WO2010112831A1 - Liquid crystal elastomer beads - Google Patents

Abstract

There is described cross-linked polymer beads comprising one or more laterally attached mesogenic groups and methods of their preparation.

Description

Liquid Crystal Elastomer Beads

Field of the invention

The present invention relates to a novel material comprising an elastomeric cross- linked polymer network bead provided with liquid crystalline moieties on the inside. The invention further relates to methods of preparation of such novel polymeric beads and to uses thereof .

More particularly, the invention relates to cross-linked polymer beads which comprise one or more laterally attached mesogenic groups.

Background of the invention

Liquid crystals are intermediate in order between the liquid and the crystalline solid states and therefore combine fluidity with phase anisotropy. This anisotropy can be observed in many of the physical properties of a liquid crystal, such as a difference in refractive index in different directions. This phenomenon is known as optical birefringence and of great importance for applications of liquid crystals.

The combination of order, fluidity and collective behaviour of molecules is characteristic of liquid crystals and provides ordering or alignment over larger distances on surfaces. This order easily realigns in reaction to an applied electric field. In combination with the optical birefringence, this enables the use of liquid crystals in electro-optic devices and they are therefore widely known for their application in, for example, liquid crystal displays. It is understood that it is the liquid crystallinity of many biological materials that enables the amplification of the material's properties at a molecular level, for example, at cell surfaces, and therefore, the sensing of and transmission of information over larger length scales. Synthetic liquid crystals also possess the same sensing capability, but lack the inherent confinement of geometry found with cells. Furthermore, recently devised synthetic liquid crystal bio-sensors therefore need external alignment surfaces for their function.

The nematic phase is the least ordered of all the liquid crystal mesophases, exhibiting only orientational order and no positional or translational order. On average rod-like molecules show a slight preferential orientation of their molecular long axis in one direction. The local director, n is a vector parallel to this direction, which is also parallel to the optic axis of the material.

The nematic phase is the most technologically and commercially important of all the liquid crystal mesophases due to the high fluidity of the phase with maintained anisotropy. The most obvious example is the twisted nematic liquid crystal display (TNLCD).

The chiral nematic phase is similar to the nematic phase in that the molecules are directionally ordered parallel to the local director, n. However, the loss of symmetry due to the chirality of the molecules causes the director to rotate about an axis, leading to a helical formation where the same local director orientation is repeated twice every 360°. The length required for this 360° rotation is known as the pitch length and is temperature dependant. Usually the pitch is short at high temperature and increases as the temperature decreases. This is due to the high thermal energy increasing the rate at which the director, n twists. In the case of the chiral nematic phase, the optic axis is perpendicular to the director n.

In general, the direction of the pitch is dependent on the handedness of the chiral enantiomer. Although most chiral nematic phases are observed for molecules containing a chiral unit, this phase can also be produced by the addition of a small amount of a chiral material.

Cross-linked polymer network beads are polymer colloids or microspheres with dimensions from the submicron level to several hundreds of microns. They are extensively used in, e.g. medical and biological applications, as polymer supports in catalysis, for chromatographic separation and solid-phase extraction (SPE). Such cross-linked polymer network beads can be prepared using conventionally known heterogeneous polymerisation methods, e.g. by emulsion polymerisation, suspension polymerisation, dispersion polymerisation, precipitation polymerisation, etc. Such methods are known in the art, for example, from P. A. Lovell, M. S. El-Aasser (Eds), 'Emulsion Polymerization and Emulsion Polymers', Wiley, New York, 1997; R. Arshady, 'Suspension, Emulsion, and Dispersion Polymerisation: A Methodological Survey', Colloid Polym. ScL 270, 717-32 (1992); P. J. Dowding, B. Vincent, 'Suspension Polymerisation to Form Polymer Beads', Colloids and Surfaces A: Physicochem. Eng. Aspects 161, 259-69 (2000).

As hereinbefore described, cross-linked polymer beads, such as cross-linked polymer colloids or microspheres, vary in sizes from the nanometre to the micrometer, which makes them far larger than molecular entities. In fact polymer colloids can reach sizes which are comparable to red blood cells or bacteria, whilst microsphere particles can be as big as fine sand particles.

However, cross-linked polymer beads may also possess the property of being elastic and therefore, for example, can be designed by controlling the degree of cross-linking so that they are able to swell in a solvent. Thus, they can present their functionality to small reagents diffusing into the bead.

Rudolf Zentel, et al, Macromolecules, 2006, 39, 8326-8333, describes dispersion polymerisation for the conversion of liquid crystalline acrylate monomers into spherical, but optically anisotropic, colloids possessing nematic phases. However, the beads/colloids produced are not cross-linked polymer network beads and are therefore non-elastic, e.g. they are not swellable.

For example, US Patent No. 6,677,042 describes polymer beads comprising an anisotropic polymer material with helically twisted structure. However, the polymer beads described therein do not comprise laterally attached mesogenic groups and are cross-linked to achieve improved stability. Thus, the polymer beads are therefore not designed to be elastic responsive or swellable materials.

Summary of the Invention

We have now surprisingly found that the properties of liquid crystals may be combined with cross-linked polymer beads to produce novel materials. Thus, according to a first aspect of the invention we provide a novel cross-linked polymer bead comprising one or more laterally attached mesogenic groups.

It is an object of the present invention that the cross-linked polymer beads comprise elastic properties. By the term elastic used herein we mean reversibly deformable, i.e. a reversible change in shape/size of the cross-linked polymer bead and/or of the liquid crystalline order, e.g. when subjected to an external influence, such as an external reaction, temperature, mechanical influence, electrical influence, magnetic influence, solvent, etc.. Furthermore, we have found that the desirable elastic properties may be achieved when only a proportion of the polymer beads comprise a lateral mesogenic group. Thus, when measured as a proportion of the monomer units in the polymer bead, as little as 5% of the monomer units may comprise a lateral mesogenic unit, for example, less than 10% or less than 20 % or less than 40% of the monomer units may comprise a lateral mesogenic group. The remainder may be terminally attached mesogenic units. However, it is within the scope of the present invention for substantially all of the monomer units to comprise lateral mesogenic units.

It will be understood by the person skilled in the art that a variety of conventionally known polymerisable units may be used to prepare the cross-linked beads of the invention. It will also be understood by the person skilled in the art that the polymer material may comprise a homopolymer, a co-polymer, or a mixture of homopolymer or one or more co-polymers.

Thus, for example, lateral mesogenic units may be based upon structure of a compound of formula I; (R\-(X\-R²-(X²yY-(X³)_s-R³-(X\-(R\

X_n X_n X_n

formula I in which R¹ and R⁴, which may be the same or different, are each alkyl Cl to 20, alkenyl C2 to 20, alkynyl C2 to 20, haloalkyl Cl to 20, haloalkenyl C2 to 20, haloalkynyl C2 to 20, -(SiO)_a(CH₂)_v- or (-OCH₂CH₂-)_W or one of R¹ and R⁴ is -CN, - NC, -NO₂, -NCS, -SCN, -CF₃, -OCF₃; X¹ and X⁴, which may be the same or different, are each -O-, -S-, -C(O)O-, -OC(O)-, -C(O)S-, -SC(O)-, -C(O)NR⁵, -NR⁶C(O)- Or-SiR⁷R⁸;

R and R , which may be the same or different, are each cycloalkyl C3 to 12, a 3 to 12 membered heterocycloalkyl, a 6 to 14 membered aryl or a 5 to 14 membered heteroaryl, each of which may be optionally fused to an aryl and each of which may be optionally substituted by one or more substituents selected from halogen or alkyl Cl to 20, e.g. Cl to 10;

X² and X³, which may be the same or different, are each -C(O)O-, -OC(O)-, -C(O)S-, -SC(O)-, -C(S)O-, -OC(S)-, -C(S)S-, -SC(S)-, (-CH₂CH₂-)_ml, (-CH=CH-),^ (-C≡C-)^, -CH=N, -CH₂O-, -OCH₂-, -CH₂S-, -SCH₂-, -N=N-, a carborane or a tricyclic hydrocarbon, such as adamantane; and

Y is cycloalkyl C3 to 12, a 4 to 12 membered heterocycloalkyl, a 6 to 14 membered aryl or a 5 to 14 membered heteroaryl, each of which may be optionally substituted by one or more substituents selected from halogen or alkyl Cl to 20, e.g. Cl to 10; the group X_p represents the linkage to a polymerisable unit of the polymer, e.g. is - OCH₂-, -OC(O)CH₂- or -C(O)OCH₂-, or a single bond, provided that only one R², R³ and Y is provided with such a connection to the polymerisable unit; R⁵ and R⁶, which may be the same or different, are each hydrogen or alkyl Cl to 6; R⁷ and R⁸. which may be the same or different, are each alkyl Cl to 6; n, m, q, r, s and t which may be the same or different, are each 0 or 1; a, v, m¹, m² and m³, which may be the same or different, are each an integer 1 or 2; w is an integer 1, 2 or 3; and isomers thereof.

When the moieties R², R³ and Y do not carry a lateral chain linking the mesogen to the polymerisable unit X_p, each of the aforementioned moieties may comprise one or more lateral substituents selected from halogen or alkyl Cl to 20, e.g. Cl to 10 and combinations thereof.

For purposes of interpreting this specification, the following definitions will apply and whenever appropriate, terms used in the singular will also include the plural and vice versa.

The term "heterocycloalkyl" will be understood by the person skilled in the art and shall include saturated or unsaturated non-aromatic ring systems which may be monocyclic or bicyclic. A monocyclic ring system may have from 4 to 12 atoms, preferably from 4 to 7. A bicyclic ring system may have from 7 to 12 atoms, preferably 10 to 12. Such ring systems contain at least one heteroatom selected from O, N and S. The heterocyclic group can be attached at a heteroatom or a carbon atom. Examples of heterocycloalkyl groups include, but shall not be limited to, piperazine, piperidine, pyrrolidine, imidazoline, morpholine, thiomorpholine, tetrahydrofuran, dihydrofuran, etc. As used herein, the term "aryl" refers to an aromatic carbocyclic ring system containing 6 to 14 ring carbon atoms, which may be unsubstituted or substituted as defined.

The term "heteroaryl" will be understood by the person skilled in the art and shall include a 5 to 14 membered monocyclic- or bicyclic- ring system, preferably 5 to 10 membered or more preferably 5 to 7 membered, having 1, 2 or 3 heteroatoms. Such ring systems shall contain at least one heteroatom selected from O, N or S. Examples of heteroaryl groups include pyrrole, imidazole, pyrazole, thiazole, isothiazole, oxazole, isoxazole, triazole, tetrazole, pyridine, pyrazine and pyrimidine. A heteroaryl group may be mono-, bi-, tri-, or polycyclic, preferably mono-, bi-, or tricyclic, more preferably mono- or bicyclic.

