the dental materials are produced by mixing the monomers according to the invention with one or more polymerization initiators and optionally other non - liquid crystalline monomers and fillers . unfilled dental materials essentially contain one or more liquid crystalline monomers and an initiator . they are particularly suitable as adhesives or for preventive dentistry , for example as a constituent of enamelling systems , releasing fluoride or antimicrobial active ingredients , for the prevention of caries . suitable as non - liquid crystalline monomers for combining with the monomers according to the invention are in particular triethylene glycol dimethacrylate , tetraethylene glycol dimethacrylate , butanediol dimethacrylate , hexanediol dimethacrylate , decanediol dimethacrylate and / or dodecanediol dimethacrylate . the quantity of non - liquid crystalline monomers is selected such that the formation of mesophases is not prevented . dental materials which were obtained exclusively using liquid crystalline monomers are preferred . filled dental materials also contain one or more fillers . preferred fillers are disclosed in u . s . pat . no . 4 , 629 , 746 and u . s . patent application ser . no . 08 / 025 , 810 . they preferably have an average particle size in the range from 0 . 01 to 5 μm . filled dental materials are particularly suitable as filling material , inlay , veneer or onlay material , dental cement , facing material for crowns and bridges , material for artificial teeth or other materials for prosthetic and preservation dentistry . the filler content is preferably in the range from 1 to 85 % by wt . the dental materials according to the invention can be polymerized radically , ionically or using a combination of radical and ionic initiators , radical polymerization being preferred . depending on the type of initiator used , the dental material can be polymerized hot , cold or using light . the known peroxides such as dibenzoyl peroxide , dilauroyl peroxide , tert .- butyl peroctoate or tert .- butyl perbenzoate can be used as initiators for the hot polymerization . furthermore , 2 , 2 &# 39 ;- azoisobutyric acid nitrile ( aibn ), benzpinacol and 2 , 2 &# 39 ;- dialkyl benzpinacols are also suitable . benzophenone and its derivatives and benzoin and its derivatives for example can be used as initiators for the photopolymerization . other preferred photoinitiators are the α - diketones such as 9 , 10 - phenanthrenequinone , diacetyl , furil , anisil , 4 , 4 &# 39 ;- dichlorobenzil and 4 , 4 &# 39 ;- dialkoxybenzil . camphor quinone is used particularly preferably . furthermore , the group of the acyl phosphinoxides is also well suited for initiating the photopolymerization of liquid crystalline acrylate and methacrylate monomers . to accelerate the initiation , the photoinitiators are preferably used together with a reducing agent , particularly preferably with an amine , especially an aromatic amine . used as initiators for the cold polymerization are radical - supplying redox systems , for example benzoyl or lauroyl peroxide together with amines such as n , n - dimethyl - p - toluidine , n , n - dihydroxyethyl - p - toluidine or other structurally related amines . the combination of photoinitiators with various redox systems has proved successful particularly in the case of dental materials for the cementing of dental restorations , such as for example glass ceramic inlays , onlays , partial crowns and crowns . combinations of camphor quinone , benzoyl peroxide and amines such as for example n , n - dimethyl - p - toluidine and / or n , n - cyanoethyl ethylaniline are preferred . the concentration of the initiators is preferably in the range from 0 . 