Process for controlling layer spacing in mixtures of smectic liquid crystal compounds

Claim 2

A process for controlling layer spacing comprising the step of combining a liquid crystal composition having a net negative thermal layer expansion in at least one tilted or latent tilted smectic mesophase and a liquid crystal composition having a net positive thermal layer expansion in at least one tilted or latent tilted smectic mesophase, each of said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, so as to form a mixture of liquid crystal compounds having a controllable layer expansion or contraction behavior.

Claim 3

The process of claim 1 wherein said composition having a net negative thermal layer expansion is utilized in an amount such that the resulting combination has an essentially temperature-independent layer spacing in at least one tilted smectic mesophase.

Claim 4

A process for controlling layer spacing comprising the step of combining a liquid crystal composition having a net negative thermal layer expansion in at least one tilted or latent tilted smectic mesophase and a liquid crystal composition having a net positive thermal layer expansion in at least one tilted or latent tilted smectic mesophase, each of said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, wherein said composition having a net negative thermal layer expansion is utilized in an amount such that the resulting combination has a net thermal layer expansion in at least one tilted smectic mesophase within the range of from about -0.05 to about +0.05 Å/°C.

Claim 5

A process for controlling layer spacing comprising the step of combining a liquid crystal composition having a net negative thermal layer expansion in at least one tilted or latent tilted smectic mesophase and a liquid crystal composition having a net positive thermal layer expansion in at least one tilted or latent tilted smectic mesophase, each of said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, wherein said composition having a net negative thermal layer expansion is utilized in an amount such that the resulting combination has a net thermal layer expansion in at least one tilted smectic mesophase within the range of from about -0.05 to about +0.05 Å/°C.

Claim 6

The process of claim 3 wherein said range is from about -0.01 to about +0.01 Å/°C.

Claim 7

The process of claim 4 wherein said range is from about -0.005 to about +0.005 Å/°C.

Claim 8

The process of claim 1 wherein said composition having a net negative thermal layer expansion comprises at least one chiral or achiral liquid crystal compound having at least one fluorinated terminal portion.

Claim 9

The process of claim 6 wherein said compound has at least one fluoroether terminal portion containing at least two catenary ether oxygen atoms.

Claim 10

The process of claim 7 wherein said compound comprises (a) an aliphatic fluorocarbon terminal portion containing at least two catenary ether oxygen atoms; (b) an aliphatic hydrocarbon terminal portion; and (c) a central core connecting said terminal portions.

Claim 11

The process of claim 8 wherein said aliphatic fluorocarbon terminal portion is represented by the formula --D(C x F 2x O) z C y F 2y+1 , where x is independently an integer of 1 to about 12 for each C x F 2x O group, y is an integer of 1 to about 12, z is an integer of 2 to about 10, and D is selected from the group consisting of a covalent bond, ##STR48## --O--C r H 2r --, --O--C s H 2s O-- t C r' H 2r' --, --C r H 2r --, --C s H 2s O-- t C r' H 2r' --, --OSO 2 --, --SO 2 --, --SO 2 --C r H 2r --, ##STR49## --C.tbd.C--, --CH═CH--, ##STR50## --CH═N--, --O--, --S--, --N(C p H 2p+1 )--, and combinations thereof, where r and r' are independently integers of 0 to about 20, s is independently an integer of 1 to about 10 for each (C s H 2s O), t is an integer of 1 to about 6, and p is an integer of 0 to about 4.