The term "alkyl" shall be understood by the person skilled in the art and shall include fully saturated, branched and unbranched hydrocarbon moieties, i.e. primary, secondary or tertiary alkyl or, where appropriate, cycloalkyl or alkyl substituted by cycloalkyl, they may also be saturated or unsaturated alkyl groups. Where not otherwise identified, preferably the alkyl comprises 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, 1 to 10 carbon atoms, 1 to 7 carbon atoms, or 1 to 4 carbon atoms. Representative examples of alkyl include, but are not limited to, methyl, ethyl, «-propyl, iso-propyl, /ϊ-butyl, sec-butyl, iso-butyl, tert-butyl, «-pentyl, isopentyl, neopentyl, w-hexyl, 3-methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, ra-heptyl, n-octyl, n-nonyl, «-decyl and the like. The term "halogen" will be understood by the person skilled in the art and shall include fluoro, chloro, bromo, and iodo.

The term "haloalkyl" shall be understood by the person skilled in the art and shall include an alkyl as defined herein, that is substituted by one or more halo groups as defined herein. Preferably the haloalkyl can be monohaloalkyl, dihaloalkyl or polyhaloalkyl including perhaloalkyl. A monohaloalkyl can have one iodo, bromo, chloro or fluoro within the alkyl group. Dihaloalkyl and polyhaloalkyl groups can have two or more of the same halo atoms or a combination of different halo groups within the alkyl. Preferably, the polyhaloalkyl contains up to 12, or 10, or 8, or 6, or 4, or 3, or 2 halo groups. Non-limiting examples of haloalkyl include fluoromethyl, difluoromethyl, trifluoromethyl, chloromethyl, dichloromethyl, trichloromethyl, pentafluoroethyl, heptafluoropropyl, difluorochloromethyl, dichlorofluoromethyl, difluoroethyl, difluoropropyl, dichloroethyl and dichloropropyl. A perhaloalkyl refers to an alkyl having all hydrogen atoms replaced with halo atoms

Furthermore, it is within the scope of the present invention that the mesogenic unit may comprise a chiral moiety. When a chiral mesogenic unit is present, the chiral moiety may be present in one or both of the lateral mesogenic unit and the terminally attached mesogenic unit. In addition, when the mesogenic unit comprises a chiral mesogen any one of the groups in the mesogen, for example, as hereinbefore described in formula I, may carry the chiral centre.

The mesogens of formula I as hereinbefore described are either known per se or may be prepared using conventional methods known per se to the person skilled in the art. Alternatively, the cross-linked polymer bead may comprise a liquid crystal mesogen comprising a compound of general formula VII;

formula VII R¹, R², R³, R⁴, X¹, X², X³, X⁴, X_p, n, m, q, r, s and t are each as hereinbefore defined; and

Y^LC is cycloalkyl C3 to 12, 4 to 12 membered heterocycloalkyl, a 6 to 14 membered aryl or a 5 to 14 membered heteroaryl, each of which is substituted by a polymerisable unit, e.g. a monomer unit. However, we have found that polymerisable units based on acrylates, such as methacrylates, e.g. methyl methacrylate, and/or styrene may suitably be used.

An example of a mesogen is based upon the structure of a dibenzoyl dihydroxy benzoate, e.g. derived from formula II;

formula Il

in which R¹ and R⁴ are as hereinbefore defined.

An exemplary and known method of synthesising a lateral mesogenic unit of formula II as hereinbefore described is illustrated by the following schematic 1:

DCM

It will be understood by the person skilled in the art that compounds of formulae I and II as hereinbefore described may be prepared using methods analogous that described in schematic 1 or by other methods known per se.

In one embodiment of the present invention one of the end groups, e.g. R¹ or R⁴ may comprise a chiral centre. It will generally be required that two end groups of the lateral mesogenic unit as hereinbefore described are not the same, i.e. in the compound of formula I or II one of R¹ and R⁴ is chiral, by way of example only, compounds of formula HI;

in which R⁴ represents -C_nH_2n+^ and n is an integer from 1 to 20, e.g. 1 to 10.

An exemplary method of synthesising the chiral lateral mesogenic units as hereinbefore described is illustrated, but should not be limited by the scheme 1 :

Scheme 1

In a preferred aspect of the invention the liquid crystal mesogen will generally comprise a compound of formula IV;

wherein R¹ and R⁴ are each as hereinbefore defined; and RL_C is a polymerisable group, e.g. a monomer unit.

Certain of the liquid crystals are particularly of interest, for example those in which the moiety RLC is;

or

Thus, according to a further aspect of the invention we especially provide a novel cross-linked polymer bead comprising at least one liquid crystal which comprises the structural formula IV:

formula IV

in which R₁ and R₂, which may be the same or different are each R₁ and R₂, which may be the same or different, are each alkyl 1 to 20, e.g. Cl to 10; and RLC is;

or

The invention especially provides a novel cross-linked polymer bead comprising at least one liquid crystal of formula IV wherein one of R¹ and R⁴ is chiral.

A method of preparing a cross-linked polymer bead comprising a liquid crystal of formula IV may comprise reacting a compound of formula II;

formula Il

wherein R₁ and R₂, which may be the same or different, are each alkyl 1 to 20, e.g. Cl to 10. with a compound of formula V or VI; formula V

formula Vl

in which n is an integer from 1 to 20, e.g. 1 to 10.

In this aspect of the invention the liquid crystal monomelic unit may be synthesised by the following exemplary method:

To produce the liquid crystalline monomers, lateral substituents based on methyl methacrylate and styrene were introduced into the nematic and chiral nematic aromatic mesogenic units. Firstly, this required the synthesis of methyl methacrylate and styrene derivatives with different spacer units. Scheme 2 shows the synthesis of the 4-hydroxy butylmethacrylate (14), the 11 -hydroxy undecyloxy styrene (13). It will be understood by the person skilled in the art that the method below is an exemplary method and other compounds of formula I as hereinbefore described may be prepared using methods analogous that described in the scheme below or by other methods known per se.

Scheme 2: Synthesis of polymerisable units

Scheme 3: Synthesis of nematic and chiral nematic monomers. The polymeric beads may be prepared using methods generally known per se, for example heterogeneous polymerisation. Such heterogeneous polymerisation methods include, but shall not be limited to, emulsion polymerisation, suspension polymerisation, dispersion polymerisation and precipitation polymerisation.

Heterogeneous polymerisation techniques in general offer control over the size and size-distribution of the beads, depending, inter alia, upon the polymerisation technique and special conditions applied.

For example, dispersion polymerisation, may provide beads with sizes from about 0.1 to 50 μm. Emulsion polymerisation may provide beads with a size of from about 0.05 to 10 μm and the size distribution may be further reduced by implementing the use of "micro emulsions" which may produce beads with a size range of from about 10 to 100 nm.

Suspension polymerisation may produce polymer beads with a size distribution of from 0.1 to 5 mm.

Thus, according to a further aspect of the invention we provide a method of manufacturing a cross-linked polymer bead, e.g. an elastomer polymer bead, comprising one or more laterally attached mesogenic groups as hereinbefore described, which comprises heterogeneous polymerisation of a polymerisable monomer which monomer comprises one or more lateral mesogenic units. The method comprises the formation of a three dimensional network by performing the polymerisation in the presence of a cross-linker. In this aspect of the invention the cross-linked polymer beads comprising a core with one more attached lateral mesogenic units, e.g. a liquid crystalline core, may be synthesised by following exemplary heterogeneous suspension methods.

An aspect of the present invention is to provide nematic polymer beads from nematic monomers by heterogeneous polymerisation as hereinbefore described, e.g. suspension polymerisation. In a typical suspension polymerisation for the production of gel-type, elastomer polymer beads of the invention the liquid monomer/cross- linker/initiator mixture may be dispersed by vigorous stirring in an excess of an immiscible aqueous phase. The aqueous phase may contain a suspension stabiliser, for example, a surface active compound that may be used to increase the viscosity of the aqueous phase. Such a suspension stabiliser may be a water soluble polymer such as PVA added to the water phase to reduce droplet coalescence of the dispersed monomer mixture. Although the temperature at which a suspension polymerisation is carried out may vary, it may, for example, be carried out at temperatures of about 80 ⁰C.

In another aspect of the present invention the suspension polymerisation of the synthesised monomers may be carried out in a small scale batch reactor, especially designed to minimise regions of different shear-stress in order to prevent droplet coalescence in regions with the least shear stress and droplet break-up in regions of highest shear-stress, such as the vortex near the stirring rod. A picture of the reactor used for the suspension polymerisations is shown in Figure 2 herein. Because of the size of the reactor and the need for at least a 1:15 ratio of the dispersed monomer phase with respect to the aqueous phase, a minimum amount of 2g of monomer is generally required for each polymerisation.

More specifically, of the synthesised monomers, the styrene based nematic monomers and the nematic methacrylate monomers were used for the suspension polymerisation trials. After scale-up-reactions were carried out within the group, they were available in the necessary large quantities.

In contrast to the liquid monomers used in traditional suspension polymerisations, the nematic monomers considered here are solids at room temperature. However, they were chosen so as to be liquid or nematic at the polymerisation temperature of about 80⁰C.

In a typical experiment the solid mixture of 2g monomer, 1 mol% cross-linker and 3 mol% initiator azobiscyclohexylcarbonitrile (ABCN), was added to 30 mL of a preheated solution of 1.6w% polyvinyl alcohol) (PVA) in water and the mixture was stirred at high speed until the monomer was melted and a smooth suspension of opaque appearance was observed, as shown in figure 1. The stirring rate was at that point (usually after a few minutes) reduced to the rpm stated in Table 3.

The change in appearance during the polymerisation process indicated that the continuous water phase was not able to stabilise the monomer droplets throughout the whole polymerisation process, with the most important factors being the increase in viscosity of the monomer phase during polymerisation and the polarity of the monomers.

Modified conditions introduced an increase in the concentration of PVA in the water phase to increase the drop stabilisation and prevent droplet coalescence, and an increase in the amount of cross-linker in order to obtain cross-linked particles at an earlier stage in the polymerisation. Furthermore, the monomer may be dissolved in a minimal amount of toluene in order to reduce the viscosity and polarity of the dispersed monomer phase.

To remove the PVA, the polymer beads may be cleaned by a series of repeated processes which comprise stirring in water, settling and decanting. The polymer beads were collected by filtration and unreacted monomer was removed via a soxhlet extraction with dichloromethane. Finally, the polymer beads may be dried in a vacuum. The polymer beads can be analysed for their size and size distribution. Optical and thermal optical properties can be determined by microscopy, Polarised Optical Microscopy (POM) and/or Differential Scanning Calorimetry (DSC). Structural characterisation may be carried out by IR. The average size and size distribution of the microspheres may be determined from microscopy pictures by measuring the size of about 30 polymer beads in each case.

As can be seen in Table 3, the average size of polymer beads MS20, MS21, MS24 and MS18a, synthesised under the initial conditions are (with the exception of MS20) of comparable magnitude, and fall between 390-460 μm. The improvement of the reaction conditions is also reflected in a size reduction of the resulting microspheres for the experiment MS18b, yielding polymer beads with an average diameter of around 190 μm.

When examined by POM under crossed polarisers, all polymer beads synthesised from the nematic monomers proved to be birefringent at room temperature. On heating above the T_g, the textural appearance generally improved and the spheres developed the typical birefringence colours and defect textures of the nematic phase. This behaviour above and below T_g is shown in Figure 3 for the microspheres MS18b.