05 to 1 . 5 % by wt ., particularly preferably in the range from 0 . 2 to 0 . 8 % by wt ., relative to the weight of the monomer used . the invention is described in more detail below with reference to embodiments . 15 . 0 g ( 59 . 0 mmol ) diethyl - 2 , 5 - dihydroxyterephthalate , 20 . 0 ml ( 142 mmol ) 1 - bromohexane , 28 . 0 g ( 203 mmol ) k 2 co 3 and 200 mg nai in 100 ml acetone are heated under reflux for 66 hours . the initially yellow suspension becomes largely decolorized . the solvent is then distilled off and the residue is taken up in 400 ml ethyl acetate and 200 ml water . after removing the aqueous phase , the organic phase is washed three times with 80 ml 1 n naoh and three times with 100 ml water and then dried over na 2 so 4 . after distilling off the ethyl acetate , the residue is taken up in petroleum ether . at - 30 ° c ., colourless crystals form which are recrystallized again from petroleum ether . c 24 h 38 o 6 ( 422 . 56 ) calc . c 68 . 22 h 9 . 06 found c 68 . 27 h 9 . 01 a mixture of 8 . 91 g ( 135 mmol ) 85 % aqueous koh solution and 20 ml water is added to 16 . 3 g ( 38 . 57 mmol ) 2 , 5 - dihexoxyterephthalic acid diethyl ester in 20 ml ethanol and the whole is stirred for 2 hours at 90 ° c . the crude product precipitated by the dropwise addition of 12 . 5 ml conc . hcl with ice - cooling is filtered off , washed neutral with water and recrystallized from ethanol . 5 . 63 ml ( 65 . 5 mmol ) oxalyl chloride are added to a suspension of 2 . 0 g ( 5 . 46 mmol ) 2 , 5 - dihexoxyterephthalic acid in 15 . 0 ml abs . methylene chloride and the whole is stirred at 25 ° c . for 24 h . after removing the solvent and excess oxalyl chloride in a vacuum , the residual solid dichloride is taken up in 10 . 0 ml absol . thf . with ice - cooling and stirring , a solution of 18 . 02 g ( 163 . 8 mmol ) hydroquinone in 40 ml absol . thf is then added dropwise to the yellow solution , followed by 11 . 5 ml ( 82 . 1 mmol ) triethylamine . the mixture is then stirred for 5 h at 0 ° c . the reaction mixture is acidified by the dropwise addition of 80 ml 1n hcl with ice - cooling , and the thf is then largely distilled off under vacuum . after adding 250 ml water , the precipitating crude product is filtered off , washed three times with water ( 3 × 50 ml ), and recrystallized twice from methanol . c 32 h 38 o 8 ( 550 . 65 ) calc . c 69 . 80 h 6 . 96 found c 70 . 00 h 7 . 06 firstly 0 . 53 ml ( 5 . 46 mmol ) methacryloyl chloride , then 0 . 82 ml ( 5 . 86 mmol ) absol . triethylamine are added dropwise , with ice - cooling , to a suspension of 1 . 0 g ( 1 . 82 mmol ) 2 , 5 - dihexoxyterephthalic acid - di - 4 - hydroxyphenyl ester in 10 . 0 ml absol . methylene chloride and the whole is stirred at room temperature for 4 h . after removing the solvent in a vacuum , the residual residue is taken up in 20 ml ethyl acetate and the ammonium salt is filtered off . the filtrate is stirred vigorously with a solution of 2 . 0 g ( 18 . 