DD289278A5 - PROCESS FOR PREPARING NEW LIQUID CRYSTALLINE COPOL (METHACRYLOYLOXYALKYLENEOXYBENZOESAEURE-P-ALKOXY-ANILID-METHACRYLOYLOXYALKANE) - Google Patents

Abstract

The invention relates to a process for the preparation of novel liquid-crystalline copoly (methacryloyloxyalkylenoxybenzoic acid p-alkoxyanilide-methacryloyloxyalkane), which in combination with low molecular weight liquid crystals in electro-optical display elements, as polymers with memory effect in information storage and image recognition devices or as films, films or layers , on or between transparent plates, for controlling the transmission or the polarization plane of transmitted or reflected light. {Methacryloyloxyalkyleneoxybenzoic acid p-alkoxyanilide; alkyl methacrylate; copolymerization; liquid crystal; Copoly (methacryloyloxyalkylenoxybenzoesaeure-p-alkoxyanilidmethacryloyloxyalkan)}

Description

(CH ₉ ),

CH I

-CH ₉ -C- ² I CO

0-

- <o> CO-NH- <o> -OR

in the

R ¹ - an alkyl radical having 1 to 4 carbon atoms

R ^{2 represents} an alkyl radical having 1 to 8 C-atoms or a cycloalkyl radical, η = 2 to 6

m = 10 to 200 and

a + b = 1, where O, 99> a> 0.85 and O, 01 <b <0.15,

characterized in that methacryloyloxyalkylenoxybenzoic acid p-alkoxyanilides of the general formula II

CH,

I '

O = CO- (CH ₉ ) -O- <o> CONH <o> OFc ^l wherein R ¹ and η have the meaning given, and alkyl methacrylates of the general formula

CH,

I *

Ir> '

O = C-O-R ^

in which R ² has the meaning mentioned in relation IhIII = 99: 1 to 85: 15in the presence einosmäßig polar organic solvent and a polymerization initiator at temperatures of 50 to 80 ^c C are copolymerized under inert conditions.

2. The method according to claim 1, characterized in that are used as a moderately polar solvent toluene, tetrahydrofuran, dioxane or mixtures thereof.

3. The method according to claim 1, characterized in that the polymerization initiator is used with a molar fraction of 0.2 to 2%, based on the sum of the monomers.

Λ. Process according to claims 1 and 3, characterized in that are used as the polymerization initiator, known initiators of polymerization radüalischen whose decomposition begins at about 5O ⁰ C.

5. Process according to Claims 1, 3 and 4, characterized in that azobisisobutyronitrile is preferably used as the polymerization initiator.

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Field of application of the invention

The invention relates to a process for the preparation of novel liquid-crystalline Copolylmethacryloyloxyalkylenoxybenzoesäure-palkoxyanilid-methacryloyloxyalkane), in combination with low molecular weight liquid crystals in electro-optical display elements, as polymers with memory-tiffekt in information storage and image recognition devices or as films, films or layers, on or between translucent plates, to control the transmission or the plane of polarization of transmitted or reflected light application.

Characteristic of the known state of the art

The synthesis of polymers with liquid-crystalline properties, in which the structural elements (mesogens) which cause a certain phase arrangement are bound via flexible groups (spacers) as rare chains to a polymer main-chain (SCLCP) crystal is known. An overview of the basic types described so far is, for example, TS Chung in Polymer Engineering and Science, 26 (1986) p. 901. The liquid crystalline polymers have the advantage over the low molecular weight liquid crystals that no structural changes occur in the transition from the liquid crystalline phase to the solid phase Their application therefore does not have to take place in the "sealed state" and, in particular in the case of the copolymers, optimization and coordination of material and liquid crystal properties is possible, which makes them much easier to handle in practice Location of their Phasenübergangstomperaturen are dependent on the structure of the mesogenic side chain, in particular the Längso the spacer group that makes the connection to the polymer backbone, and to a limited extent on the molecular weight of the polymer.

Among the extensively studied side-chain liquid-crystalline polymers are the polydnethacryloyloxyalkyleneoxybenzoic acid p-alkyloxyphenyl esters) (M.Portugall, H.Rirjsdorf, R. Zentel, Makromol Chem, 183 [1982] p.2318). These polymers can be described by the following general formula IV:

0 = C-0 (CH ₉ ) 0- <o> -COO <o> OR

in which R represents an alkyl radical having 1 to 4 C atoms and η = 2 to 11 and m = 6 to 2 U0.

Their phase transition temperatures can therefore be used as an orientation comparison in the characterization of new SCLCPs. The polyimethacryloyloxyalkyleneoxybenzoic acid p-methoxyphenyl esters) have a nematic phase. For such polymers having molecular weights in the range from 50,000 to 80000 g / mol, the transition temperatures at η = 2: g / n = 101 ⁰ C, n / i = 121 ⁰ C and at η = β: g / n = 95 ⁰ C, n / i = 105 ⁰ C.