On annealing well above T_g, the polymer beads were also able to develop single monodomains within the spheres, as shown in Figure 4 for microspheres MS21 and MS 18b.

According to a further aspect of the invention we provide a cross-linked polymer bead as hereinbefore described wherein the surface, i.e. the outer surface of the bead, is derivatised.

Thus, for example, the surface functionalisation of the bead may be achieved by employing known methods to provide reactive groups at the surface of the polymer bead. An exemplary method may comprise the introduction of a small amount of a reactive co-monomer into the polymer network forming process. This may be advantageous in that the reactive group at the surface of the bead can subsequently be used to modify the surface functionality of the bead as desired. The liquid crystalline elastomer polymer beads as hereinbefore described may have a wide variety of utilities. However, the liquid crystalline elastomer polymer beads are useful as, inter alia, optical sensors. They are able to function as sensors because the elasticity, in combination with the liquid crystallinity, provides them with the ability to reversibly respond with a change in shape/size of the cross-linked polymer bead and/or of the liquid crystalline order to an external influence such as, for example, an external reaction, temperature, mechanical influence, electrical influence, magnetic influence, or solvent, etc. Therefore, in one aspect of the invention we provide a sensor comprising an elastomer cross-linked polymer bead comprising a liquid crystalline core.

Experiments show the beads to be able to respond to the application of a small mechanical force with an elastic shape deformation resulting in a change in colour (retardation). The response is fast and reversible as shown in Figure 5. The single picture on top shows the initial (frame 1) and final (frame 8) appearance of the bead before and after the pressure was applied. On applying and increase of the mechanical force the bead responds with a successive colour change which reverses back to the original appearance on release of the external force.

The beads are therefore able to function as optical sensors for the detection of external mechanical forces. They show a fast, elastic, reversible optical response to an externally applied mechanical stimulus.

The invention also provides the use of a liquid crystal as hereinbefore described in the manufacture of a cross-linked polymer bead comprising a liquid crystalline core. In the lateral side-chain LC polymers considered here, the differing spacer length and the different length of the terminal alkoxy groups in the mesogenic unit, each increase the flexibility within the whole polymer molecule with increasing length.

Detailed Description of the Invention

The invention will now be described by way of example only and with reference to the accompanying figures in which Figure 1 is a schematic representation of a side chain lateral liquid crystal polymer; Figure 2 is a photograph of suspension polymerisation in progress;

Figure 3 is polarised optical photomicrographs of MS18b (a) below Tg at room temperature and (b) above Tg at 66 ⁰C;

Figure 4 is a polarised optical micrograph of (a) MS21 at 98°C (x50) and (b) MS18b at 77°C (xlOO); and Figure 5 is consecutive frames of a polarising optical microscopy video taken whilst mechanical deformation of a bead of MS 18b at 57°C in silicon oil.

Abbreviations

ABCN Azobiscyclohexylcarbonitrile AIBN Azobisisobutylcarbonitrile

DCC N, N'-Dicyclohexylcarbodiimide

DCM Dichloromethane

DEAD Diethyl diazenedicarboxylate

DMAP 4-Dimethylaminopyridine DMF Dimethylformamide DNA Deoxyribonucleic acid

DP Degree of polymerisation

DSC Differential scanning calorimetry

EDAC l-Ethyl-3-(3-dimethylaminopropyl)carbodiimide

GPC Gel permeation chromatography

IR Infrared spectroscopy

MCLCP Main-chain liquid crystal polymer

M_n Number average molecular weight

M_w Weight average molecular weight

N Nematic

N* Chiral nematic

NMR Nuclear magnetic resonance

PD Polydispersity

POM Polarised optical microscopy

PVA Poly( vinyl alcohol)

SCLCP Side-chain liquid crystal polymer

Tg Glass transition temperature

THF Tetrahydrofuran

TNLCD Twisted nematic liquid crystal display

TPP Triphenylphosphine

IH NMR was carried out on a JEOL EX400 NMR Spectrometer at 400MHz and δ_H values are recorded in ppm. Infra red spectra were recorded using a Shimadzu IR Prestige-21 FT IR Spectrometer. Polarised optical microscopy was performed using a Zeiss AXIOSKOP 400 polarised light microscope and a Meτtler Toledo FP82HT hot stage. Differential scanning calorimetry was performed to obtain thermal transition data using a Mettler Toledo DSC 822e, calibrated to Indium at onset 156+0.2°C, ΔH 28.45+0.4 Jg^"1 . This was used in conjunction with STARe data and analysis software. Reagents and solvent which were commercially available we all used with no further purification. Column chromatography was carried out using silica gel (35-70μm) purchased from Fluka Ltd.

1. Monomer Synthesis

1.1 Benzyl-2,5-dihydroxybenzoate (1) NaHCO₃ (9.9g, 117 mmol) was added to a solution of 2,5-dihydroxybenzoic acid (6.16g, 40 mmol) in DMF (16OmL) and stirred for one hour at 70 ⁰C. After addition of benzyl bromide (6.84g, 40 mmol), the temperature was reduced to 50 ⁰C and the solution stirred overnight. The mixture was cooled, diluted with 200 niL water and extracted with 100 mL 50:50 hexane/ethyl acetate mixture (2x). The organic layer was washed with water (2x), dried over Na₂SO₄ and the solvent evaporated under vacuum, producing a white powder (8.7Og, 90%); δ_H (CDCl₃, 400MHz, 25°C) 5.35 (2H, s), 6.89 (IH, d, J 8.9), 7.00 (IH, dd, J 3.0, 8.9), 7.31 (IH, d, J 3.0), 7.40 (5H, m), 10.33 (IH, s).

1.2 Benzyl-2,5-di(4-butoxybenzoyloxy)benzoate (2)

A solution of 2,5-dihydroxybenzoate (8.73g, 35.8 mmol), 4-butoxybenzoic acid (15.28g, 78.6 mmol), EDAC (15.07g, 78.6 mmol), DMAP (1.92g, 20 mol%) in 600 mL dichloromethane was stirred at room temperature for 12 hours. The reaction mixture was washed with water (3x), dried over MgSO₄ and the solvent removed under vacuum. The white solid was then recrystallised from ethanol. (21.4g, 100%); mp 106°C; δ_H (CDCl₃, 400MHz₅ 25⁰C) 0.99 (6H₅ m), 1.23 (8H, m), 3.70 (4H₅ qu, J 6.7), 5.17 (2H, s), 6.90 (2H₅ d, J 9.2), 6.96 (2H₅ d₅ J 9.2), 7.21 (5H₅ m), 7.25 (IH₅ d, J 8.5), 7.45 (IH₅ dd₅ J 3.0, 8.9), 7.89 (IH, d₅ 3.0), 8.06 (2H₅ d₅ J 8.9), 8.12 (2H₅ d₅ J 8.9).

1.3 Benzyl-2,5-di(4-heptyloxybenzoyloxy)benzoate (3)

A solution of 2,5-dihydroxybenzoate (1.45g₅ 5.93 mmol), 4-heptyloxybenzic acid (2.8Og₅ 11.86 mmol), EDAC (2.27g, 11.86 mmol), DMAP (0.30g, 20 mol%) in 50 mL dichloromethane was stirred at room temperature for 17 hours. The reaction mixture was washed with water and brine (3x), dried over Na₂SO₄ and the solvent removed under vacuum. The product was then recrystallised from ethanol and dried in a desiccator giving a white fluffy powder (3.44g, 85.3%); mρlO6°C; δ_H (DCM₅ 400MHz₅ 25°C) 0.89 (6H₅ X, J 6.9), 1.1-1.5 (16H, m), 1.82 (4H₅ m), 4.03 (4H₅ t, J 5.6), 5.18 (2H₅ s), 6.90 (2H₅ d, J, 8.9), 6.96 (2H, d, J 9.2), 7.2 (6H₅ m), 7.45 (IH₅ dd, J 2.9, 8.85), 7.89 (IH, d₅ J 2.8), 8.06 (2H₅ d₅ J 9.2), 8.12 (2H, d₅ J 8.9) .

1.4 2,5-Di(4-butoxybenzoyloxy)benzoic acid (4)

To a solution of 2₅5-di(4-butoxybenzolyoxy)benzoate (21.4g, 35.8 mmol) in 20OmL THF and 3OmL ethanol a spatula tip of Pd on carbon (10 %w) was added. The stirred suspension was degassed 3 times and left under a hydrogen atmosphere overnight at room temperature. The reaction mixture was filtered over celite and the solvent removed under vacuum, yielding a white solid. (15.23g, 84%); mp 165⁰C; δ_H (CDCI₃, 400MHz, 25°C) 0.97 (6H, m), 1.51 (4H₃ m), 1.79 (4H₅ m), 4.02 (4H, m), 6.95 (4H, t, J 8.2), 7.27 (IH₅ d, J 8.9), 7.48 (IH, dd, J 2.9, 8.9), 7.92 (IH₅ d₅ J 2.9), 8.11 (4H, dd, J 1.8, 8.9). 1.5 2,5-Di(4-heptyloxybenzoyloxy)benzoic acid (5)

To a solution of 2,5-di(4-heptyloxybenzolyoxy)benzoate (3.4 Ig, 5.0 mmol) in 20OmL THF and 3OmL ethanol a spatula tip of Pd on carbon (10 %w) was added. The stirred suspension was degassed 3 times and left under a hydrogen atmosphere overnight at room temperature. The reaction mixture was filtered over celite and the solvent removed under vacuum, and the white solid recrystallised twice from ethanol, washed with hexane and dried in a desiccator. (0.8g, 27%); δ_H (CDCl₃, 400MHz, 25°C) 0.82 (6H, m), 1.1-1.7 (2OH, m), 3.98 (4H, t, 6.7), 6.91 (4H, d, J 8.4), 7.23 (IH, d, J 8.85), 7.44 (IH, dd, J 2.75, 8.85), 7.83 (IH, d, J 2,75), 8.06 (4H, d, J 8.85).

1.6 (R)-Benzyl-4-(l-methyl heptyloxy)benzoate (6)

To a nitrogen flushed flask containing benzyl-4-hydroxybenzoate (4.11g, 14 mmol), triphenyl phosphine (4.72g, 1.25 mol%) and dry THF (265mL) was added (S)-2- octanol (2.5 mL, 14 mmol) dissolved in 35 mL THF. After dropwise addition of ADDP (4.5g, 1.25 mol%) in 70 mL THF the mixture was stirred for 22 hours. The solvent was removed under vacuum, the remainder re-dissolved in dichloromethane and shaken well with H₂O₂ in water (10%). The organic phase was washed with (NH4.)₂Fe(SO₄)₂ and tested for peroxides before drying over MgSO₄ and the solvent removed under vacuum. The product was purified by column chromatography in 5:1 hexane/ethyl acetate mixture. (1.83g, 39%); δ_H (CDCl₃₅ 400MHz, 25°C) 0.78 (3H, t, J 6.9), 1.1-1.6 (13H, m), 4.33 (IH₃ sext, J 6.1), 5.24 (2H, s), 6.78 (2H, d, J 8.85), 7.2-7.3 (5H, m), 7.92 (2H, d, J 8.85). 1.7 (jR)-(l-Methyl heptyloxy) benzoic acid (7)

To a solution of benzyl-4-(l -methyl heptyloxy)benzoate (1.83g, 5.4 mmol) in 20OmL THF and 3OmL ethanol a spatula tip of Pd on carbon (10 %w) was added. The stirred suspension was degassed 3 times and left under a hydrogen atmosphere overnight at room temperature. The reaction mixture was filtered over celite and the solvent removed under vacuum, yielding a colourless oil (1.3 Ig, 97%); δπ (CDCl₃, 400MHz, 25°C) 0.80 (3H₅ 1, J 6.9) 1.16-1.68 (13H₅ m) 4.39 (IH₅ sext, J 6.1) 6.83 (2H₅ d, J 8.5) 7.96 (2H, d₅ J 8.5).

