations is discussed below.

In more detail, in a nitrogen filled glove box 2-chloro-9,10-dihydro-9,10- ethenoanthracene (vii) (30.6 mg, 0.128 mmol) was dissolved in benzene- -d₆ in an NMR sample tube. To this solution was added the initiator 2,6- -diisopropylphenylimido neopentylidenemolybdenum bis(hexafluoro-f- butoxide) (viii) (18 mg). The reaction was allowed to proceed at ambient temperature (18 °C) for 20 hours. The progress of the reaction was monitored by 90 MHz ¹ H-NMR spectroscopy.

After 20 hours the ¹ H-NMR spectrum indicated the formation of (ix) in the form of an oligomer, where the estimated average chain length corresponded to a value of n = 5, based on approximate integration of the final ¹ H-NMR spectrum (Fig. 3) and knowledge of the molar ratio of initiator to monomer at the start of the reaction.

Figure 1 shows the 400 MHz ¹ H-NMR spectrum of the starting monomer (vii) in the absence of any initiator (viii) : δ_H 7.3-6.9 (broad complex multiplet, 7H aryl and 2H vinyl), 5.1 (multiplet, 2H bridgehead).

Figure 2 shows an expansion of the 90 MHz ¹ H-NMR spectrum of the initiator (viii) at the start of the reaction in the region 11-13 ppm, a salient feature of which is the singlet at δ_H 12.1 , assigned to the initiator Mo- carbene proton, see R. R. Schrock; op. cit.

Figure 3 shows the 90 MHz ¹ H-NMR spectrum of the reaction mixture after 20 hours. Salient features of the spectrum include: δ_H 12.2-12.5 (broad multiplet, carbene proton of Mo-polymer), 12.1 (singlet, carbene proton of Mo-initiator), 6.4-7.5 (broad multiplet, aryl protons of polymer and aryl protons of initiator) 5.2-5.8 (broad singlet, vinyl protons of polymer), 3.9-4.4 (broad singlet, allyl protons of polymer), 3.5 (multiplet, methine protons of isopropyl groups of initiator), 1.0-1.4 (broad complex multiplet, various methyl groups of initiator).

Figure 4 shows an expansion of the 90 MHz ¹ H-NMR spectrum of the of the reaction mixture after 20 hours in the region 11 -13 ppm, a salient feature of which is a broad complex multiplet between δ_H 12.2-12.5, which can be assigned to the polymer Mo-carbene proton, see formula (xii; R = Cl). The complexity of this signal can be attributed primarily to vicinal spin-spin coupling of the polymer Mo-carbene proton with the allylic proton of the neighbouring 9,10-dihydroanthrylene moiety and secondarily to long range coupling with some of the aromatic protons of this dihydroanthrylene moiety, while the broadening may be attributable to changes in orientation of the adjacent dihydroanthrylene group. The singlet at δ_H 12.1 , can be assigned to Mo-carbene protons associated with those molecules of the Schrock initiator (viii) that escaped reaction with the monomer (vii). The strength of the signal at δ_H 12.1 can be seen to have decayed markedly in comparison to its appearance at the start of the reaction as shown in Fig. 2, indicating that a majority of the initiator molecules have reacted with molecules of monomer. Integration of the signals in Fig. 4 indicates that the ratio of polymer Mo-carbene protons to initiator Mo-carbene protons is approximately 6 : 1.

(xii) where R = Cl and where -^■ *- indicates vicinal spin-spin coupling and

^■*^■- --^■*^■ indicates long range spin-spin coupling. Structure (xii; R = Cl) shows the structure of the polymer after n turnovers of the ROMP polymerisation of monomer (vii) initiated by Schrock initiator (viii).

Species like (xii) with appreciable life spans generally behave as "living polymers", (K. J. Ivin and J. C. Mol; op. cit., p 233). Such living polymers can undergo subsequent polymerisations either by adding a further quantity of the original monomer or by adding a different monomer. The latter case results in the formation of a block copolymer. Living polymers derived from Mo-carbene initiators are best terminated by reaction with an aldehyde. Termination with di- and tri-aldehydes can, in principle, lead to polymer molecules with double or treble the molecular weight of the original living polymer (P. Dounis and W. J. Feast; Polymer, 1996, 26., 2787). Various ways of synthetically exploiting living polymers like (xii) are discussed below.

EXAMPLE 2: SYNTHESIS OF POLY(2-ETHYL-9,10-ANTHRYLENE VINYLENE)

The precursor dibenzobarrelene monomer 2-ethyl-9,10-dihydro-9,10- -ethenoanthracene having formula (xiii) was prepared in racemic form by known methods from 2-ethylanthracene (see above references).

(xiii)

Monomer (xiii) was polymerised under oxygen free conditions in anhydrous toluene at 33 °C using Schrock initiator (viii). After 3 days the reaction was quenched with benzaldehyde, which after removal of the solvent and precipitation with methanol afforded the precursor polymer poly(2-ethyl-9,10-dihydro-9,10-anthrylene vinylene) (xiv) as a greenish to light brown solid in approximately 82% yield for this step.

(xiv)

The precursor polymer (xiv) was dehydrogenated by reaction with DDQ to give the fully aromatised polymer poly(2-ethyl-9,10-anthrylene vinylene) (xv) as an orange solid in approximately 84% yield for this step.