These values are, as limits of the liquid-crystalline state of this class of compounds, at the same time their maximum

Scope of application.

From our own investigations are also copolymers of Methacryloyloxyalkylenoxybenzoesäure p-alkoxyanilide with Methacryloyloxyalkylenoxybenzoesäure p-alkoxyphenylestern, in which the position and nature of the liquid-crystalline conversion ranges can be adjusted in a targeted manner on the copolymer composition. Here are monomers with potential mesogen (rigid, stä'ochenförmiges structural element with ester bond as a bridge member in the central structural unit and wing group) and monomers with analogous structure, which in themselves lead to crystalline products and do not form liquid crystalline phases (rigid, rod-shaped structural element with amide bond in central structural unit and wing group), and it is found that products with liquid-crystalline behavior become accessible over the entire range of the composition.

Object of the invention

The aim of the invention is liquid-crystalline polymers which enable an extension of the application areas for compounds with liquid-crystalline properties.

Explanation of the essence of the invention

The object of the invention is to provide new liquid crystalline polymers. The object is achieved by the preparation of novel liquid-crystalline Copolyfmethacryloyloxyalkylenoxybenzoesäure p-alkoxyanilid-methacryloxyalkerie) of the general formula I.

-CH ₉ -C-

^ί ι

< ^CH 2> n

O <o> -CO-NH- <o> -OR ^J

CO

¹ 2 OfT

in the

R ¹ - an alkyl radical having 1 to 4 carbon atoms

R ^{2 represents} an alkyl radical having 1 to 8 C atoms or a cycloalkyl radical,

η = 2 to 6

m = 10 to 200 and

a + b = 1, where 0.99> a> 0.85 and 0.01 <b <0.15,

dissolved by methacryloyloxyalkylenoxybenzoesäure p-alkoxyanilide of the general formula II

CH ₉ = C II,

I - 1

O = CO- (CH ₉₎ "- 0- <o> CONH- <g> OR ⁱ

Ct Π

where R ¹ and η have the same meaning, and alkyl methacrylates of the general formula III CHg

I CH ₂ = C Hl

O = COR ²

in which R ^{2 has} the meaning given, in the ratio 11: 111 = 99: 1 to 85:15 in the presence of a moderately polar organic solvent and a polymerization initiator having a molar fraction of 0.2 to 2% at temperatures of 5O ⁰ C to 8O ⁰ C are copolymerized under inert conditions.

The starting materials of the general formula II are z. B. thereby accessible that the 4- (ω-Methacryloyloxyalkylenoxybenzoesäuren) with a few drops of dimethylformamide and a trace of 2,4-di-tert-butylpheno! and transferred with thionyl chloride in the acid chlorides. After 15 to 30 minutes, a homogeneous solution of the acid chloride is present. This is taken up in a chlorinated hydrocarbon and at temperatures between 0 and ^{c 'r} -. Added rielhylamin to a mixture of anisidine and ^T in the same chlorinated hydrocarbon, so that a slight excess of the binding of the by-produced hydrochloric acid present while stirring to form the desired ω After dilution with further chlorohydrocarbon, addition of dilute hydrochloric acid and subsequent neutral washing with water, the reaction product immediately yields in very good yield These compounds and also the poly (methacryloyloxyalkyleneoxybenzoic acid p-alkoxyanilides show no liquid-crystalline behavior and have a fixed melting point.

The copolymerization of these alkoxyanilides of the general formula II with the alkyl methacrylates of the general formula III is carried out in containers prepurified with pure nitrogen (ampoules). The monomers and the initiator are dissolved in moderately polar solvents such as toluene, tetrahydrofuran, dioxane or solvent mixtures. As initiators compounds are suitable whose decomposition starts at about 5O ⁰ C. Azo-bis-isobutyronitrile also proves to be particularly suitable because of the good possibility of its fineness and excellent handleability. Depending on the desired degree of polymerization, the concentration of the initiator is selected between 0.2 and 2 mol%, based on the sum of the monomer weight. The polymerization temperatures to values between 50 and 8O ⁰ C. The polymerization time is 50 to 96 hours. The products are then precipitated in methanol and purified several times by reprecipitation with tetrahydrofuran / ethanol. Finally, in a vacuum oven at 45-5O ⁰ C dried. Dio copolymers are obtained as pure white, powdered products. Their composition is controlled by elemental analysis. Liquid crystalline behavior is determined by differential calorimetry and polarization microscopy.