1.8 (JR)-Benzyl-2-(hydroxy)-5-((l-methyl heptyloxy) benzoyloxy)benzoate (8)

A solution of 2,5-dihydroxybenzoate (3.9Og, 3 eq.), (R)-(l-methyl heptyloxy) benzoic acid (1.3Ig₅ 5.26 mrnol), EDAC (1.0Og₅ 5.26 mmol), DMAP (0.13g, 20 mol%) in 100 niL Dichloromethane was stirred overnight at room temperature, washed with water (3x), dried over Na₂SO₄ and the solvent removed under vacuum. The product was purified by column chromatography in 10:1 hexane/ethyl acetate mixture to yield a yellow oil (1.4g, 55.9%); δ_H (CDCl₃, 400MHz, 25⁰C) 0.86 (3H, t, J 6.9) 1.30 (1OH, m), 1.53 (3H₅ s), 4.45 (IH₅ sext, J 6.1), 5.35 (2H, s), 6.91 (d₅ J 8.8), 7.00 (IH, d, J 8.8), 7.28 (IH₅ dd, J 2.9. 6.1), 7.34-7.42 (5H, m), 7.65 (IH, d₅ J 2.9)₅ 8.07 (2H, d, J 9.2).

1.9 (Λ)-Benzyl-2-(4-butoxybenzoyloxy)-5-(4-(l-methylheptyloxy))benzoyloxy) benzoate (9)

A solution of (R)-benzyl-5-((l -methyl heptyloxy) benzoyloxy)benzoate (1.4g₅ 2.94 mmol), 4-butoxybenzoic acid (0.57g, 2.94 mmol), EDAC (0.56g, 2.94 mmol), DMAP (0.07g, 20 mol%) in 40 mL dichloromethane was stirred at room temperature for three days. The mixture was washed with water (3x), dried over Na₂SO₄ and the solvent removed under vacuum. The product was then recrystallised from ethanol yielding a white powder (1.83g, 95.5%); mp 92°C; δ_H (CDCl₃, 400MHz, 25°C) 0.88 (3H, t, J 6.9), 1.00 (3H₃ t, J 7.5), 1.2-1.6 (14H, m), 1.81 (3H, m), 4.04 (2H₃ 1, J 6.4), 4.48 (IH, sext, J 6.1), 5.18 (2H, s), 6.91 (2H, d, J 8.9), 6.94 (2H, d, J 8.9), 7.2 (6H, m), 7.44 (IH, dd, J 2.9, 8.5), 7.88 (IH, d, J 3.0), 8.06 (2H, d, J 8.9), 8.11 (2H, d, J 8.9).

1.10 (Λ)-Benzyl-2-(4-heptyloxybenzoyloxy)-5-(4-(l-methylheptyloxy)) benzoyloxy) benzoate (10) A solution of (R)-benzyl-5-((l-methyl heptyloxy) benzoyloxy)benzoate (5.0Og₃ 10.5 mmol), 4-heptyloxybenzoic acid (2.48g, 10.5 mmol), EDAC (2.01g, 10.5 mmol), DMAP (0.26g, 20 mol%) in 300 mL dichloromethane was stirred at room temperature for three days. The solvent removed under vacuum and the crude residue purified by column chromatography (hexane/ethyl acetate 4:1), yielding a white powder (4.83g, 66 %); δ_H (CDCl₃, 400MHz, 25°C) 0.88 - 1.00 (m, 6H), 1.2-1.6 (20 H, m), 1.81 (3H, m), 4.04 (2H, t, J 6.4), 4.48 (IH, sext, J 6.1), 5.18 (2H₃ s), 6.91 (2H, d₃ J 8.9), 6.94 (2H, d, J 8.9), 7.2 (6H, m), 7.44 (IH₃ dd, J 3.0, 8.5), 7.88 (IH, d, J 3.0), 8.06 (2H, d, J 8.9), 8.11 (2H, d, J 8.9).

1.11 (i?)-2-(4-butoxybenzoyloxy)-5-(4-(l-methyl heptyloxy))benzoyloxy)benzoic acid (11)

To a solution of (R)-benzyl-2-(4-butoxybenzoxy)-5-(4-(l-methyl heptyloxy)) benzoyloxy) benzoate (1.41g, 2.2 mmol) in 20OmL THF and 3OmL ethanol a spatula tip of Pd on carbon (10 %w) was added. The stirred suspension was degassed 3 times and left under a hydrogen atmosphere overnight at room temperature. The reaction mixture was filtered over celite and the solvent removed under vacuum. Purification was carried out by recrystallisation from ethanol followed by column chromatography in ethyl acetate, yielding a white solid (0.39g, 32%); δ_H (DCM, 400MHz, 25⁰C) 0.80 (3H, t, J 7.O)₃ 0.91 (3H, t, J 7.5), 1.1-1.5 (14H₅ m), 1.70 (3H, m), 3.98 (2H, t, J 6.4), 4.42 (IH, sext, J 6.1), 6.90 (4H, dd, J 2.3, 8.85), 7.22 (IH, d, 8.5), 7.43 (IH, dd, 2.9, 8.85), 7.82 (IH, d, 3.05), 8.04 (4H, dd, 3.7, 8.85).

1.12 (jR)-2-(4-heptyloxybenzoyIoxy)-5-(4-(l-methylheptyloxy))benzoyloxy) benzoic acid (12) To a solution of (R)-benzyl-2-(4-hepryloxybenzoxy)-5-(4-(l -methyl heptyloxy)) benzoyloxy) benzoate (1.6 Ig, 2.3 mmol) in 10OmL DCM a spatula tip of Pd on carbon (10 %w) was added. The stirred suspension was degassed 3 times and left under a hydrogen atmosphere overnight at room temperature. The reaction mixture was filtered over celite and the solvent removed under vacuum. Purification was carried out by recrystallisation from ethanol yielding a white solid (1.38g, 99%); δ_H (DCM, 400MHz, 25°C) 0.80 - 0.91 (6H, m), 1.1-1.5 (2OH, m), 1.70 (3H, m), 4.02 (2H, t, J 6.4), 4.46 (IH, sext, J 6.1), 6.92 (4H, dd, J 2.3, 8.85), 7.25 (IH, d, 8.5), 7.44 (IH, dd, 2.9, 8.85), 7.87 (IH, d, 3.05), 8.10 (4H, dd, 3.7, 8.85).

1.13 4-(ll-Hydroxyundecyloxy)styrene (13)

Acetoxystyrene (3.55g, 21.9 mmol) was added to a solution of KOH (3.55g, 63.6 mmol) in ethanol (3OmL) and stirred at room temperature for one hour. After addition of NaOEt (1.62g, 23.9 mmol) the mixture was heated and allowed to reflux for Vi hour. A solution of 11-bromo-l-undecanol (5.42g, 21.9 mmol) in ethanol (30 mL) was added and the mixture refluxed for 20 hours. The solvent was then removed under vacuum, the remaining solid dissolved in 60 mL aq. NaHCO₃ (10% w/w) and extracted with 10 mL dichloromethane (3x). The organic layer was then washed with 40 mL NaOH (IM) (2x) and again with water (60 mL), dried over MgSO₄ and the solvent removed under vacuum. Recrystallisation from hexane yielded a white powder (1.6g, 25%); mp 103°C; δ_H (CDCl₃, 400MHz, 25⁰C) 1.1-1.6 (16H, m), 1.75 (2H₅ quin, J 7.1), 3.62 (2H, t, 6.2), 3.93 (2H, t, J 6.6), 5.09 (IH, dd, J 0.9, 11.0 ), 5.58 (IH, dd, J 0.9, 17.7), 6.63 (IH, dd, J 10.8, 17.4), 6.82 (2H, d, J 8.9), 7.31 (2H, d, J 8.5).

1.14 4-Hydroxybutyl methacrylate (14)

Methacrylic acid (1.61 mL, 18.96mmol) was added dropwise to a solution of dihydroxybutane (5.13g, 3 eq.), EDAC (3.63g, 18.96 mmol), DMAP (0.46g, 20 mol%) in dichloromethane (80 mL). The mixture was stirred overnight at room temperature before removing the solvent under vacuum and purifying by column chromatography in 1:1 hexane/ethyl acetate mixture to yield a colourless oil (1.8 Ig, 60%); δ_H (CDCl₃, 400MHz, 25°C) 1.6-1.8 (4H, m), 1.92 (3H, s), 3.67 (2H, t, J 6.3), 4.16 (2H, t, 6.4), 5.53 (IH, s), 6.07 (IH, s).

1.15 11-HydroxyundecyI methacrylate (15) Methacrylic acid (16.3 Ig, 189.5 mmol,) was added dropwise to potassium hydrogen carbonate (14.83g, 148.1 mmol) and the mixture stirred for ten minutes. To this mixture bromoundecanol (8.0Og, 31.8 mmol) in DMF (120 ml) and a trace amount of hydroquinone was added and the mixture stirred at 12O⁰C for 24 hours. After cooling to room temperature, the mixture was poured onto ice-cold water , the mixture extracted with chloroform (x3), and the combined organic extracts washed with 5 % aq. sodium hydroxide solution, and then twice with water. The organic layer was then dried over magnesium sulphate, the solvent evaporated and the residue purified by column chromatography (hexane/ethyl acetate, 2:1) to yield a colourless, viscous liquid (5.23g, 64 %); δ_H (CDCl₃, 400MHz, 25°C) 1.22-1.34 (14H, m), 1.5-1.8 (4H, m), 1.92 (3H, s), 3.63-3.67 (2H, m), 4.11 (2H, t, 6.4), 5.52 (IH, m), 6.07 (IH, m).

1.16 (4-Methacryloyloxyundecyl) 2,5-di(4-heptyloxybenzoyloxy)benzoate (18)

A solution of 2,5-di(4-heptyloxybenzoylyloxy)benzoic acid (8.00g, 13.87 mmol), 4- hydroxyundecyl methacrylate (3.56g, 13.87 mmol), EDAC (3.19g, 16.6 mmol), DMAP (0.34g, 20 mol%) in 200 mL dichloromethane was stirred for three days at room temperature. The solvent was evaporated and the residue purified by column chromatography in DCM to give a white solid (8.35g, 74%); δ_H (CDCl₃, 400MHz, 25°C) 0.90 (6H, t, J 6.7), 1.10 - 1.35 (30H, m), 1.55-1.75 (2H, m), 1.80-1.85 (4H, m), 1.93 (3H, m), 4.02-4.06 (4H, m), 4.10-4.16 (4H, m), 5.53-5.57 (IH, m), 6.06-6.10 (IH, m), 6.97 (4H, dd, J 1.8, 8.9), 7.25 (IH, d, J 8.9), 7.45 (IH, dd, J 3.0, 8.9), 7.88 (IH, d, J 3.0), 8.06-8.18 (4H, m).