7 mmol ) na 2 co 3 in 30 ml water for 2 h , then the organic phase is removed , washed twice with 50 ml 1n hcl and 30 ml water and dried over na 2 so 4 . after distilling off the solvent in a vacuum , the crude product is recrystallized once from methanol and once from petroleum ether . melting point : 75 to 78 ° c . ( phase transition from the crystalline phase to the liquid crystalline phase ); 78 to 96 ° c . ( cloudy melt ); above 96 ° c . ( clear melt ; phase transition from the liquid crystalline phase to the isotropic melt ); c 40 h 46 o 10 ( 686 . 80 ) calc . c 69 . 95 h 6 . 75 found c 69 . 89 h 6 . 85 1 h - nmr ( cdcl 3 , 400 mhz ); δ = 0 . 92 ( t , 6h , ch 2 ch 2 ch 3 ); 1 . 32 - 1 . 41 ( m , 8h , ch 2 ); 1 . 51 - 1 . 58 ( m , 4h , och 2 ch 2 ch 2 ); 1 . 85 - 1 . 92 ( m , 4h , och 2 ch 2 ); 2 . 12 ( ps , 6h ch 3 ); 4 . 14 ( t , 4h , och 2 ); 5 . 81 ( ps , 2h , alkene ); 6 . 40 ( ps , 2h , alkene ); 7 . 25 ; 7 . 32 ( pd , 4h , arco 2 cch , aromatic substance ; pd , 4h , ch 2 ═ c ( ch 3 ) co 2 cch , aromatic substance ); 7 . 61 ( s , 2h , aromatic substance ). ms ( 70 ev ): m / z = 686 [ m + ], 509 , 510 [ m + -- ch 2 ═ c ( ch 3 ) co 2 ( c 6 h 4 ) o ] 25 . 4 g ( 0 . 1 mol ) diethyl - 2 , 5 - dihydroxyterephthalate , 232 ml ( 1 . 5 mol ) 1 , 6 - dibromohexane , 130 g ( 0 . 94 mol ) k 2 co 3 and 200 mg nai in 200 ml acetone are heated under reflux for 12 hours . the initially yellow suspension decolorizes . after distilling off the solvent , 1200 ml diethyl ether are added to the reaction mixture and the whole is washed twice , each time with 200 ml water . the organic phase is then dried over na 2 so 4 and the solvent is distilled off . the colourless product which crystallized out after adding 250 ml petroleum ether at - 20 ° c . is recrystallized once from petroleum ether and twice from ethanol . c 24 h 36 br 2 o 6 ( 580 . 35 ): calc . c 49 . 67 h 6 . 25 found c 49 . 94 h 6 . 28 50 . 0 g ( 86 . 0 mmol ) diethyl - 2 , 5 - bis -( 6 - bromohexoxy ) terephthalate , 84 . 5 g ( 861 mmol ) potassium acetate and 4 . 4 g ( 11 mmol ) methyl trioctyl ammonium chloride ( aliquat 336 ®, tricaprylyl methyl ammonium chloride , fluka , cas 5137 . 55 . 3 ) in 500 ml absolute acetonitrile are heated under reflux in a nitrogen atmosphere for 48 hours . after distilling off the solvent , the reaction mixture is taken up in 1200 ml ethyl acetate and washed three times with water ( 3 × 300 ml ). the organic phase is dried over mgso 4 and the solvent is then distilled off . 1000 ml petroleum ether is added to the residual , oily residue and the product crystallizing out after 16 hours at - 20 ° c . is recrystallized from petroleum ether / ethyl acetate . c 28 h 42 o 10 ( 538 . 63 ) calc . c 62 . 44 h 7 . 86 found c 62 . 49 h 7 . 85 a solution of 25 . 0 g ( 379 mmol ) 85 % koh in 300 ml water is added to 40 . 0 g ( 74 . 3 mmol ) diethyl - 2 , 5 - bis -( 6 - acetoxyhexoxy ) terephthalate in 250 ml ethanol and the whole is heated under reflux for 1 . 5 hours . after distilling off approx . 150 ml ethanol , the reaction mixture is acidified by adding 40 . 0 g conc . hcl and stored at 2 ° c . for 20 hours for complete crystallization of the crude product . the colourless crude product is then filtered off , washed neutral with water and recrystallized from ethanol . c 28 h 30 o 8 ( 398 . 45 ): calc . c 60 . 29 h 7 . 59 found c 60 . 45 h 7 . 46 38 . 9 ml ( 405 mmol ) methacryloyl chloride and 56 . 7 ml ( 405 mmol ) triethylamine are added , with stirring , to a mixture of 27 . 0 g ( 67 . 