The copolyfmethacryloyloxyalkyleneoxybenzoic acid p-alkoxyanilide-methacryloyloxyalkanes), in contrast to the homopolymeric polylmethacryloyloxyalkyleneoxybenzoic acid p-alkoxyanilides, are found to be liquid crystalline within certain ranges of the composition. They have a smectic phase. The expansion of the liquid-crystalline phase can be varied selectively with the copolymer composition.

embodiments

Preparation of methacryloyloxyhexyleneoxybenzoic acid p-methoxyanilide

3.6 g (0.03 mol) of methacryloyloxyhexyleneoxybenzoic acid are dissolved in 20 ml of thionyl chloride with stirring at room temperature after addition of 4 drops of dimethylformamide and a trace of 2,4-di-tert-butylphenol. After about 15 minutes, the insoluble acid is converted into the soluble acid chloride.

The acid chloride is dissolved after distilling off excess thionyl chloride in 50 ml of chloroform and added dropwise with ice cooling and stirring to a mixture of 3.7 g of p-anisidine, 6 ml of triethylamine and 50 ml of chloroform. After 1 to 4 hours, it is diluted with a further 100 ml of chloroform and the solution is washed first with dilute hydrochloric acid and then several times with water until neutral. After drying with sodium sulfate and distilling off the solvent, the crude product is recrystallized from! Sopropanol.

There are 9.6 g, ie 77.4% of theory, thin-layer chromatography pure Methacryloyloxyhexylenoxybenzoesäunvpmethoxyanilid (F: 135.6 to 136.1 ⁰ C). Elementary analysis determines the following values:

calculated found C 70.05% 70.3% H 7.1% 7.2% N 3.4% 3.3%

Examples 1 to 3

1 g of methacryloyloxyhexyleneoxybenzoic acid p-methoxyanilide are dissolved in 30 ml of tetrahydrofuran with the appropriate amount of cyclohexylmethyl acrylate and transferred into a pure nitrogen prepurgitated ampoule into which azo-bis-isobutyronitrile has been previously weighed with a mole fraction of 2% (based on the total amount of monomer). The vessel is closed and

in the thermostat, the polymerization takes place at 6O ⁰ C over 60 send. After cooling, the ampoule is opened and the contents are added to 350 ml of methanol. The polymer precipitates Mz .läiiier precipitate. For purification, twice with tetrahydrofuran / ethanol precipitated and finally dried at 45 ° C in a vacuum to constant weight. The exact composition, the yield and the results of the DSC analysis are shown in the following table and the phase diagram in Figure 1, in which I for the structural element

I CH ₃ --C-CO-O - (CH ₂ ; ₆ -O- <9> C0NH- <o> -OCH ₃

CH ₉

I ^Z

and II for the structural element

CHo-C-CO-O- "J I stands. - <H> 5 example 2 3 I CH ₂ 70.6 10 15 cyclohexyl 70.12 71.8 66.7 Mole fraction in% 1 70.12 Yield in% 7,325 70.18 70.25 Elemental analysis in% 7.23 70.15 70.02 C: calculated 3.23 7.35 7.47 found 3.31 7.28 7.33 H: calculated g 333 s 3681 3.06 2.89 found 3.25 3.18 N: calculated g 338 s 363 i g343i found DSC analysis in K

Example 4

1 g of methacryloxyhexyleneoxybenzoic acid p-methoxyanilide is copolymerized with 0.018 g of n-butyl methacrylate (5 molar parts in%) in 30 ml of tetrahydrofuran with the addition of 0.0084 g of azo-bis-isobutyronitrile at 60 ° C. for 72 hours.

After working up according to Example 1, 0.755 g of copolymer (74.2% of theory) will hold egg. The following phase transformation points are determined by DSC: g 335 K s 371 K i

The elemental analysis gives the following composition:

C H N calculated 69.93% 7.24% 3.23% found 70.05% 7.30% 3.29%

Comparative example

2.2 g of methacryloyloxyhexyleneoxybenzoic acid p-methoxyanilide are dissolved in 35 ml of tetrahydrofuran and transferred into an ultrapure purged ampoule into which 0.02 g of azo-bis-isobutyronitrile has previously been weighed. The vessel is closed. In the thermostat, the polymerization and the subsequent work-up of the product takes place as described in Example 1. There are obtained 1.8 g of polymer, d.s. 81.8%, based on the monomer used. The product is chromatographically free of monomer. The elemental analysis of the resulting homopolymer is identical to that of the monomer compound used.

monomer homopolymer C 70.3% 70.3% H 7.23% 7.22% N 3.3% 3.32%

The DSC analysis shows that the poly-fmethacryloyloxyhexyleneoxybenzoic acid p-methoxyanilide has no liquid crystalline phase. The melting point is determined to be 127 ° C.

Claims (2)

claims: 1. A process for the preparation of novel liquid-crystalline copoly (Methäciyloyloxyalkylenoxybenzoesäure-p-alkoxyanilid-methacryloyloxyalkane) of the general formula I. CH. ² I co