(xv)

where 20 s*« 5=30, as measured by gel permeation chromatography (GPC).

Formulae (xiv and xv) imply the possiblity of cis/trans isomerism with respect to the vinyl links and head-to-tail, head-to-head and tail-to-tail isomerism with respect to the ethyl groups, as discussed above for general case (ii) and the specific case (ix).

In more detail, in a nitrogen filled glove box a small, rigorously dried, flask was charged with degassed 2-ethyl-9,10-dihydro-9,10-ethenoanthracene (xiii) (207 mg, 8.91 x 10-⁴ moles), to which was added 2,6- diisopropylphenylimido neopentylidenemolybdenum bis(hexafluoro-f- -butoxide) (viii) (28.5 mg, 4.40 x 10"⁵ moles) dissolved in anhydrous toluene (0.3 ml). The resultant solution was then diluted by the addition of a further quantity of toluene (0.5 ml). The flask was stopperred and carefully sealed with "Parafilm" (self sealing laboratory film manufactured by American National Can Co). The sealed flask was then removed from the glove box and the reaction mixture was maintained at approximately 33 °C for three days by partial immersion of the flask in a heated oil bath. The reaction was then quenched by the addition of four drops of benzaldehyde. The toluene was removed by distillation at reduced pressure and the solid residue was redissolved in dichloromethane. This solution was then slowly poured dropwise into methanol precipitating the polymer as filaments. The methanolic solution was stirred in order to ensure homogeneity, then centrifuged. After centrifugation the supernatant liquid was removed by decanting and the solid residue redissolved in dichloromethane. The above procedure was repeated twice. After the final precipitation with methanol the mixture was stored at 0 °C for two days prior to ultimate separation. After decanting off most of the methanol the solid residue was dried under high vacuum. This afforded the precursor polymer poly(2-ethyl-9,10-dihydro-9,10-anthrylene vinylene) of the formula (xvi) as a green to light brown solid (170 mg) in approximately 82% yield for this step.

(xvi)

Because of the difficulty in removing unreacted DDQ less than one equivalent of this reagent was employed in the initial dehydrogenation step. Polymer (xvi) (71.5 mg, 3.08 x 10"⁴ moles) was dissolved in dichloromethane (2 ml). 2,3-Dichloro-5,6-dicyano-1 ,4-benzoquinone (DDQ) (32.6 mg, 1.37 x 10"⁴ moles) was dissolved in dichloromethane (2 ml). The two solutions were combined and stirred for one hour at ambient temperature, during which time the colour of the reaction mixture became deep red to brown. The polymer was precipitated by pouring into methanol and the resultant suspension was centrifuged. After centrifugation the supernatant liquid, which contained the by-product 2,3-dichloro-5,6-dicyanodihydroquinone (DDQH₂), was removed by decanting and the solid residue redissolved in dichloromethane. The above procedure was repeated once. After final removal of the supernatant liquid by decanting the solid residue was dried under high vacuum. This afforded the partially dehydrogenated polymer illustrated by formula (xvii) as an orange solid (60 mg) in approximately 84% yield for this step.

(xvii)

where formula (xvii) illustrates a typical segment of the partially dehydrogenated polymer, rather than a specific repeating unit. The [2- ethyl-9,10-anthrylene vinylene] and [2-ethyl-9,10-dihydro-9,10-anthrylene vinylene] subunits would be distributed at random along the length of a given polymer chain. A given precursor polymer (xvi) consisting of n [2-ethyl-9,10-dihydro-9,10-anthrylene vinylene] subunits might, after partial dehydrogenation, give a partially converted polymer (xvii) consisting of m [2-ethyl-9,10-anthrylene vinylene] subunits and (n - m) [2-ethyl-9,10-dihydro-9,10-anthrylene vinylene] subunits.

Such partially dehydrogenated polymers as exemplified by the specific case (xvii) and by the general case (vi) are claimed as part of the invention. Complete dehydrogenation of a small quantity of partially dehydrogenated polymer (xvii) was effected by treatment with an excess of DDQ. Using a similar procedure to that described above, polymer (xvii) (30 mg) and DDQ (30 mg) were allowed to react in dichloromethane solution giving eventually a deep red colour. After a similar work up procedure to that described above, the resultant solid product was washed twice with methanol, to remove any last traces of DDQH₂ and unreacted DDQ, and dried under high vacuum. This afforded the fully dehydrogenated polymer poly(2-ethyl-9,10-anthrylene vinylene) of the formula (xviii) as an orange to brown solid in quantitative yield for this step.

(xviii)

where 20 s* n s≥30, as measured by GPC, and as discussed below.

Physical characterisation of polymer (xviii) was carried out and the results compared with the starting monomer (xiii) . However, NMR analysis of (xviii) was precluded by the low solubility of this polymer in, for example, deuteriobenzene or deuteriochloroform. Such insolubility should be overcome by the use of a substituent longer than 2-ethyl, e.g. 2-n-pentyl or 2-n-hexyl, as demonstrated, in similar circumstances for poly(1 ,4-naphthylene vinylene)s (PNVs) by R. H. Grubbs et al. (op. cit., 1996). Comparison may be made between the results presented below and the experimental and theoretical studies of model oligomers of poly(9,10-anthrylene vinylene)s, carried out by K. Mullen et al.; Makromol. Chem., 1990, 19 2815; idem ibid., 1992, I L 81. These oligomers were prepared using inter alia the Wittig, Horner-Emmons and McMurry reactions rather than by ROMP polymerisation. Such methods appear to constitute step-wise syntheses rather than polymerisation processes, giving chain lengths not in excess of seven [9,10-anthrylene vinylene] subunits. The solubility of these oligomers was enhanced by Mullen with the use of strategically placed n-pentyl side chains in both the 2 and 3 positions of some of the anthrylene moieties.