Claim 12

The process of claim 8 wherein said compound is represented by the general formula I: ##STR51## where M, N, and P are each independently selected from the group consisting of ##STR52## a, b, and c are each independently zero or an integer of from 1 to 3, with the proviso that the sum of a+b+c be at least 1; each A and B are non-directionally and independently selected from the group consisting of a covalent bond, ##STR53## --(CH 2 CH 2 ) k -- where k is 1 to 4, --CH═CH--, --C.tbd.C--, --CH═N--, --CH 2 --O--, ##STR54## and --O--; each X, Y, and Z are independently selected from the group consisting of --H, --Cl, --F, --Br, --I, --OH, --OCH 3 , --CH 3 , --CF 3 , --OCF 3 --CN, and --NO 2 ; each l, m, and n are independently zero or an integer of 1 to 4; D is selected from the group consisting of a covalent bond, ##STR55## --O--C r H 2r --, ##STR56## --C.tbd.C--, --CH═CH--, ##STR57## --O--C s H 2s O-- t C r' H 2r' --, --C r H 2r --, --C s H 2s O-- t C r' H 2r' --, --O--, --S--, --OSO 2 --, --SO 2 --, --SO 2 --C r H 2r --, ##STR58## --N(C p H 2p+1 )--, ##STR59## --CH═N--, and combinations thereof, where r and r' are independently integers of 0 to about 20, s is independently an integer of 1 to about 10 for each (C s H 2s O), t is an integer of 1 to about 6, and p is an integer of 0 to about 4; R is selected from the group consisting of --O--((C q' H 2q'-v' --(R') v' )--O) w --C q H 2q+1-v --(R') v , --((C q' H 2q'v' --(R') v' )--O) w --C q H 2q+1-v --(R') v , ##STR60## and --CR'H--(D) g' --CR'H--, where each R' is independently selected from the group consisting of --Cl, --F, --CF 3 , --NO 2 , --CN, --H , --C q H 2q+1 , ##STR61## where q' is independently an integer of 1 to about 20 for each (C q' H 2q' --O--), q is an integer of 1 to about 20, w is an integer of 0 to about 10, v is an integer of 0 to about 6, each v' is independently an integer of 0 to about 6, g is an integer of 1 to about 3, g' is an integer of 1 to about 3, each D is independently selected from the group set forth above, and R is linear or branched and chiral or achiral; and R f is --(C x F 2x O) z C y F 2y+1 , where x is independently an integer of 1 to about 12 for each (C x F 2x O), y is an integer of 1 to about 12, and z is an integer of 2 to about 10.

Claim 13

The process of claim 10 wherein said compound is represented by the formula: ##STR62## where x is independently an integer of 1 to about 8 for each C x F 2x O; y is an integer of 1 to about 8; z is an integer of 2 to about 4; j is an integer of 0 or 1; j' is an integer of 0 or 1; and R" is selected from the group consisting of (R') v --C q H 2q+1-v and ##STR63## where each q is independently an integer of 2 to about 10; each R' is independently selected from the group consisting of hydrogen, fluorine, chlorine, methyl, and perfluoromethyl; v is an integer of 0 to about 4; and C q H 2q and C q H 2q+1 are linear or branched.

Claim 14

The process of claim 6 wherein said compound has at least one fluoroaliphatic terminal portion.

Claim 15

The process of claim 12 wherein said compound is 5-hexyl-2-(4'-1,1-dihydroperfluorooctyloxy)phenylpyrimidine.

Claim 16

The process of claim 1 wherein said composition having a net positive thermal layer expansion comprises at least one chiral or achiral liquid crystal compound having terminal portions independently selected from the group consisting of aliphatic terminal portions, fluoroaliphatic terminal portions, and fluoroether terminal portions containing one catenary ether oxygen atom.

Claim 17

The process of claim 8 wherein said compound is the major component of said composition having a net negative thermal layer expansion, and wherein said composition having a net positive thermal layer expansion comprises as the major component at least one chiral or achiral liquid crystal compound having a terminal portion selected from the group consisting of fluoroaliphatic terminal portions and fluoroether terminal portions containing one catenary ether oxygen atom.

Claim 18

The process of claim 15 wherein said terminal portion is a fluoroether terminal portion containing one catenary ether oxygen atom.

Claim 19

A process for controlling layer spacing comprising the step of combining a liquid crystal composition having a net negative thermal layer expansion of known magnitude in at least one tilted or latent tilted smectic mesophase and a liquid crystal composition having a net positive thermal layer expansion of known magnitude in at least one tilted or latent tilted smectic mesophase, said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, and said compositions being utilized in amounts based upon said magnitudes such that the resulting combination has a desired net thermal layer expansion in at least one tilted smectic mesophase.

Claim 20

A process for controlling layer spacing comprising the step of combining a liquid crystal composition having a net negative thermal layer expansion of known magnitude in at least one tilted or latent tilted smectic mesophase and a liquid crystal composition having a net positive thermal layer expansion of known magnitude in at least one tilted or latent tilted smectic mesophase, said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, and said compositions being utilized in amounts based upon said magnitudes such that the resulting combination has a desired net thermal layer expansion in at least one tilted smectic mesophase.