8 mmol ) 2 , 5 - bis -( 6 - hydroxyhexoxy )- terephthalic acid and 20 mg hydroquinone monopropyl ether in 400 ml absolute thf and the whole is then stirred for a further 24 hours . after distilling off approx . 250 ml solvent , 28 . 6 g ( 270 mmol ) na 2 co 3 in 150 ml water are added and stirring is continued for 48 hours at room temperature . the suspension is acidified by adding 50 ml conc . hcl and 200 ml water . the organic phase is removed and washed three times with water and then dried over na 2 so 4 . after adding 50 mg hydroquinone monopropylether and 10 g activated charcoal , the mixture is stirred for 30 minutes under slight reflux . the activated charcoal is then filtered off and the solvent is removed by distillation . 300 ml diethyl ether are added to the residue . after 24 hours at - 26 ° c ., yellow crystals form which are recrystallized again from diethyl ether / ethyl acetate . c 28 h 38 o 10 ( 534 . 60 ): calc . c 62 . 91 h 7 . 16 found c 62 . 79 h 7 . 35 15 . 0 ml ( 175 mmol ) oxalyl chloride are added under reflux to 5 . 00 g ( 9 . 35 mmol ) 2 , 5 - bis -[ 6 -( oxymethacryloyl ) hexoxy ] terephthalic acid and 10 mg hydroquinone monopropyl ether in 30 ml absolute methylene chloride . the mixture is stirred for a further 72 hours and the solvent is distilled off in vacuum at 50 ° c . to the oily residue is added dropwise , with stirring , a solution of 7 . 23 g ( 18 . 7 mmol ) cholesterol in 10 ml absolute thf and then , with ice - cooling , 3 . 0 ml triethylamine . after adding 10 mg hydroquinone monopropylether , the mixture is then stirred for 6 days at room temperature , then the solvent is distilled off and the residue taken up in 200 ml diethyl ether . the organic phase is washed three times with water ( 3 × 50 ml ), and then dried over na 2 so 4 . after distilling off the solvent , a brownish , oily crude product is obtained which is recrystallized firstly from ethyl acetate / isopropanol and then from thf / ethanol . ir ( kbr ): 3010 - 2820 ( c -- h ), 1715 ( c ═ o ; terephthalate ), 1705 ( c ═ o ; methacrylate ), 1635 ( c ═ c ; alkene ), 1495 cm - 1 ( c ═ c ; aromatic substance ). 1 h - nmr ( cdcl 3 , 400 mhz ): δ = 0 . 69 - 2 . 04 ( 82h , aliph . h , cholesterol structure ; 16h , ch 2 , spacer ), 1 . 94 ( ps , 6h , ch 2 ═ c -- ch 3 ), 2 . 46 ( m , 4h , co 2 chch 2 -- c ═ ch --, cholesterol structure ), 4 . 00 ( t , 4h , aroch 2 --), 4 . 15 ( t , 4h , co 2 ch 2 --), 4 . 86 ( m , 2h , arco 2 ch ), 5 . 42 ( m , 2h , alkene , cholesterol structure ), 5 . 53 ( ps , 2h , ch 2 ═ c -- ch 3 ), 6 . 09 ( ps , 2h , ch 2 ═ c -- ch 3 ), 7 . 30 ( s , 2h , aromatic substance ). c 82 h 126 o 10 ( 1271 . 89 ): calc . c 77 . 44 h 9 . 99 found c 77 . 32 h 10 . 01 25 . 4 g ( 0 . 1 mol ) diethyl - 2 , 5 - dihydroxyterephthalate , 450 g ( 1 . 5 mol ) 1 , 10 - dibromodecane , 138 g ( 1 . 0 mol ) k 2 co 3 and 200 mg nai in 200 ml acetone are heated under reflux for 28 hours until the originally yellow suspension has decolorized . after distilling off the solvent , the reaction mixture is extracted twice with diethyl ether ( 2 × 250 ml ), and insoluble salts are filtered off . the filtrate is washed twice with 200 ml water and dried over na 2 so 4 . the solvent is then distilled off . the colourless , solid residue is washed twice with petroleum ether and then recrystallized from petroleum ether . c 32 h 52 br 2 o 6 ( 692 . 56 ) calc . c 55 . 50 h 7 . 57 found c 55 . 78 h 7 . 58 46 . 