The characterisations, described below, for polydispersity are derived from gel permeation chromatography (GPC), which uses a refractive index detector (Rl) as a nonspecific mass detector in size-exclusion chromatography. It should be noted that this method does not give the refractive index of samples, but rather reveals the molecular weight components and distribution of the monomer or polymer.

Figure 5 shows the Rl detection of the whole GPC run in chloroform for the ROMP polymerisation of the monomer (xiii) giving polymer (xiv). The data indicate that there are two peaks in the molecular weight (MW), which are relatively close in magnitude: the first peak (at 27.6 minutes) corresponds to the monomer (xiii) and the second peak (at 29 minutes) is due to the polymer (xiv).

Figure 6 shows an enlarged version of the GPC scan as described by Fig. 5, confined to the elution times 26.5 to 28.5 minutes, showing Rl- detection of monomer (xiii).

Figure 7 shows the UV-detection of the monomer (xiii) peak (the first peak in the Rl-detection case described in Fig. 5), which gives an absorption spectrum as a function of time of elution from the GPC. The UV-absorption peak at 260 nm indicates that this is a monomer due to the short wavelength. The UV-detection run is recorded only for the elution time of 26.5 to 28.5 minutes, which confines it to the monomer.

Figure 8 shows the UV spectrum of monomer (xiii) in chloroform at 260.9 nm and 27.585 ml, which are comparable with the UV data for dibenzobarrelene (9,10-dihydro-9,10-ethenoanthracene) obtained by H. P. Figeys and A. Dralants (op. cit).

Figure 9 shows the Rl detection of the whole GPC run in chloroform for the dehydrogenation of the precursor polymer (xiv) giving polymer (xv). The dehydrogenation process creates a broad peak centred at approximately 21 minutes, which corresponds to the dehydrogenated polymer (xv), while the second peak at 29 minutes is due to the presence of residual precursor polymer (xiv).

Figure 10 shows an enlarged version of the GPC scan as described by Fig. 9, confined to the elution times 16 to 26 minutes, showing Rl- detection of polymer (xv).

Figure 11 shows the UV-detection of polymer (xv) peak (the first peak in the Rl-detection case described in Fig. 9), which gives an absorption spectrum as a function of time of elution from the GPC. The UV- absorption peak at 400 nm is appropriate for a polymer of this type. The UV-detection run is recorded only for the elution time of 16 to 26 minutes, which confines it to this monomer.

Figure 12 shows the UV spectrum of polymer (xv) in chloroform at 260.9 nm and 21.181 ml, which are comparable with the UV data obtained for oligomers of poly(9,10-anthrylene vinylene)s obtained by K. Mullen (op. cit, 1990).

Figure 13 is included for comparison purposes and shows the UV spectra in hexane solution of the homologous series of aromatic hydrocarbons: benzene - naphthalene - anthracene, as adapted from W. Kemp; Organic Spectroscopy", 2nd edition, MacMillan, London, 1987, p. 203.

The GPC results were used to give a qualitative indication of the molar mass of the fully dehydrogenated polymer (xv). Using the polymer polystyrene (the internationally recognised reference material) as a standard, it was found approximately that (xv; 20 s= n s*30).

Figure 14 shows the photoemission spectra for polymer (xv) in chloroform solution and in poly(methyl methacrylate) (PMMA) matrix. The spectra show that polymer (xv) is photoluminescent. The emission band for polymer (xv) in solution is almost in the same position and of the same width as that obtained for polymer (xv) in the PMMA host. PMMA was used as a solid host so that the sample was maintained in a "solid solution". PMMA has the useful properties of being transparent in the visible region, avoids aggregation quenching and is relatively inert to the added chromophore. The long wavelength edge for the polymer in the PMMA matrix is at slightly shorter wavelengths than for the solution. The peak emission occurs at 520 nm with the band extending from approximately 430 nm to 660 nm.

Quantum efficiency for photoluminescence is defined thus:

Number of photons emitted Quantum efficiency =

Number of photons absorbed

and represents a measure of the efficiency of the material in producing photoluminescence. For polymer (xv) the quantum efficiency was calculated as between 3 to 4%. This relatively low value is indicative of the intervention of significant non-radiative processes. Methods of enhancing the photoluminescence quantum efficiency of polymer (xv) are discussed below.

Of particular relevance to the electro-optical properties of conjugated polymers such as (xv) is the band gap, E_g, between the valence and conduction bands, which represents the energy difference between the the highest occupied electronic molecular orbital and the lowest unoccupied electronic molecular orbital (the HOMO/LUMO gap). The value of the band gap, E_g, can be calculated from the equation:

he

-9 _g

where λ_g is the characteristic wavelength of the photoluminescence, ft is Planck's constant and c is the speed of light.

For polymer (xv) Fig. 14 shows that the emission peak gives

λ._g(xv₎ *» 520 nm.