1.17 (4-Acryloyloxybutyl) 2,5-di(4-butoxybenzoyloxy)benzoate (19)

A solution of 2,5-di(4-butoxybenzoyloxy)benzoic acid (Ig, 1.97 mmol), 4- hydroxybutyl acrylate (0.31g, 2.17 mmol), DCC (0.45g, 2.17 mmol), DMAP (0.051g,

20 mol%) in 3OmL dichloromethane was stirred overnight at room temperature. The mixture was then washed with water, acetic acid (5%) and water, and then filtered.

The organic layer was then dried over Na₂SO₄, the solvent removed under vacuum and recrystallised from ethanol (3x) producing a white powder which was dried in a desiccator over night. (0.25g, 20%); Thermal transitions ⁰C, K 60.1 N 76.3 I; (Elemental Analysis for C₃₆H₄₀O₁₀: C, 68.34; H, 6.37; O, 25.29, Found: C, 68.49, H₅ 6.31) δ_H (CDCl₃, 400MHz, 25°C) 0.98 (6H, t, J7.3 ) 1.52 (8H₃ m) 1.80 (4H, quin, J 6.7) 4.03 (6H, m) 4.19 (2H, t, J 6.1) 5.78 (IH, dd, J 1.4, 10.6) 6.06 (IH, dd, J 10.6, 17.4) 6.35 (IH, dd, J 1.4, 17.4) 6.97 (4H, m) 7.26(1H coupling hidden by CHCl₃ signal) 7.45 (IH, dd, J 2.9, 8.9) 7.87 (IH, d, J 2.3) 8.14 (4H, m); m/z (APCI) 655 (M⁺ + Na⁺); FTIRV_ma_x Cm^"1; 2941, 2875, 1723, 1607, 1513, 1251, 1165, 1065, 1008, 845).

1.18 (4-Methacryloyloxybutyl) 2,5-di(4-butoxybenzoyloxy)benzoate (20)

A solution of 2,5-(butoxybenzoyloxy)benzoic acid (1.33g, 2.63 mmol), 4- hydroxybutyl methacrylate (0.42g, 2.63 mmol), EDAC (0.54g 2.63 mmol) and DMAP

(0.06g, 20 mol%) in dichloromethane was stirred at room temperature for three days.

The mixture was washed with water (3x), dried over Na₂SO₄, and the solvent removed under vacuum. The remaining solid was recrystallised from ethanol, followed by a recrystallisation from n-propanol to yield a white powder (0.37g, 21.8%); Thermal transitions ⁰C, K 67.4 N 74.8 1; (Elemental Analysis for C₃₇H₄₂O₁₀: C, 68.71; H, 6.55;

O, 24.74, Found: C, 69.03, H, 6.51); δ_H (CDCl₃, 400MHz, 25°C) 0.92 (6H, t, J 7.5),

1.58 (12H, m), 1.85 (3H, m), 3.96 (6H, m), 4.13 (2H, t, J 6.3), 5.45 (IH, quin, J 1.5),

5.98 (IH, m), 6.90 (4H, m), 7.18 (IH, d, 8.9), 7.37 (IH, dd, J 2.8, 8.9), 7.81 (IH, d,

2.8), 8.07 (4H, m); m/z (APCI) 669 (M⁺ + Na⁺); FTIRVm_3x cm^'1; 2961, 1730, 1607, 1512, 1420, 1250, 1161, 1060, 845.

1.19 (4-Methacryloyloxybutyl) 2,5-di(4-heptyIoxybenzoyIoxy)benzoate (21)

A solution of 2,5-di(4-heptyloxybenzoylyloxy)benzoic acid (0.37g, 0.627 mmol), 4- hydroxybutyl methacrylate (O. lOg, 0.627 mmol), EDAC (0.12g, 0.627 mmol), DMAP (0.015g, 20 mol%) in 10 mL dichloromethane was stirred overnight at room temperature. The reaction mixture was purified by column chromatography in DCM to give a white solid (0.24g, 52%); Thermal transitions ⁰C, K 49.5 N 59.9 I; (Elemental Analysis for C₄₃H₅₄Oj₀: C, 70.66; H₃ 7.45; O, 21.89, Found: C, 70.78, H, 7.53); δ_H (CDCl₃, 400MHz, 25⁰C) 0.83 (6H, t, J 6.7), 1.17 - 1.87 (27H, m), 3.91-3.99 (6H, m), 4.13 (2H, t, J 6.3), 5.45 (IH, quin, J 1.5), 5.98 (IH, q, J 0.8), 6.89 (4H, dd, J 1.8, 8.9), 7.18 (IH, d, J 8.9), 7.38 (IH, dd, J 3.0, 8.9), 7.81 (IH, d, J 3.0), 8.02-8.10 (4H, m); m/z (APCI) 753 (M⁺ + Na⁺); FTIR V_1113x cm^"1; 2927, 1731, 1606, 1511, 1244, 1161, 1066, 844.

1.20 (R)-(4-Methacryloyloxybutyl)-2-(4-butyloxybenzoyloxy)-5-(4-(l-methyl heptyloxy)) benzoyloxy)benzoate (22)

A solution of (R)-2-(4-butoxybenzoxy)-5-(4-(l-methyl heptyloxy))benzyloxy)benzoic acid (0.4g, 0.71 mmol), 4-hydroxybutyl methacrylate (0.1 Ig, 0.71 mmol), EDAC (0.14g, 0.71 mmol), DMAP (0.09g, 20mol%) in 30 mL dichloromethane was stirred for two days at room temperature. The reaction mixture was purified by column chromatography in 1:1 hexane/ethyl acetate mixture to give a white solid (0.47g, 94%); Thermal transitions ⁰C, K 54.3 N* (-13.2) I; (Elemental Analysis for C₄₁H₅₀O₁₀: C, 70.07; H, 7.17; O, 22.76, Found: C, 69.94, H, 7.24); δ_H (CDCl₃, 400MHz, 25°C) 0.81 (3H, t, J 6.9), 0.92 (3H, t, J 7.3), 1.20-1.58 (16H, m), 1.67-1.78 (3H, m), 1.84 (3H, t, J 1.2), 3.94 (2H, t, J 6.1), 3.98 (2H, t, J 6.6), 4.14 (2H, t, J 6.3), 4.42 (IH, sext, J6.1), 5.46 (IH, quin, J 1.5), 5.99 (IH, m), 6.89 (4H, m), 7.19 (IH, d, J 8.5), 7.38 (IH, dd, J 3.0, 8.9), 7.81 (IH, d, J 3.0), 8.07 (4H, m); m/z (APCI) 725 (M⁺ + Na⁺); FTIRv^ cm^"1; 2927, 1735, 1604, 1510, 1422, 1244, 1159, 1055, 837. 1.21 (i?)-(4-MethacryloyIoxybutyI)-2-(4-heptyloxybenzoyloxy)-5-(4-(l-methyl heptyloxy)) benzoyloxy)benzoate benzoate (23)

A solution of (R)-2-(4-heptyloxybenzoyloxy)-5-(4-(l -methyl heptyloxy))benzoyl oxy)benzoic acid (0.4g, 0.66 mmol), 4-hydroxybutyl methacrylate (O.lOg, 0.66 mmol), EDAC (0.13g, 0.66 mmol), DMAP (0.08g, 20 mol%) in 30 mL dichloromethane was stirred for one week at room temperature. The reaction mixture was purified by column chromatography in 1:1 hexane/ethyl acetate mixture to give a white solid (61.7g, 62%); Thermal transitions ⁰C, K 31.6 N* (-4.5) I; (Elemental Analysis for C₄₄H₅₆O₁₀: C, 70.94; H, 7.57; O, 21.48, Found: C, 70.43, H, 7.56); δ_H (CDCl₃, 400MHz, 25°C) 0.88 (3H, t, J 7.0), 0.89 (3H, t, J 6.7), 1.23-2.04 ( 27H,m), 4.12 (4H, t, J 7.0), 4.20 (2H, t, J 6.6), 4.47 (IH, sext, J 6.1), 5.52 (IH, t, J 1.5), 6.05 (IH, s), 6.94 (2H, d, J 6.4), 6.97 (2H, d, J 6.4), 7.25 (IH, d, J 8.9), 7.45 (IH, dd, J 3.0, 8.9), 7.87 (IH, d, J 3.0), 8.13 (2H, d, J 8.2), 8.15 (2H, d, J 8.5); m/z (APCI) 767 (M⁺ + Na⁴); FlTR V_n13x cm^"1; 2918, 1718, 1605, 1507, 1420, 1245, 1160, 1059, 841.

1.22 ll-(4-Vinylphenoxy)undecyloxy 2,5-di(4-butoxybenzoyloxy)benzoate (24) A solution of 2,5-di(4-butoxybenzoyloxy)benzoic acid (Ig, 1.97 mmol), 4-( 11- hydroxyundecyloxy)styrene (0.63g, 2.17 mmol), EDAC (0.42g, 2.17 mmol), DMAP (0.05g, 20 mol%) in 30 mL dichloromethane was stirred overnight at room temperature. The reaction mixture was washed with water (3x), dried over Na₂SO₄, the solvent removed under vacuum. He remaining solid was recrystallised from ethanol (3x) to give a white solid (0.16g, 10.2%); Thermal transitions ⁰C, K 74.2 N 94.9 I; (Elemental Analysis for C₄₈H₅₈O₉: C, 74.01; H, 7.50; O, 18.49, Found: C, 73.96, H, 7.48); δ_H (CDCl₃, 400MHz, 25°C) 0.99 (6H, t, 7.3), 1.1-1.8 (26H, m), 3.93, (2H, t, J 6.6), 4.05 (4H, t, J 6.6), 4.14 (2H, t, 6.7), 5.10 (IH, d, J 10.7), 5.59 (IH, d, J 17.4), 6.65 (IH, dd, J 11.0, 17.4), 6.83 (2H, d, J 8.85), 6.97 (4H, m), 7.32 (2H, d, J 8.85), 7.44 (IH, dd, J 2.9, 8.85), 7.88 (IH, d, J 2.8), 8.15 (4H, m); m/z (APCI) 801 (M⁺ + Na⁺); FTlR v_max cm^"1; 1727, 1604, 1510, 1424, 1246, 1160, 1055, 835.