4 g ( 67 . 0 mmol ) diethyl - 2 , 5 - bis -( 10 - bromodecoxy ) terephthalate , 65 . 8 g ( 671 mmol ) potassium acetate and 3 . 4 g ( 8 . 5 mmol ) aliquat 336 ® in 350 ml absolute acetonitrile are heated under n 2 under reflux for 48 hours . after distilling off the solvent , the reaction mixture is taken up in 300 ml chloroform , insoluble salts are filtered off and the filtrate is washed twice with 150 ml water . the organic phase is dried over na 2 so 4 and the solvent is then distilled off . 300 ml petroleum ether are added to the remaining , oily residue , the product crystallising out after 16 hours at - 20 ° c . it is then recrystallized from ethanol . c 36 h 58 o 10 ( 650 . 85 ) calc . c 66 . 44 h 8 . 98 found c 66 . 45 h 9 . 20 a solution of 20 . 0 g ( 303 mmol ) 85 % aqueous koh in 200 ml water is added to 38 . 0 g ( 58 . 4 mmol ) diethyl - 2 , 5 - bis -( 10 - acetoxydecoxy ) terephthalate in 200 ml ethanol and the whole is heated under reflux for 1 . 5 hours . 28 . 0 ml conc . hcl are then added dropwise with ice - cooling and stirring until the solution shows an acidic ph . the precipitated , colourless crude product is filtered off , washed neutral and recrystallized from ethanol and methanol / acetone . c 28 h 46 o 8 ( 510 . 66 ) calc . c 65 . 86 h 9 . 08 found c 65 . 62 h 9 . 30 30 . 0 ml ( 311 mmol ) methacroyl chloride and 43 . 8 ml ( 313 mmol ) triethylamine are added , with stirring at 0 ° c ., to a mixture of 15 . 0 g ( 29 . 4 mmol ) 2 , 5 - bis -( 10 - hydroxydecoxy ) terephthalic acid and 20 mg hydroquinone monopropyl ether in 150 ml abs . thf , and the whole is then stirred for a further 48 hours at 40 ° c . after distilling off approx . 75 ml of the solvent , 25 . 0 g ( 236 mmol ) na 2 co 3 in 200 ml water are added to the reaction mixture and the mixture is stirred for 48 hours at room temperature . the suspension is acidified by adding 120 ml semi - conc . hcl and 200 ml water at 0 ° c . after removing the aqueous phase , the residual oily crude product is taken up in 100 ml methanol and water is added dropwise with stirring . the precipitated product is filtered off and then recrystallized , once from ethanol and once from ethyl acetate . melting point : 72 to 74 ° c ., up to 116 ° c . the melt remains cloudy , above this , a clear melt exists . c 36 h 54 o 10 ( 646 . 82 ): calc . c 66 . 85 h 8 . 42 found c 66 . 71 h 8 . 51 6 . 66 ml ( 77 . 3 mmol ) oxalyl chloride are added dropwise , at 0 ° c . with stirring , to a solution of 5 . 00 g ( 7 . 73 mmol ) 2 , 5 - bis -[ 10 -( oxymethacroyl )- decoxy ] terephthalic acid in 20 ml abs . methylene chloride . the mixture is stirred for a further 24 hours and then the solvent and excess oxalyl chloride are distilled off in a high vacuum at room temperature . the residue is taken up with 15 ml abs . thf and a solution of 15 . 0 g ( 38 . 75 mmol ) cholesterol in 20 ml abs . thf and then 7 . 0 ml triethylamine are added dropwise with stirring . after adding 10 mg hydroquinone monopropyl ether , the mixture is stirred for 120 hours at 45 ° c ., the solvent is distilled off , the yellow residue is extracted with a total of 400 ml diethyl ether and undissolved ammonium salt is filtered off . the filtrate is concentrated in a vacuum to a volume of approx . 