=> E_g(xv) «* 3.9 x 10"¹⁹ Joules

=> E_g(xv) ~ 2.37 eV

It must be noted that this value of 2.37 eV for the band gap associated with polymer (xv) represents a first approximation and, to obtain a more accurate value, consideration should be given to the width and shape of the emission band (430 < λ_g(W) < 660 nm).

The value of Eg_(xv) ^«* 2.37 eV is in good agreement with the values, based on both cyclic voltametry and UV absorption spectroscopy, obtained for poly(9,10-anthrylene vinylene) oligomers by Mullen (op. cit., 1990). The latter method gave by process of extrapolation E_g «* 2.34 eV (chain length n s» 7). Mullen observed that this value lay slightly lower than the known value for poly(p-phenylene vinylene) (PPPV) at 2.4 - 2.5 eV (H. -H. Horhold and H. Helbig; Makromol. Chem., Macromol. Symp., 1987, 12, 229), so that comparable electrical conductivity for suitably doped poly(9,10-anthrylene vinylene) polymers might be expected.

The somewhat low value for the quantum efficiency (3 to 4%) for the photoluminescence of polymer (xv) could be increased by a number of methods. Firstly, the polymer could be used in a partially dehydrogenated form similar to polymer (xvii). Grubbs states (op. cit. 1997) in the analogous case of poly(2,3-bis((methoxy)carbonyl)phenylene vinylene) that it was sometimes desirable for the polymer to be only partially aromatised since this conferred a higher photoluminescence quantum yield. Partial aromatisation of a given precursor polymer is achieved by using less than one equivalent of the oxidising agent DDQ. Employing such a strategy would create a larger number of chromophores than was the case for polymer (xv), since, within a given chain of polymer (xvii), the chromophores consisting of contiguous, fully conjugated, aromatised [poly(9,10-anthrylene vinylene)] subunits would be isolated from each other by the interpolation of [9,10-dihydro-9,10-anthrylene vinylene] subunits, thus giving rise to more, but shorter, individual chromophores.

In such cases the shortening of the conjugated segments enhances the quantum yields for both photoluminescence and electroluminescence, probably originating from a reduction of nonradiative processes such as diffusion of the excited states to quenching sites (A. Kraft et al.; Angew. Chem. Int. Ed. Engl., 1998, 2Z, 402). It is known that, as the series of dihydro-derivatives of benzene, naphthalene and anthracene is ascended, 1 ,4-dihydrobenzene is relatively unstable towards thermally induced dehydrogenation, and 1 ,4-dihydronaphthalene is moderately stable, but 9,10-dihydroanthracene is a stable compound (m.p. 108-110 °C, b.p. 312 °C) (G. M. Badger; "Aromatic Character and Aromaticity", Cambridge University Press, Cambridge, 1969, p. 20). This observation bodes well for the thermal stability of the precursor polymer (xv) and the partially dehydrogenated polymer (xvii), which both contain 9,10- -dihydroanthrylene moieties. Secondly, the use of long branched side chains attached to the phenyl moiety of substituted PPPVs has been shown to increase electroluminescence efficiency. Thus it might be expected that the use of a long branched chain rather than the ethyl substituent of polymers (xv) or (xvii) should improve their quantum yields for both photoluminescence and electroluminescence. Thirdly, the formulation of a "solid solution" of fully dehydrogenated polymer (xv) or partially dehydrogenated polymer (xvii) in, for example, a poly(vinyl)carbazole (PVK) matrix might be expected to improve their quantum yields for both photoluminescence and electroluminescence. If an electroactive polymer such as PVK is blended with tiny amounts of luminescent material, the resultant substance can be fabricated into quite bright electroluminescent devices (C. Zhang et al.; Synth. Met, 1995, Z£, 185; F. Garten et al.; Appl. Phys. Lett., 1995, 6J 2540; A. Kraft etal.; op. cit, 1998). Furthermore, in some cases, embedding conjugated polymers in a PVK matrix has been shown to shift both their photoluminescence and electroluminescence peak frequencies markedly towards the blue end of the electromagnetic spectrum (H. N. Cho et al.; Macromol Symp., 1997, 125, 133; F. Garten et al.; op. cit).

Polymer (xv) was experimentally tested for photoconductivity. It was found that, while the polymer itself absorbed only in the UV-region, its presence in blends enhanced the photoconductivity of other materials by several orders of magnitude. These experimental results indicate a potential application for polymers such as (xv) in the fabrication of photovoltaic cells and similar devices.

A further important aspect of polymer (xv) is the expected electronic charge storage capability of the 9,10-anthrylene subunits. It is known that anthracene as well as ,ω-dianthrylalkanes accept two and four negative charges, respectively, when reduced with alkali metals (K. Mullen et al.; Angew. Chem., 1983, 25_, 239). Oligomer studies by Mullen (op. cit; 1990) showed that reduction of di(9,10-anthrylene vinylene) (xix) with lithium or potassium gave the expected tetraanion (xx) as shown in Scheme 1. The reduction process was monitored by 200 MHz ¹ H-NMR, and augmented with cyclic voltametry studies. Analogously tri(9,10- -anthrylene vinylene) (xxi) could be similarly converted to a hexaanion. In both cases the nature of the anionic species was confirmed by quenching experiments with dimethyl sulphate.

Tetraanion

Schemel

Hexaanion

Schemel

(continued)

The reduction of the higher oligomers including the heptamer were found by Mullen to proceed in analogous fashion, as judged by quenching experiments.