1.23 ll-(4-Vinylphenoxy)undecyloxy 2,5-di(4-heptyloxybenzoyloxy) benzoate (25)

A solution of 2,5-di(4-heptyloxybenzoyloxy)benzoic acid (0.39g, 0.661 mmol), 4-(ll- hydroxyundecyloxy)styrene (0.19g, 0.661 mmol), , EDAC (0.127g 0.661 mmol), DMAP (0.016g, 20 mol%) in 10 mL dichloromethane was stirred overnight at room temperature. The reaction mixture was purified by column chromatography in 5:1 DCM/hexane mixture to give a white solid (0.37g, 65%); Thermal transitions ⁰C, K 72.9 N 84.7 I; (Elemental Analysis for C₅₄H₇₀O₉: C, 75.14; H, 8.17; O, 16.68, Found: C, 74.58, H, 8.17); δ_H (CDCl₃, 400MHz, 25°C) 0.82 (6H, t, J 6.9), 1.24 (32H, m), 1.71 (6H, m), 3.85 (2H, t, J 6.6), 3.95 (4H, t, 6.4), 4.07 (2H, t, J 6.7), 5.02 (IH, dd, J 0.9, 11.0), 5.51 (IH, dd, J 0.9, 17.7), 6.57 (IH, dd, J 10.8, 17.5), 6.76 (2H, d, J 8.9), 6.89 (4H, d, J 8.2), 7.17 (IH, d, J 8.9), 7.24 (2H, d, J 8.5), 7.37 (IH, dd, J 2.9, 8.8.7), 7.81 (IH, d, J 3.0), 8.07 (4H, m); m/z (APCI) 885 (M⁺ + Na⁺); FTIR V_n^_x cm^"1; 2915, 1734, 1604, 1507, 1420, 1243, 1158, 1057, 840.

1.24 (R)-I l-(4-Vinylphenoxy)undecyIoxy-2-(4-butyloxybenzoxy)-5-(4-(l-methyl heptyloxy)) benzoyloxy) benzoate (26)

A solution of (R)-2-(4-butoxybenzoyloxy)-5-(4-(l-methyl heptyloxy))benzoyl oxy) benzoic acid (0.4g, 0.71 mmol), 4-(ll-hydroxyundecyloxy)styrene (0.21g, 0.71 mmol), EDAC (0.14g, 0.71 mmol), DMAP (0.09g, 20mol%) in 30 mL dichloromethane was stirred for 9 days at room temperature. The reaction mixture was purified by column chromatography in 10:1 hexane/ethyl acetate mixture to give an off-white solid which was recrystallised from ethanol (2x) to yield a white solid (0.29g, 49%). Product was lost due to an experimental mishap; Thermal transitions ⁰C₃ K 46.4 N* (29.2) I; (Elemental Analysis for C₅₂H₆₆O₉: C, 74.79; H, 7.97; O, 17.24, Found: C, 74.11, H, 7.95); δ_H (CDCl₃, 400MHz, 25°C) 0.81 (3H, t, J 6.7), 0.91 (3H, t, J 7.3), 1.09-1.75 (35H, m), 3.85 (2H₅ 1, J 6.6), 3.96 (2H, t, J 6.4), 4.07 (2H, t, 6.9), 4.40 (IH, sext, J6.1), 5.02 (IH₃ dd, J 0.8, 11.0), 5.51 (IH, dd₅ J 0.8, 17.7), 6.56 (IH, dd, J 11.0, 17.7), 6.76 (2H, d, J 8.5), 6.89 (4H, m), 7.17 (IH, d, J 8.9), 7.24 (2H, d, J 8.5), 7.36 (IH, dd, J 3.0, 8.9), 7.81 (IH, d, J 3.0), 8.07 (4H, m); m/z (APCI) 857 (M⁺ + Na⁴) ;FTIR V₁^_x cm^'1; 2917, 1729, 1604, 1510, 1420, 1244, 1159, 1055, 836.

1.25 (jR)-ll-(4-Vinylphenoxy)undecyloxy-2-(4-heptyloxybenzoyloxy)-5-(4-(l- methyl heptyloxy))benzoyloxy) benzoate (27) A solution of (R)-2-(4-heptyloxybenzoxy)-5-(4-(l -methyl heptyloxy))benzyl oxy) benzoic acid (0.4g, 0.66 mmol), 4-(l l-hydroxyundecyloxy)styrene (0.19g, 0.66 mmol), EDAC (0.13g, 0.66 mmol), DMAP (0.08g, 20mol%) in 30 niL dichloromethane were stirred for one week at room temperature. The reaction mixture was purified by column chromatography in 10:1 hexane/ethyl acetate mixture to give a white solid which was recrystallised from ethanol. (0.23g, 40%); Thermal transitions ⁰C, K 37.2 N* (29.2) I; (Elemental Analysis for C₅₅H₇₂O₉: C, 75.31; H, 8.27; 0, 16.42, Found: C, 75.15, H, 8.24); δ_H (CDCl₃, 400MHz, 25⁰C) 0.81 (3H, t, J 7.0), 0.83 (3H, t, 6.7), 1.10-1.78 (41H, m), 3.87 (2H, t, J 6.6), 3.96 (2H, t, J 6.6), 4.07 (2H, t, J 6.7), 4.41 (IH, sext, J 6.1), 5.03 (IH, dd, J 0.9, 11.0), 5.52 (IH, dd, J 0.9, 17.4), 6.57 (IH, dd, J 11.0, 17.4), 6.77 (2H, d, J 8.9), 6.89 (4H, dd, J 6.4, 8.9), 7.18 (IH, d, J 8.9), 7.25 (2H, d, J 8.9), 7.37 (IH, dd, J 3.0, 8.9), 7.81 (IH, d, J 3.0), 8.07 (4H, m); m/z (APCI) 899.5 (M⁺ + Na⁺; ; FTIR v_max cm^"1; 2927, 1730, 1603, 1510, 1419, 1244, 1159, 1058, 837.

2. Synthesis of Polymer by Solution Polymerisations

2.1 Poly[(4-acryloyloxybutyl) 2,5-di(4-butoxybenzoyloxy) benzoate] (P19)

To a cooled solution of ABCN (1.2mg, 3 mol%) in toluene (0.9g₅ 1.0 mL) in a glass ampoule, the monomer 19 (lOOmg, 0.158 mmol) was added, and the solution degassed and vented with nitrogen three times. The ampoule was then placed in an oil bath preheated to 85°C and sealed. The solution was stirred at 85°C for 7 days, cooled to room temperature and the polymer precipitated by dropwise addition of the solution into hexane. The polymer was re-precipitated from DCM into methanol. The polymer was then isolated as a colourless amorphous solid by filtration (49.8mg, 50%); Thermal transitions °C, g 35 N 86.7 1; M_n 7800 gmol^"1, M_w 10600 gmol^"1 PD 1.4; δ_H (CDCl₃, 400MHz, 25⁰C) 0.90 (6H, br.m), 1.18-2.28 (15H, br.m), 3.95 (8H, br.m), 6.86 (4H, br.m), 7.16 (IH, br.s), 7.36 (lH,br.s), 7.77 (IH, br.s), 8.04 (4H, br.m) FTIR V_max cm^"1; 2964, 2881, 1734, 1603, 1509, 1420, 1243, 1158, 1047, 1004, 841.

2.2 Poly[(4-methacryloyloxybutyl) 2,5-di(4-butoxybenzoyloxy) benzoate] (P20)

To a cooled solution of ABCN (1.2mg, 3 mol%) in toluene (0.9g, 1.0 mL) in a glass ampoule ,the monomer 20 (lOOmg, 0.155 mmol) was added, and the solution degassed and vented with nitrogen three times. The ampoule was then placed in an oil bath preheated to 85°C and sealed. The solution was stirred at 85°C for 66 hrs, cooled to room temperature and the polymer precipitated by dropwise addition of the solution into hexane. The polymer was re-precipitated from DCM into methanol. The polymer was then isolated as a colourless amorphous solid by filtration (36mg, 36%). Thermal transitions ⁰C, g 50 N 81.6 1; M_n 10200 gmol^"1, M_w 15300 gmol^"1 PD 1.5; δ_H (CDCl₃, 400MHz, 25°C) 0.91-1.10 (br.m, 9H)₅ 1.42-1.78 (14H, br.m), 3.63-4.04 (8H₅ br.m), 6.86 (4H₅ br.m), 7.13 (IH₅ br.s)₅ 7.34 (IH₅ br.s), 7.77 (IH₅ br.s), 8.04 (4H, br.m) FTIR V_m3x Cm^"1; 296O₅ 1726, 1604, 151O₅ 142I₅ 1245, 1157, 1053.

2.3 Poly[(4-methacryloyloxybiityl) 2,5-di(4-heptyloxybenzoyloxy) benzoate] (P21) To a cooled solution of ABCN (l.Omg, 3 mol%) in toluene (0.9g, 1.0 mL) in a glass ampoule, the monomer 21 (lOOmg, 0.137 mmol) was added, and the solution degassed and vented with nitrogen three times. The ampoule was then placed in an oil bath preheated to 85⁰C and sealed. The solution was stirred at 85°C for 7 days, cooled to room temperature and the polymer precipitated by dropwise addition of the solution into ether. The polymer was re-precipitated from DCM into methanol. The polymer was then isolated as a colourless amorphous solid by centrifugation (18.4mg, 18%). Thermal transitions ⁰C₃ g 25 N 51.9 I; M_n 12500 gmol^"1, 20000 gmol^"1 PD 1.6; δ_H (CDCl₃, 400MHz₅ 25⁰C) 0.81-1.13 (9H, br.s), 1.23-1.70 (26H₅ br.m), 3.91 (8H, br.m), 6.85 (4H₅ br.m), 7.15 (IH, br.s), 7.34 (IH, br.s), 7.77 (IH₅ br.s), 8.01 (IH, br.m) FTIR V_n38x cm^"1; 2927, 1728, 1603, 1510, 1419, 1243, 1159, 1055, 842.

2.4 Poly[(i?)-(4-methacryloyloxybutyl)-2-(4-butoyloxybenzoyloxy)-5-(4-(l- methyl heptyloxy))benzoyloxy) benzoate] (P22)

To a cooled solution of ABCN (l.Omg, 3 mol%) in toluene (0.9g, 1.0 mL) in a glass ampoule ,the monomer 22 (lOOmg, 0.142 mmol) was added, and the solution degassed and vented with nitrogen three times. The ampoule was then placed in an oil bath preheated to 85°C and sealed. The solution was stirred at 85°C for 7 days, cooled to room temperature and the polymer precipitated by dropwise addition of the solution into methanol. The polymer was re-precipitated from DCM into methanol. The polymer was then isolated as a colourless, viscous liquid by centrifugation (57.0mg, 57%); Thermal transitions ⁰C₃ g 21 1; M_n 13300 gmol^"1, M_w 54800 gmol^"1 PD 4.1; 5H (CDCl₃, 400MHz, 25°C) 0.64-0.95 (9H, br.m), 1.21-1.64 (23H, br.m), 3.63-4.00 (6H₃ br.m), 4.40 (IH, br.m), 6.81-6.92 (4H₃ br.m), 7.10 (IH₃ br.m), 7.28-7.37 (IH, br.m), 7.74-7.81 (IH, br.m), 7.97-8.10 (4H, br.m); FTIR v_mas cm^'1; 2927, 1724, 1603, 1509, 1422, 1243, 1158, 1054, 844.