50 ml and 300 ml methanol are added with stirring . the obtained oily crude product is washed several times with methanol and then purified by means of column chromatography . an oily product is obtained which clearly becomes more thinly liquid at a temperature of 70 ° c . or more . ir ( kbr ): 2950 - 2830 ( c -- h ), 1715 ( c ═ o ; terephthalate ), 1695 ( c ═ o ; methacrylate ), 1635 ( c ═ c ; alkene ), 1500 cm - 1 ( c ═ c ; aromatic substance ). 1 h - nmr ( cdcl 3 , 400 mhz ): δ = 0 . 73 - 2 . 08 ( 82h , aliph . h , cholesterol structure ; 32h , ch 2 , spacer ); 1 . 98 ( ps . 6h , ch 2 ═ c -- ch 3 ); 2 . 50 ( m , 4h , co 2 chch 2 -- c ═ ch --, cholesterol structure ); 4 . 02 ( t , 4h , aroch 2 --); 4 . 17 ( t , 4h , co 2 ch 2 --); 4 . 90 ( m , 2h , arco 2 ch ); 5 . 45 ( m , 2h , alkene , cholesterol structure ); 5 . 57 ( ps , 2h , ch 2 ═ c -- ch 3 ); 6 . 13 ( ps , 2h , ch 2 ═ c -- ch 3 ); 7 . 33 ( s , 2h , aromatic substance ). c 82 h 126 o 10 ( 1384 . 11 ) calc . c 78 . 10 h 10 . 34 found c 78 . 09 h 10 . 41 determination of the polymerization shrinkage of 2 , 5 - bis -[ 10 -( oxymethacryloyl ) decoxy ] terephthalic acid dicholesteryl ester ( fig4 iib ) 0 . 3 % camphor quinone and 0 . 5 % n - 2 - cyanoethyl - n - methylaniline at 50 ° c . are added to 2 , 5 - bis -[ 10 - oxymethacryloyl ) decoxy ] terephthalic acid dicholesteryl ester and the whole is homogeneously mixed . after cooling to room temperature , the mixture was polymerized 2 × 3 minutes in a spectramat ( dental light polymerization device from ivoclar ). subsequent determination of the polymerization shrinkage gave a value of only 1 . 32 % by vol . parallel to this , a sample of bis - gma was polymerized as described above . the polymerization shrinkage was 6 . 0 % by vol . production of a dental material based on 2 , 5 - bis -[ 10 -( oxymethacryloyl ) decoxy ] terephthalic acid dicholesteryl ester ( fig4 iib ) a composite securing cement based on a non - liquid crystalline monomer ( decanediol methacrylate ) and a liquid crystalline monomer ( 2 , 5 - bis -[ 10 -( oxymethacryloyl ) decoxy ] terephthalic acid dicholesteryl ester ) was produced according to table 1 . the material properties of the securing cements were then determined . as is clear from table 2 , the conventional dental material has a polymerization shrinkage almost twice as great as the material according to the invention . the mechanical properties of the hardened cements are comparable . table 1______________________________________ convent . cement &# 34 ; liquid crystalline &# 34 ; content cement content raw material (% by wt .) (% by wt . ) ______________________________________rm - 3 ( urethanedimethacrylate ) 31 . 60 32 . 90 decanediol dimethacrylate 7 . 80 -- 2 , 5 - bis -[ 10 -( oxymethacryl - -- 8 . 12 oyl ) decoxy ] terephthalic acid dicholesteryl ester aerosil ox - 50 silanized 41 . 42 39 . 01 ytterbium trifluoride 18 . 70 19 . 47 camphor quinone 0 . 24 0 . 25 n , n - diethyl - 3 , 5 - di - tert .- 0 . 23 0 . 24 butylaniline 3 , 5 - di - tert .- butyl - 4 - 0 . 01 0 . 01 hydroxytoluene ( bht ) ______________________________________ table 2______________________________________ &# 34 ; liquid crystalline &# 34 ; material property * convent . cement cement______________________________________polymerization shrinkage 4 . 86 % by vol . 2 . 80 % by vol . flexural strength according 86 mpa 79 . 5 mpa to iso 4049 flexural modulus according 3 . 19 gpa 4 . 09 gpa to iso 4049______________________________________ * testpiece was hardened by 2 × 3 minutes irradiation in the spectramat