On the basis of Mullen's oligomer studies it may be predicted that polymers of the type exemplified by (xv) should possess remarkably good charge storage properties. These properties should make such polymers as (xv) useful components in electrical storage batteries.

For the majority of known conjugated polymers tested in electroluminescent devices, electron injection has proved to be more difficult than hole injection, that is to say the polymers are more easily oxidised than reduced. This has necessitated the use of metals with a low work-function (especially calcium) as the cathode material. Unfortunately calcium is highly susceptible to atmospheric degradation. Although this can be retarded by encapsulation, it would be beneficial to use less moisture and oxygen-sensitive cathode materials. If the barrier for electron injection from such materials is to be lowered , the polymer must be such that the energy of its LUMO matches the work function of the cathode (A. Kraft; op. cit). Given the good electron affinity of poly(9,10-anthrylene vinylene)s as demonstrated by Mullen's oligomer studies (Mullen; op. cit, 1994, 1992 and 1990), it might be expected that such polymers as (xv) would be good acceptors of electrons by injection from cathodes in electroluminescent devices.

The ROMP polymerisations of dibenzobarrelene monomers (vii) and (xiii) are slow compared to similar polymerisations of more highly strained bridged bicyclic olefins such as norbornene (K. J. Ivin and J. C. Mol; op. cit, Chapter 11 ). However, the slowness of the polymerisation does confer a number of practical advantages. In particular, it is possible to exert a degree of control over the molecular weight of the resultant polymer, by adjusting the molar ratio of monomer to initiator, allowing the synthesis of either oligomers or true polymers as desired. Molecular weight control is also useful in the preparation of copolymers, discussed below. If required, the rate of the ROMP reaction could be increased by the use of a "catalyst activator" such as hexafluoro-terf-butanol, as employed in a similar situation by Grubbs (op. cit; 1997) to produce a tenfold increase in reaction rate. Grubbs also found that the addition of tetrahydrofuran (THF), a Lewis base which coordinates with the molybdenum atom, promoted full initiation of the Schrock catalyst because it slowed propagation more than initiation. Achieving full initiation is desirable in order to obtain a well controlled polymerisation and to facilitate the synthesis of well defined block copolymers. Grubbs also found that the presence of THF not only produced full initiation at low monomer to initiator ratios, but also resulted in the synthesis of polymers with lower polydispersities.

If desired, the chain lengths of the precursor polymers such as (xiv) , produced by the process, can be increased by a number of methods. Firstly the monomer to initiator ratio can be increased. Secondly, as discussed above, the ROMP reaction can be quenched with a dialdehyde. Electronic through conjugation along the polymer chain can be preserved, if an aromatic dialdehyde such as (xxiii) or (xxiv) is employed.

(xxiii)

(xxiv) The twofold quenching process would proceed as shown in Scheme 2:

(xxiv)

Scheme 2

(xxv)

Scheme 2

(continued) Oxidation of the precursor polymer (xxvi) with, for example, an excess of DDQ gives the fully conjugated homopolymer (xxvii), containing (B + B ' + 1) [9,10-anthrylene vinylene] subunits.

Although the photochemical properties of polymer (xv) were not enhanced by increasing the value of n beyond 30, an increase in overall chain length would be advantageous for the fabrication of an electrically conducting polymer, suitably doped with, for example, 4-(diethylamino)- -benzaldehyde diphenylhydrazone, PVK, or Fullerene (C₆₀).

The solubility of precursor polymers such as (xiv) , partially dehydrogenated polymer (xvii) and fully dehydrogenated polymer (xv) can be enhanced by the use of a longer side chain than ethyl. Mullen (op. cit; 1990) has used n-pentyl substituents to achieve this objective with oligomeric poly(9,10-anthrylene vinylene)s. Good solubility of polymers such as (xiv), (xvii) and (xv) would facilitate their manipulation during device fabrication. The attachment of liquid crystal side chains (mesogens) (F. Stelzer et al.; Macromol. Chem. Phys., 1995, 196. 3623) or chiral side groups (R. H. Grubbs et al.; J. Am. Chem. Soc, 1991 , 113. 1704) are synthetic options for modifying the physical and electro-optical properties of polymers such as (xv) and (xvii).

Copolymers containing a combination of different arylene units can be much more versatile than homopolymers and can be chemically tuned to provide a wide variety of materials with considerably improved electroluminescent properties (A. Kraft; op. cit).

There are several ways of using the olefin metathesis reaction to generate copolymers (K. J. Ivin and J. C. Mol; op.cit, Chapter 14). Simultaneous ROMP copolymerisation of a dibenzobarrelene monomer such as (xiii) in the presence of another olefin monomer capable of undergoing metathesis polymerisation should produce a copolymer containing both monomer subunits interwoven along the polymer chain. Ideal candidates for such copolymerisations would be the barrelene compounds synthesised, from the biologically derived compound cyclohexa-3,5-diene-c/s-1 ,2-diol, by R. H. Grubbs (J. Org. Chem., 1997 , 62. 9076; op. cit, 1996 and 1997), some examples of which are shown below:

The efficient ROMP homopolymerisations of (xxviii) and (xxix) have already been demonstrated by Grubbs (op. cit, 1996 and 1997), using a molybdenum Schrock initiator similar to (viii).