Claim 21

A mixture of liquid crystal compounds prepared by the process of claim 1.

Claim 22

A mixture of liquid crystal compounds comprising a liquid crystal composition having a net negative thermal layer expansion in at least one tilted or latent tilted smectic mesophase and a liquid crystal composition having a net positive thermal layer expansion in at least one tilted or latent tilted smectic mesophase, each of said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, wherein said composition having a net negative thermal layer expansion is present in an amount such that said mixture has a net thermal layer expansion in at least one tilted smectic mesophase within the range of from about -0.05 to about +0.05 Å/°C.

Claim 23

A mixture of liquid crystal compounds comprising a liquid crystal composition having a net negative thermal layer expansion in at least one tilted or latent tilted smectic mesophase and a liquid crystal composition having a net positive thermal layer expansion in at least one tilted or latent tilted smectic mesophase, each of said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, wherein said composition having a net negative thermal layer expansion is present in an amount such that said mixture has a net thermal layer expansion in at least one tilted smectic mesophase within the range of from about -0.05 to about +0.05 Å/°C.

Claim 24

The mixture of claim 19 wherein said range is from about -0.01 to about +0.01 Å/°C.

Claim 25

The mixture of claim 20 wherein said range is from about -0.005 to about +0.005 Å/°C.

Claim 26

A liquid crystal display device containing the mixture of claim 18.

Claim 27

A liquid crystal display device containing the mixture of claim 19.

Claim 28

A process for controlling layer spacing comprising the step of combining a liquid crystal composition having a net negative thermal layer expansion in the smectic C mesophase, said composition comprising at least one chiral or achiral, smectic or latent smectic liquid crystal compound having a fluoroether terminal portion containing at least two catenary ether oxygen atoms; and a liquid crystal composition having a net positive thermal layer expansion in the smectic C mesophase, said composition comprising at least one chiral or achiral, smectic or latent smectic liquid crystal compound having a terminal portion selected from the group consisting of fluoroaliphatic terminal portions and fluoroether terminal portions containing one catenary ether oxygen atom; wherein said composition having a net negative thermal layer expansion is utilized in an amount such that the resulting combination has a net thermal layer expansion in the smectic C mesophase within the range of from about -0.05 to about +0.05 Å/°C.

Claim 29

A process for controlling layer spacing comprising the step of combining a liquid crystal composition having a net negative thermal layer expansion in the smectic C mesophase, said composition comprising at least one chiral or achiral, smectic or latent smectic liquid crystal compound having a fluoroether terminal portion containing at least two catenary ether oxygen atoms; and a liquid crystal composition having a net positive thermal layer expansion in the smectic C mesophase, said composition comprising at least one chiral or achiral, smectic or latent smectic liquid crystal compound having a terminal portion selected from the group consisting of fluoroaliphatic terminal portions and fluoroether terminal portions containing one catenary ether oxygen atom; wherein said composition having a net negative thermal layer expansion is utilized in an amount such that the resulting combination has a net thermal layer expansion in the smectic C mesophase within the range of from about -0.05 to about +0.05 Å/°C.

Claim 30

The process of claim 1 wherein said smectic mesophase is the smectic C mesophase.

Claim 31

A process for controlling layer spacing comprising the step of combining at least two liquid crystal compositions having net thermal layer expansions of the same sign and known magnitudes in at least one tilted or latent tilted smectic mesophase, said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, and said compositions being utilized in amounts based upon said magnitudes such that the resulting mixture of liquid crystal compounds has a desired net thermal layer expansion in at least one tilted smectic mesophase.

Claim 32

A process for controlling layer spacing comprising the step of combining at least two liquid crystal compositions having net thermal layer expansions of the same sign and known magnitudes in at least one tilted or latent tilted smectic mesophase, said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, and said compositions being utilized in amounts based upon said magnitudes such that the resulting mixture of liquid crystal compounds has a desired net thermal layer expansion in at least one tilted smectic mesophase.

Claim 33

The process of claim 26 wherein said desired net thermal layer expansion is within the range of from about -0.05 to about +0.05 Å/°C.