2.5 Poly[(i?)-(4-methacryloyloxybutyl)-2-(4-heptyloxybenzoyloxy)-5-(4-(l- methyl heptyloxy))benzoyloxy) benzoate] (P23)

To a cooled solution of ABCN (l.Omg, 3 mol%) in toluene (0.9g₃ 1.0 mL) in a glass ampoule, the monomer 23 (lOOmg, 0.134 mmol) was added, and the solution degassed and vented with nitrogen three times. The ampoule was then placed in an oil bath preheated to 85°C and sealed. The solution was stirred at 85°C for 7 days, cooled to room temperature and the polymer precipitated by dropwise addition of the solution into methanol. The polymer was re-precipitated from DCM into methanol. The polymer was then isolated as a colourless, viscous liquid by centrifugation (61.7mg,

62%); Thermal transitions ⁰C, g 12 1; M_n 14500 gmol^"1, M_w 31000 gmol^"1 PD 2.4; δ_H (CDCl₃₃ 400MHz, 25°C) 0.80 (6H₃ br.s), 1.22-1.84 (32H₃ br.m), 3.68-4.15 (6H₃ br.m), 4.40 (IH₃ br.m), 6.98-6.92 (4H₃ br.m), 7.15 (IH₃ br.m), 7.34 (IH₃ br.m), 7.77

(IH, br.s), 8.02-8.10 (4H₃ br.m); FTIRV_n18x cm^'1; 2921, 1734, 1603, 1507, 142O₃ 1244, 1158, 1053, 844. 2.6 Poly[ll-(4-vinylphenoxy)imdecyloxy 2,5-di(4-butoxybenzoyIoxy) benzoate] (P24)

To a cooled solution of ABCN (0.9mg, 3 mol%) in toluene (0.9g, 1.0 niL) in a glass ampoule, the monomer 8 (lOOmg, 0.129 mmol) was added, and the solution degassed and vented with nitrogen three times. The ampoule was then placed in an oil bath preheated to 85°C and sealed. The solution was stirred at 85°C for 6 days, cooled to room temperature and the polymer precipitated by dropwise addition of the solution into ether. The polymer was re-precipitated from DCM into methanol. The polymer was then isolated as a colourless amorphous solid by filtration (26.2mg, 26%); Thermal transitions ⁰C₃ g 27 N 77.2 1; M_n 28200 gmol^"1, M_w 56500 gmol^"1 PD 2.0; δ_H (CDCl₃, 400MHz, 25°C) 0.89-0.94 (6H, br.m), 1.10-1.70 (33H, br.m), 3.94-4.08 (8H, br.m), 6.06-6.61 (4H, br.m), 6.87-6.92 (4H, br.m), 7.14-7.20 (IH, br.m), 7.80-7.83 (IH, br.m), 8.05-8.11 (4H, br.m); FTIR V_1113x cm⁴; 2928, 1729, 1604, 1509, 1420, 1255, 1160, 1055, 845.

2.7 Poly[(ϋ-)-ll-(4-vinyIphenoxy)undecyIoxy-2-(4-butyloxybenzoxy)-5-(4-(l- methyl heptyloxy))benzyloxy) benzoate] (P26)

To a cooled solution of ABCN (l.Omg, 3 mol%) in toluene (0.9g, 1.0 mL) in a glass ampoule the monomer 26 (lOOmg, 0.134 mmol) was added, and the solution degassed and vented with nitrogen three times. The ampoule was then placed in an oil bath preheated to 85°C and sealed. The solution was stirred at 85°C for 7 days, cooled to room temperature and the polymer precipitated by dropwise addition of the solution into methanol. The polymer was re-precipitated from DCM into methanol. The polymer was then isolated as a colourless amorphous solid by centrifugation (85.8mg, 86%); Thermal transitions ⁰C, g 9 I; M_n 24200 gmol^"1, M_w 57300 gmol^"1 PD 2.4; δ_H (CDCl₃, 400MHz₅ 25⁰C) 0.80-0.94 (6H, br.m), 1.10-1.76 (39H, br.m), 3.75-4.09 (6H₃ br.m), 4.38-4.42 (IH, br.m), 6.25-6.65 (4H, br.m), 6.78-6.91 (4H, br.m), 7.09-7.17 (IH, br.m), 7.34-7.39 (IH, br.m), 7.76-7.82 (IH, br.m), 8.03-8.12 (4H, br.m); FTIR _Vmax cm^"1; 2929, 1730, 1603, 1507, 1420, 1242, 1159, 1052, 844.

3. Microsphere synthesis by suspension polymerisation

3.1 iV^-poly[(4-methacryloyloxybutyl)-2,5-di(4->butoxybenzoyloxy) benzoate]-

/-1,6-dihexanediol methacrylate (MS20) PVA (0.7g) was refluxed in 25ml water until dissolved, the solution allowed to cool to room temperature, and 10 mL of water were added. Boric acid (0.3g) was dissolved in 8.75 mL water and added slowly to the PVA mixture whilst stirring. Of the resulting PVA/boric acid solution, 15 mL was added to a suspension polymerisation reactor. A mixture of monomer 20 (2g, 3.09 mmol), 1,6-dihexandiol methacrylate (7.9mg, 1 mol%) and ABCN (22.7mg, 3 mol%) was then added to the PVA mixture, followed by another 15 mL of the PVA/boric acid solution. The reactor was then placed in a water bath, pre-heated to 80°C and stirred vigorously with an overhead stirrer until, after about 2 minutes, the monomer phase was completely melted and a smooth emulsion was formed. The stirring rate was then reduced to 600 rpm and the mixture was stirred for three hours at 80⁰C under N₂. After cooling to room temperature, 200 mL of deionised water was added. The resulting mixture was gently stirred for one hour and left to settle overnight. The top layer was decanted, replaced with 200 mL water, the mixture again gently stirred for one hour and left to settle. This process was repeated 3 times before the remaining white, solid particles were filtered through a number 3 sinter, dried in a desiccator, purified via soxhlet extraction with DCM overnight and dried in a vacuum desiccator to obtain birefringent beads with some polymer of undefined morphology (197mg, 9.8%); Thermal transitions ⁰C, g 57 N 72.01; FTIR v_max cm^"1; 2958, 1735, 1604, 1507, 1424, 1234, 1155, 1052.

3.2 iVeϊ-poly[(4-methacryloyloxybutyl)-2,5-di(4-heptyloxybenzoyloxy) benzoate]-/-l,6-dihexanediol methacrylate (MS21)

PVA (0.7g) was refluxed in 25ml water until dissolved, the solution allowed to cool to room temperature and 10ml of water added. Boric acid (0.3g) was dissolved in 8.75 ml water and added slowly to the PVA mixture whilst stirring. Of the resulting PVA/boric acid solution, 30 mL was added to a suspension polymerisation reactor, and the reactor placed in a water bath, pre-heated to 80⁰C. A mixture of monomer 12 (2g, 2.74mmol), 1,6-dihexanediol methacrylate (7.0mg, 1 mol%) and ABCN (20.1 mg, 3 mol%) was then added to the PVA mixture and stirred vigorously with an overhead stirrer until after two minutes the monomer phase was completely melted and a smooth emulsion was formed. The stirring rate was then reduced to 600 rpm and the mixture was stirred overnight at 80⁰C under N₂. After cooling to room temperature, 200 mL of water was added. The resulting mixture was gently stirred for one hour and left to settle overnight. The top layer was decanted, replaced with 200 mL water, the mixture again gently stirred for one hour and left to settle. This process was repeated 3 times before the remaining white, solid particles were filtered through a number 3 sinter, dried in a desiccator, purified via soxhlet extraction with DCM overnight and dried in a vacuum desiccator to obtain birefringent beads (176mg, 8.8%); Thermal transitions ⁰C, g 40 N 61.3 I; FTIR v_max cm^"1; 2927, 1724, 1604, 1509, 1420, 1241, 1159, 1051, 846. 3.3 iVeϊ-poly[ll-(4-vinyIphenoxy)undecyloxy-2,5-i(4-butoxybenzoyloxy) benzoate]-i-l,10-di(vinylphenoxy)decane (MS24)

PVA (0.7g) was refluxed in 25ml water until dissolved, the solution allowed to cool to room temperature, and 10 mL of water were added. Boric acid (0.3g) was dissolved in 8.75 mL water and added slowly to the PVA mixture whilst stirring. Of the resulting PVA/boric acid solution, 15 mL was added to a suspension polymerisation reactor. A mixture of monomer 24 (2g, 2.57 mrnol), l,10-di(vinylphenoxy)decane (9.7mg, 1 mol%) and 20.1 mg ABCN (18.8mg, 3 mol%) was then added to the PVA mixture, followed by another 15 mL of the PVA/boric acid solution. The reactor was then placed in a water bath, pre-heated to 85⁰C and stirred vigorously with an overhead stirrer until after about 2 minutes the monomer phase was completely melted and a smooth emulsion was formed. The stirring rate was then reduced to 600 rpm and the mixture was stirred for 12 hours at 80⁰C under N₂. After cooling to room temperature, 200 mL of deionised water was added. The resulting mixture was gently stirred for one hour and left to settle overnight. The top layer was decanted, replaced with 200 mL water, the mixture again gently stirred for one hour and left to settle. This process was repeated 3 times before the remaining white, solid particles were filtered through a number 3 sinter, dried in a desiccator, purified via soxhlet extraction with DCM overnight and dried in a vacuum desiccator to obtain birefringent beads with some aggregation (380mg, 19.0%); Thermal transitions ⁰C, g 30 N 65.1 I; FTIR v_max cm^"1; 2927, 1734, 1603, 1507, 1245, 1155, 1064, 849. 3.4 iVer-poly^ll-methacryloyloxyundecany^-l-S-d^-heptyloxybenzoyloxy) benzoate]-/-l,6-dihexanediol methacrylate (MS18a)

PVA (0.7g) was refluxed in 25ml water until dissolved, the solution allowed to cool to room temperature and 10ml of water added. Boric acid (0.3g) was dissolved in 8.75 ml water and added slowly to the PVA mixture whilst stirring. Of the resulting PVA/boric acid solution, 30 mL was added to a suspension polymerisation reactor, and the reactor placed in a water bath, pre-heated to 80 ⁰C. A mixture of monomer 18 (2g, 2.41mmol), 1,6-dihexanediol methacrylate (6.4mg, 1 mol%) and ABCN (17.7mg, 3 mol%) was then added to the PVA mixture and stirred vigorously with an overhead stirrer until after two minutes the monomer phase was completely melted and a smooth emulsion was formed. The stirring rate was then reduced to 600 RPM and the mixture was stirred overnight at 8O⁰C under N₂. After cooling to room temperature, 200 mL of water was added. The resulting mixture was gently stirred for one hour and left to settle overnight. The top layer was decanted, replaced with 200 mL water, the mixture again gently stirred for one hour and left to stand. This process was repeated 3 times before the remaining white, solid particles were filtered through a number 3 sinter, dried in a desiccator, purified via soxhlet extraction with DCM overnight and dried in a vacuum desiccator to obtain birefringent beads with some aggregation (397 mg, 19.8%); Thermal transitions ⁰C, g 19 N 69.7 1; FTJRv_1113x cm^'1; 292I₅ 1734, 1604, 1507, 1420 1246, 1160, 1057, 842.