Typically direct simultaneous copolymerisation of a monomer such as (xiii) with, for example, (xxviii) would lead to the formation of a precursor polymer, a segment of which would be described by structure (xxxi).

(xxxi)

where (xxxvi) represents a segment of a polymer chain rather than a specific repeating unit.

Partial or complete dehydrogenation of precursor copolymer (xxxi) could be effected by oxidation with, for example, DDQ.

Sequential addition of two or more monomers to a living metal carbene system yields a block copolymer. Although no direct evidence of the existence of the polymer-carbene-molybdenum system (xii; R = Et) is available, its formation in Example 2 is inferred by analogy with the NMR analysis of (xii; R = Cl). Scheme 3 shows the addition of monomer (xxix) to the living polymer (xii) to give living polymer (xxxii), to which is added monomer (xxx). The reaction is subsequently quenched by the addition of benzaldehyde to give the capped precursor polymer (xxxiii), which is an example of a triblock copolymer. Triblock precursor copolymer (xxxiii) is then ready for full or partial dehydrogenation by the usual methods. The sequence of addition of the monomers can be varied in order to give block copolymers of different composition.

(xxix)

i. (XXX) ii. PhCHO

Scheme 3

The synthesis of various other types of copolymer utilising the ROMP reaction are discussed at length by Ivin and Mol (op.cit, Chapter 14) including star-block, graft, comb, and statistical copolymers. Copolymerisation with monomers like divinyl benzene by means of acyclic diene metathesis (ADMET) polymerisation is yet another way of modifying the properties of the product polymer. All these techniques would appear to be applicable to polymerisations of dibenzobarrelene monomers such as (vii) and (xiii) in particular and as defined by (i) in general.

Thin-film transistors (TFTs) are emerging as important devices in the development of organic-based and printed electronic components and in the field of organic light-emitting diodes (OLEDs), rectifiers and capacitors. Applications for TFTs range from display drivers to electronically coded identification cards and other memory and logic elements. The most important material properties for the semiconductors that comprise the active materials in organic TFTs are high mobility, low "off-conductivity, stability, and processability. These attributes have been realised to some extent in p-channel (hole-transporting) materials, exemplified by a group of linear, conjugated molecules including thiophene oligomers, a benzodithiophene dimer, and pentacene. Other types of structures that show significant hole-transporting activity in TFTs include phthalocyanines and poly(alkylthiophenes). H. E. Katz et al. have synthesised the novel compound anthradithiophene (xxxiv; R = H) and some 2,8-dialkylated derivatives thereof (J. Chem. Soc, 1998, 120, 664).

where R = H, π-C₆H₁₃, J-C₁₂H₂₅ or />-C₁₈H₃₇ and the fused thiophene rings are represented as anti with respect to the sulphur atoms, but are actually prepared as syn/anti isomeric mixtures.

The alkylated anthradithiophene derivatives, in the form of polycrystalline organic films, were found by Katz to exhibit excellent, pentacene-like intrinsic mobility combined with greater solubility and oxidative stability.

The fused dithiophene dibenzobarrelene derivative (xxxv) could be prepared from anthradithiophene (xxxiv) by known means (see above references), and represents a member of the group of compounds defined by formula (i).

(xxxv)

where, for example, R = H, or alkyl and the fused thiophene rings are represented as defined above with respect to syn/anti isomerism. ROMP polymerisation of (xxxv) would lead to a precursor polymer of the formula (xxxvi)

(xxxvi)

where, for example, R = H, or alkyl and the fused thiophene rings are represented as defined above with respect to syn/anti isomerism.

Complete dehydrogenation of (xxxvi) would give rise to the fully aromatised polymer poly(anthrylenedithiophene vinylene) (xxxvi i), while incomplete dehydrogenation would afford a partially dehydrogenated polymer containing both (xxxvi) and (xxxvii) distributed at random within each chain, as discussed above for analogous cases.

The fused dithiophene dibenzobarrelene derivative (xxxv) could also be used to prepare copolymers in the various ways discussed above.

Polymers or copolymers containing (xxxvi) might be expected to embody, to some extent, the useful physical properties attributed by Katz et al. to alkylated anthradithiophene derivatives (xxxiv), as discussed above.

By way of comparison, poly(4,7-benzothiophene vinylene) (xxxvii) was prepared by P. M. Lahti et al., using the Wessling route, with a view to examining its electro-optical properties (J. Polym. Sci., Polym. Chem., Part A, 1994, 32, 65).

(xxxviii)

Polymer (xxxviii) was found by Lahti et al., using UV-VIS spectroscopic studies, to have a band gap of 2.92 eV.

Mullen discovered (op. cit, 1994) that treatment of film of poly(1 ,4- anthrylene vinylene) (xxxix) with a solution of the reactive dienophile N- phenyl-3,5-triazolinedione (XL) in chloroform resulted in a remarkable blue shift in the absorption maxima from 476 nm to a new maximum at 400 nm (c λ_max (PPPV) = 396 nm). Although the structure of the product (XL) of the solid state reaction could not be rigorously determined, it would seem likely that Diels-Alder cycloaddition had taken place across the 9,10- -positions of the anthrylene moieties, because with anthracene these are the most reactive centres towards dienophiles, as shown in Scheme 4.

(xxxix)

Scheme 4

Polymer (xLi) is fully conjugated, but the conjugated part now resembles PPPV, as is consistent with the UV data. Mullen felt the reaction held interest for the photonic applications of (xxxix), since it provided a way of structuring films of the polymer.