Claim 34

The process of claim 26 wherein said smectic mesophase is the smectic C mesophase.

Claim 35

A mixture of liquid crystal compounds prepared by the process of claim 26.

Claim 36

A mixture of liquid crystal compounds comprising at least two liquid crystal compositions having net thermal layer expansions of the same sign in at least one tilted or latent tilted smectic mesophase, each of said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, wherein each of said compositions is present in an amount such that said mixture has a net thermal layer expansion in at least one tilted smectic mesophase within the range of from about -0.05 to about +0.025 Å/°C.

Claim 37

A mixture of liquid crystal compounds comprising at least two liquid crystal compositions having net thermal layer expansions of the same sign in at least one tilted or latent tilted smectic mesophase, each of said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, wherein each of said compositions is present in an amount such that said mixture has a net thermal layer expansion in at least one tilted smectic mesophase within the range of from about -0.05 to about +0.025 Å/°C.

Claim 38

A liquid crystal display device containing the mixture of claim 29.

Claim 39

A liquid crystal display device containing the mixture of claim 30.

Claim 40

A process for estimating the net thermal layer expansion of a latent smectic liquid crystal composition in at least one latent tilted smectic mesophase comprising the steps of (a) preparing at least one mixture of a latent smectic liquid crystal composition and a smectic liquid crystal composition, said latent smectic liquid crystal composition comprising at least one latent smectic liquid crystal compound and said smectic liquid crystal composition comprising at least one smectic liquid crystal compound; (b) determining the net thermal layer expansion of said mixture in at least one selected tilted smectic mesophase; (c) determining the net thermal layer expansion of said smectic liquid crystal composition in at least one corresponding tilted smectic mesophase; and (d) extrapolating to a composition of 100 percent said latent smectic liquid crystal composition to obtain an approximate value of the net thermal layer expansion for said latent smectic liquid crystal composition in at least one corresponding latent tilted smectic mesophase.

Claim 41

A process for estimating the net thermal layer expansion of a latent smectic liquid crystal composition in at least one latent tilted smectic mesophase comprising the steps of (a) preparing at least one mixture of a latent smectic liquid crystal composition and a smectic liquid crystal composition, said latent smectic liquid crystal composition comprising at least one latent smectic liquid crystal compound and said smectic liquid crystal composition comprising at least one smectic liquid crystal compound; (b) determining the net thermal layer expansion of said mixture in at least one selected tilted smectic mesophase; (c) determining the net thermal layer expansion of said smectic liquid crystal composition in at least one corresponding tilted smectic mesophase; and (d) extrapolating to a composition of 100 percent said latent smectic liquid crystal composition to obtain an approximate value of the net thermal layer expansion for said latent smectic liquid crystal composition in at least one corresponding latent tilted smectic mesophase.

Claim 42

The process of claim 33 wherein said smectic mesophase is the smectic C mesophase.

Claim 43

A liquid crystal display device containing a mixture of liquid crystal compounds comprising a liquid crystal composition having a net negative thermal layer expansion in at least one tilted or latent tilted smectic mesophase and a liquid crystal composition having a net positive thermal layer expansion in at least one tilted or latent tilted smectic mesophase, each of said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, wherein said composition having a net negative thermal layer expansion is present in an amount such that said mixture has an essentially temperature-independent layer spacing in at least one tilted smectic mesophase.

Claim 44

A liquid crystal display device containing a mixture of liquid crystal compounds comprising a liquid crystal composition having a net negative thermal layer expansion in at least one tilted or latent tilted smectic mesophase and a liquid crystal composition having a net positive thermal layer expansion in at least one tilted or latent tilted smectic mesophase, each of said compositions comprising at least one liquid crystal compound selected from the group consisting of smectic liquid crystal compounds and latent smectic liquid crystal compounds, wherein said composition having a net negative thermal layer expansion is present in an amount such that said mixture has an essentially temperature-independent layer spacing in at least one tilted smectic mesophase.

Claim 45

The device of claim 35 wherein said composition having a net negative thermal layer expansion comprises at least one chiral or achiral liquid crystal compound having at least one fluorinated terminal portion.

Claim 46

The device of claim 35 wherein said smectic mesophase is the smectic C mesophase.