3.5 iVε*-poly[(ll-methacryIoyloxyundecanyl)-2,5-di(4-heptyloxybenzoyIoxy) benzoate]-i-l,6-dihexanediol methacrylate (MS18b)

PVA (0.875g) was refluxed in 25ml water until dissolved, the solution allowed to cool to room temperature and 10ml of water added. Boric acid (0.3g) was dissolved in 8.75 ml water and added slowly to the PVA mixture whilst stirring. Of the resulting PVA/boric acid solution, 30 mL was added to a suspension polymerisation reactor. A mixture of monomer 18 (2g, 2.41mmol), 1,6-dihexanediol methacrylate (6.4mg, 1 mol%) and ABCN (17.7mg, 3 mol%) in 1 g toluene was then added to the PVA mixture and stirred vigorously with an overhead stirrer until after about 2 minutes the monomer phase was completely melted and a smooth emulsion was formed. The reactor was then placed in a water bath, pre-heated to 80°C, the stirring rate reduced to 600 rpm and the mixture was stirred overnight at 80⁰C under N₂. After cooling to room temperature, 200 mL of water was added. The resulting mixture was gently stirred for one hour and left to settle overnight. The top layer was decanted, replaced with 200 mL water, the mixture again gently stirred for one hour and left to settle. This process was repeated 3 times before the remaining white, solid particles were filtered through a number 3 sinter, dried in a desiccator, purified via soxhlet extraction with DCM overnight and dried in a vacuum desiccator to obtain birefringent beads (862mg, 49.1%); Thermal transitions ⁰C₅ g 18 N 69.5.7 I; FTIR v_max cm^"1; 2927, 1734, 1604, 1507, 1244, 1160, 1057, 844.

Tables

Table 1

The structures of the final liquid crystal compounds were checked by the analytical methods proton NMR, IR, mass spectrometry and elemental analysis as described in the experimental section. The thermal phase properties were analysed by differential scanning calorimetry (DSC) and polarising optical microscopy (POM). Table 1 lists the transition temperatures observed in the DSC when carried out at a heating rate of 10°C min^"1.

Table 1: DSC transition temperatures and corresponding ΔH {Jg^"1} values of transitions observed by heating runs at 10°C min^"1. ( ) denotes a monotropic phase.

Table 2

Table 2 lists the molecular weight averages and polydispersities obtained by triple detection GPC analysis of the polymers in THF, as well as the glass transition T_g and N-I temperatures observed in DSC heating runs at 1O⁰C min^"1.

Table 2: GPC data for the weight average molecular weight (M_w) in g mol^"1, the number average molecular weight (M_n) in g mol^"1. polydispersity (PD) and degree of polymerisation (DP), as well as DSC transition temperatures and corresponding ΔH {Jg^"1} values of transitions observed in heating runs at 10⁰C min^"1.

Table 3

Table 3: Table representing the varied suspension polymerisation conditions, yield and size of polymer microspheres synthesised. Size distribution measured in % standard deviation. DSC transition temperatures and corresponding ΔH (Jg^"1 } values of transitions observed by heating runs at 10⁰C min^"1. (* size determined from small sample).

4. Examination of Birefringent Polymer Beads

For example, the birefringent polymer beads were examined for their elastic response to an external mechanical disturbance. A suspension of polymer beads in silicon oil was filled between a glass slide and cover slip, placed in the hot stage of an optical microscope and heated above the glass transition. The cover slip was then gently tipped with a pair of tweezers and the response observed by polarising optical microscopy. It was observed that the beads remained mobile throughout the experiment as the silicon oil prevented surface interactions and attachment to the glass surfaces. Figure 5 shows consecutive frames of a polarising optical microscopy video taken during the mechanical deformation of a bead of MS 18b at 57°C.

Claims

Claims

1. A cross-linked polymer bead comprising one or more laterally attached mesogenic groups.

2. A cross-linked polymer bead according to claim 1 wherein the bead is elastic.

3. A cross-linked polymer bead according to claim 1 wherein the one or more lateral mesogenic units is based upon the structure of a compound of formula I;

./Cp Xφ .Xp

formula I in which R¹ and R⁴, which may be the same or different, are each alkyl Cl to 20, alkenyl C2 to 20, alkynyl C2 to 20, haloalkyl Cl to 20, haloalkenyl C2 to 20, haloalkynyl C2 to 20, -(SiO)_a(CH₂)_v- or (-OCH₂CH₂-)_W or one of R¹ and R⁴ is -CN, - NC, -NO₂, -NCS, -SCN, -CF₃, -OCF₃; X¹ and X⁴, which may be the same or different, are each -O-, -S-, -C(O)O-, -OC(O)-, -C(O)S-, -SC(O)-, -C(O)NR⁵, -NR⁶C(O)- Or-SiR⁷R⁸;

R² and R³, which may be the same or different, are each cycloalkyl C3 to 12, 3 to 12 membered heterocycloalkyl, a 6 to 14 membered aryl or a 5 to 14 membered heteroaryl, each of which may be optionally fused to an aryl and each of which may be optionally substituted by one or more substituents selected from halogen or alkyl Cl to 20; X² and X³, which may be the same or different, are each -C(O)O-, -OC(O)-, -C(O)S-, -SC(O)-, -C(S)O-, -OC(S)-, -C(S)S-, -SC(S)-, (-CH₂CH₂-)_ml, (-CH=CH-)_m2, (-C≡C-)^, -CH=N, -CH₂O-, -OCH₂-, -CH₂S-, -SCH₂-, -N=N-, a carborane or a tricyclic hydrocarbon, such as adamantane; and Y is cycloalkyl C3 to 12, 4 to 12 membered heterocycloalkyl, a 6 to 14 membered aryl or a 5 to 14 membered heteroaryl, each of which may be optionally substituted by one or more substituents selected from halogen or alkyl Cl to 20; the group X_p represents the linkage to a polymerisable unit of the polymer, e.g. is - OCH₂-, -OC(O)CH₂- or -C(O)OCH₂-, or a single bond, provided that only one R², R³ and Y is provided with such a connection to the polymerisable unit;

R⁵ and R⁶, which may be the same or different, are each hydrogen or alkyl Cl to 6; R and R , which may be the same or different, are each alkyl Cl to 6; n, m, q, r, s and t which may be the same or different, are each O or 1; a, v, m , m and m , which may be the same or different, are each an integer 1 or 2; w is an integer 1, 2 or 3; and isomers thereof.

4. A cross-linked polymer bead according to claim 3 wherein the polymerisable units are based on acrylates and/or styrene.

5. A cross-linked polymer bead according to claim 4 wherein the acrylate is a methacrylate.

6. A cross-linked polymer bead according to claim 3 wherein the lateral mesogenic units are based upon benzyl dihydroxy benzoates of formula II; formula Il

wherein R¹ and R⁴, which may be the same or different, are each alkyl Cl to 20.

7. A cross-linked polymer bead according to claim 1 wherein one of R¹ and R⁴ is chiral.

8. A cross-linked polymer bead according to claim 1 wherein the surface of the bead is derivatised.

9. A cross-linked polymer bead according to claim 1 wherein the liquid crystal mesogen comprises a compound of general formula VII;

(R\-(X\-R²-(X²)_τ-Y^LC-(X\R³-(X⁴)r(R⁴)_m

formula VII R¹, R², R³, R⁴, X¹, X², X³, X⁴, X_p, n, m, q, r, s and t are each as hereinbefore defined; and Y^LC is cycloalkyl C3 to 12, 4 to 12 membered heterocycloalkyl, a 6 to 14 membered aryl or a 5 to 14 membered heteroaryl, each of which is substituted by a polymerisable unit.

10. A cross-linked polymer bead according to claim 1 wherein the liquid crystal mesogen comprises a compound of general formula IV

wherein R¹ and R⁴ which may be the same or different, are each alkyl Cl to 20; and RL_C is a polymerisable unit.

11. A cross-linked polymer bead according to claims 9 or 10 wherein RL_C is;

or

in which n is an integer from 1 to 20.

12. A cross-linked polymer bead according to claim 1 wherein the cross-linked polymer is selected from the group consisting of; poly[(4-acryloyloxybutyl) 2,5-di(4-butoxybenzoyloxy)benzoate] (P19); poly[(4-methacryloyloxybutyl) 2_J5-di(4-butoxybenzoyloxy)benzoate] (P20); poly[(4-methacryloyloxybutyl) 2,5-di(4-heptyloxybenzoyloxy)benzoate] (P21); poly[(R)-(4-methacryloyloxybutyl)-2-(4-butoyloxybenzoyloxy)-5-(4-(l-methyl heptyloxy))benzoyloxy)benzoate] (P22); poly[(i?)-(4-methacryloyloxybutyl)-2-(4-heptyloxybenzoyloxy)-5-(4-( 1 -methyl heptyloxy))benzoyloxy)benzoate] (P23); poly[l l-(4-vinylphenoxy)undecyloxy 2,5-di(4-butoxybenzoyloxy)benzoate] (P24); and poly[(i?)-ll-(4-vinylphenoxy)undecyloxy-2-(4-butyloxybenzoxy)-5-(4-(l-methyl heptyloxy))benzyloxy)benzoate] (P26).

13. A cross-linked polymer bead according to claim 1 wherein the cross-linked polymer bead is a polymer microsphere selected from the group consisting of; iVet-poly[(4-methacryloyloxybutyl)-2,5-di(4-butoxybenzoyloxy)benzoate]-/-l_:>6- dihexanediol methacrylate (MS20);

JVet-poly [(4-methacryloyloxybutyl)-2,5-di(4-heptyloxybenzoyloxy) benzoate]-*- 1 ,6- dihexanediol methacrylate (MS21);

Afef-poly[l 1 -(4-vinylρhenoxy)undecyloxy-2,5-i(4-butoxybenzoyloxy) benzoate]-/- l,10-di(vinylphenoxy)decane (MS24);

51 Afø-poly[(l 1 -methacryloyloxyundecanyl)-2,5-di(4-heptyloxybenzoyloxy) benzoate]- z-l,6-dihexanediol methacrylate (MS18a); and

JVet-poly[(l 1 -methacryloyloxyundecanyl)-2,5-di(4-heptyloxybenzoyloxy) benzoate]- /-1,6-dihexanediol methacrylate (MS18b).

14. A method of preparing a liquid crystal of formula IV according to claim 2 which comprises reacting a compound of formula II;

formula Il

wherein R¹ and R⁴, which may be the same or different, are each alkyl Cl to 20. with a compound of formula V or VI;

formula V

formula Vl

in which n is an integer from 1 to 20.

15. A method of manufacturing a cross-linked polymer bead comprising a liquid crystal core which comprises heterogeneous polymerisation of a polymerisable monomer which monomer comprises one or more lateral mesogenic units.

16. A sensor comprising a cross-linked polymer bead comprising a liquid crystalline core.

17. The use of liquid crystal according to claims 9 or 10 in the manufacture of a cross-linked polymer bead comprising a liquid crystalline core.

18. A cross-linked polymer bead, compound, liquid crystal or process as hereinbefore described with reference to the accompanying examples.