Analogous addition of a dienophile, for example (XL), to the generalised polymer (v) would give rise to polymer (XLi), as shown in Scheme 5. While polymer (XLi) is not conjugated the process would be useful as a means of chemically etching films of polymer (v) or otherwise modifying its physical properties. Polymer cross linking could be effected by using a reagent in place of (XL) consisting of molecules containing two dienophilic moieties linked together by an inert chain.

Scheme 5

Some organic materials have good potential for use in nonlinear optical devices because of their large optical nonlinearity and fast response time (D. S. Chemla and J. Zyss, eds.; "Nonlinear Optical Properties of Organic Molecules and Crystals", Academic Press, New York, 1987). In particular, organic thin films which exhibit third-order optical nonlinearity have many useful applications in integrated optics such as optical bistability, optical switching, and optical data processing. Delocalised τr-conjugated polymers usually have electrical conducting properties allied with high nonlinear optical susceptibility towards their chain directions. The third-order nonlinear optical susceptibility, χ⁽³⁾, of a thin film of PPPV was found to be 7.8 x 10^_12 esu, which was considered very high (T. Kaino et al.; Electron. Lett., 1987, 21, 1095). Similarly, the third- -order optical susceptibility, χ⁽³⁾, of a thin film of poly(2,5-dimethoxy p-phenylene vinylene) was found to be high at 5.4 x 10^-11 esu, indicating that the polymer was a promising material for nonlinear optical device fabrication (T. Kaino et al.; Appl. Phys. Lett., 1989, 54, 1619).

As pointed out by Mullen (op. cit, 1994), by selection of adequate topology, e.g. an 1 ,4-anthrylene moiety, an element of bidimensionality would be introduced into the monodimensional electronic structure of a poly(arylene vinylene) backbone, as compared with PPPV. On the basis of results obtained from PNV, this structural modification might be expected to favourably affect the magnitude and the response time of the third-order nonlinear optical signal. A similar argument could be used to predict useful third-order nonlinear optical properties for poly(9,10- anthrylene vinylene)s.

Whilst the above description lays emphasis on those areas which, in combination, are believed to be new, protection is claimed for any inventive information disclosed herein.

Claims

1. A method of forming a poly(aryl vinylene), characterised by polymerisation of monomeric precursor material comprising dibenzobarrelene or a substituted derivative thereof (i, vii, xiii xxxv).

2. A method according to Claim 1 , in which the precursor material is polymerised by alkene metathesis.

3. A method according to Claim 1 or 2, in which the precursor material is polymerised in the presence of a metal-containing catalyst.

4. A method according to Claim 3, in which said metal-containing catalyst is an organomolybdenum initiator.

5. A method according to Claim 4, in which said organomolybdenum initiator is 2,6-diisopropylphenylimido neopentylidenemolybdenum bis(hexafluoro-f-butoxide) (viii).

6. A method according to any of Claims 3 to 5, in which said precursor material is polymerised in the presence of a catalyst activator.

7. A method according to Claim 6, in which said catalyst activator is hexafluoro-fe/╧ä-butanol.

8. A method according to Claim 6, in which said catalyst activator is a Lewis base.

9. A method according to Claim 8, in which said Lewis base is tetrahydrofuran.

10. A method according to any preceding claim, in which the precursor material is polymerised under oxygen-free conditions.

11. A method according to any preceding claim, in which the polymerisation is terminated by introducing an aldehyde.

12. A method according to Claim 11 , in which said aldehyde is an aromatic aldehyde.

13. A method according to Claim 1 1 or 12, in which said aldehyde is a dialdehyde.

14. A method according to Claim 1 1 or 12, in which said aldehyde is a polyaldehyde containing three or more aldehyde groups.

15. A method according to any preceding claim, in which said dibenzobarrelene is 2-chloro-9,10-dihydro-9,10-ethenoanthracene (vii).

16. A method according to any of claims 1 to 14, in which said dibenzobarrelene is 2-ethyl-9,10-dihydro-9,10-ethenoanthracene (xiii).

17. A method according to any preceding claim, in which said polymerisation reaction yields a homopolymer.

18. A method according to any preceding claim, in which said polymerisation reaction yields a poly(9,10-dihydro-9,10-anthrylene vinylene) (ii, ix, xiv, xxxvi).

19. A method according to claim 18, which comprises dehydrogenating at least a proportion of said anthrylene units at their 9,10-positions.

20. A method according to Claim 19, in which said anthrylene units are dehydrogenated by heat.

21. A method according to Claim 19, in which said anthrylene units are dehydrogenated using an oxidising agent.

22. A method according to Claim 21 , in which said oxidising agent comprises 2,3-dichloro-5,6-dicyano-1 ,4-benzoquinone (DDQ).

23. Poly(9,10-dihydro-9,10-anthrylene vinylene)s and substituted derivatives thereof (ii, ix, xiv, xxxvi) synthesised by a method according to any preceding claim.

24. Poly(9,10-anthrylene vinylene)s and substituted derivatives thereof synthesised by a method according to any preceding claim.

25. Poly(9,10-dihydro-9,10-anthrylene vinylene)s and substituted derivatives thereof (ii, ix, xiv, xxxvi).

26. Homopolymeric poly(9,10-dihydro-9,10-anthrylene vinyl- ene)s and substituted derivatives thereof.(ii, ix, xiv, xxxvi).

27. Poly(2-chloro-9,10-dihydro-9,10-anthrylene)s (ix).

28. Poly(2-chloro-9,10-dihydro-9,10-anthrylene) having five anthrylene units (ix).

29. Homopolymeric Poly(9,10-dihydro-9,10-anthrylene vinyl- ene)s and sub-stituted derivatives thereof containing from 20 to 30 anthrylene units (xiv).

30. Poly(2-ethyl-9,10-dihydro-9,10-anthrylene vinylene)s (xiv).

31. Poly(2-ethyl-9,10-dihydro-9,10-anthrylene vinylene) having from 20 to 30 anthrylene units (xiv).

32. Poly(9,10-anthrylene vinylene)s and substituted derivatives thereof, in which a proportion of the anthrylene units are 9,10- -dihydrogenated (vi).

33. Poly(2-ethyl-9,10-anthrylene vinylene)s (xvii) in which a proportion of the anthrylene units are 9,10-dihydrogenated.

34. Poly(2-ethyl-9,10-anthrylene vinylene) having from 20 to 30 anthrylene units in which a proportion of the anthrylene units are 9,10- dihydrogenated (xvii).

35. Poly(9,10-anthrylene vinylene)s and substituted derivatives thereof having more than seven anthrylene units (v, xv, xxxvii).

36. Homopolymeric poly(9,10-anthrylene vinylene)s and substituted derivatives thereof (v, xv, xxxvii).

37. Homopolymeric poly(9,10-anthrylene vinylene)s and substituted derivatives thereof containing from 20 to 30 anthrylene units.

38. Poly(2-ethyl-9,10-anthrylene vinylene)s (xv).

39. Poly(2-ethyl-9,10-anthrylene vinylene) having from 20 to 30 anthrylene units (xv).

40. A method according to any preceding claim of forming copolymers characterised by copolymerisation of monomeric precursor material comprising at least two non-identically substituted dibenzobarrelene monomers (i, vii, xiii, xxxv).

41. A method according to any preceding claim of forming copolymers characterised by copolymerisation of monomeric precursor material comprising an alkene or alkenes and dibenzobarrelene or a substituted derivative or derivatives thereof (i, vii, xiii, xxxv).

42. A method according to Claim 41 in which said alkene or alkenes comprises any one or combination of: norborn-2-ene, 7-oxanorbom-2-ene, norboma-2,5-diene, 7~oxanorboma-2,5-diene, bicyclo[2.2.2]-octa-2,5-diene, barrelene (namely bicyclo[2.2.2]-octa-2,5,7- triene), or benzobarrelene (namely 1 ,4-dihydro-1 ,4-ethenonaphthalene), or substituted derivative or derivitatives thereof.

43. A method according to Claim 42 in which said barrelene or barrelenes comprises (xxix) or (xxx).

44. A method according to Claims 42 or 43 in which said benzobarrelene comprises (xxviii).

45. Copolymers, synthesised by a method according to any preceding claim, containing [9,10-dihydro-9,10-anthrylene vinylene] subunits.or derivatives thereof (ii, ix, xiv, xxxvi; n s= 1).

46. Copolymers, synthesised by a method according to any preceding claim, containing [9,10-anthrylene vinylene] subunits or derivatives thereof (v, xv, xxxvii; n s ).

47. Copolymers, synthesised by a method according to any preceding claim, containing both [9,10-dihydro-9,10-anthrylene vinylene] subunits and [9,10-anthrylene vinylene] subunits or derivatives thereof.

48. A method according to any preceding claim of forming block copolymers characterised by sequential copolymerisation of monomeric precursor material comprising at least two non-identically substituted dibenzobarrelene monomers (i, vii, xiii, xxxv).

49. A method according to any preceding claim of forming block copolymers characterised by sequential copolymerisation of monomeric precursor material comprising an alkene or alkenes and dibenzobarrelene or a substituted derivative or derivatives thereof (i, vii, xiii, xxxv).

50. A method according to Claim 49, in which said alkene or alkenes comprises any one or combination of: monocyclic alkene, norborn-2-ene, 7-oxanorborn-2-ene, norboma-2,5-diene, 7-oxanorborna-2,5-diene, bicyclo[2.2.2]-octa-2,5-diene, barrelene (namely bicyclo[2.2.2]-octa-2,5,7- triene), or benzobarrelene (namely 1 ,4-dihydro-1 ,4-ethenonaphthalene), or substituted derivative or derivitatives thereof.

51. A method according to Claim 50 in which said barrelene or barrelenes comprises (xxix) or (xxx).

52. A method according to Claims 50 or 51 in which said dibenzobarrelene comprises (xxviii).

53. Block copolymers, synthesised by a method according to any preceding claim, comprising, at least in part, a block or blocks of contiguous [9,10-dihydro-9,10-anthrylene vinylene] subunits (ii, ix, xiv, xxxvi).

54. Block copolymers, synthesised by a method according to any preceding claim, comprising, at least in part, a block or blocks of contiguous [9,10-anthrylene vinylene] subunits (v, xv, xxxvii).

55. Block copolymers, synthesised by a method according to any preceding claim, comprising, at least in part, a block or blocks of contiguous [9,10-anthrylene vinylene] subunits, wherein a proportion of the anthrylene units are 9,10-dihydrogenated (vi, xvii).