Abstract: A process for the stabilization of the spatial alignment of the smectic layers in an FLC switching and/or display element, in which the original position of the smectic layers has been modified by electrical field treatment, which comprises alternately switching the elements during non-operation and/or when a certain temperature is exceeded which is above a predetermined temperature range which includes the operating temperature region and/or when the temperature falls below a certain temperature which is below a predetermined temperature range which includes the operating temperature region. Use of the process according to the invention ensures long-term functioning of the switching and display device, even in the case of repeated regeneration of the quasi-bookshelf geometry, and prevents worsening in the contrast and brightness and the occurrence of ghost images.

Abstract: Disclosed are derivatives of fluoroalkylethynyl- and difluoroalkylethynylbenzenes of the formula (I) herein. These compounds exhibit useful properties as liquid crystal compounds and are useful in nematic liquid crystal mixtures.

Abstract: A substrate for liquid-crystal displays is formed from polymers of polycyclic olefins by polymerization, without ring opening, of at least one monomer of the formula (I), (II), (III), (IV), (V) or (VI). The novel use of cycloolefin copolymers as substrate material facilitates process temperatures of above 180.degree. C. in the production of displays. Cycloolefin copolymers are lighter and less brittle than glass. Compared with other plastics, they have advantages in photoelastic constants, thermal expansion, hardness, density, transparency, water absorption and with respect to birefringence. Furthermore, they have high resistance to polar solvents.

Abstract: A 3,4,5-trifluorobenzene derivatives of formula (I): ##STR1## in which R.sup.1 is a straight-chain or branched alkyl having 1 to 15 carbon atoms in which one or two nonadjacent --CH.sub.2 --groups are optionally replaced by --O--, --CH.dbd.CH--, --C.tbd.C--, cyclopropane-1,2-diyl or --Si(CH.sub.3).sub.2 --, and in which one or more H atoms in the alkyl radical may be substituted by F; A.sup.1, A.sup.2 and A.sup.3 are identical or different 1,4-phenylene, pyridine-2,5-diyl, pyrimidine-2,5-diyl in which one or two H atoms are, optionally, replaced by F, trans-1,4-cyclohexylene, 1,3-dioxane-2,5-diyl or naphthalene-2,6-diyl,M.sup.1 and M.sup.2 are identical or different --CH.sub.2 CH.sub.2 --,--CH.dbd.CH--,--C.tbd.C--,--CH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2 --, --CH.sub.2 --O--,--O--CH.sub.2 --,--CO--O-- or--O--CO; X is --CH.sub.2 --O--,--OCH.sub.2 -- or --O--CO--; andk, l, m, n, o and p are zero or one provided that the sum k+m+o is greater than zero.

Abstract: 3-Chloropyridines, process for their preparation, and their use in liquid-crystal mixturesA 3-chloropyridine of the formula (I) ##STR1## in which the symbols have the following meaning: R.sup.1 and R.sup.2, independently of one another, are, for example, H or straight-chain or branched alkyl, A.sup.1, A.sup.2, A.sup.3 and A.sup.4 are identical or different and are, for example, 1,4-phenylene, pyrazine-2,5-diyl or trans-1,4-cyclohexylene, M.sup.1, M.sup.2, M.sup.3 and M.sup.4 are identical or different and are, for example, --O-- or --CO--O--, R.sup.3, R.sup.4, R.sup.6 and R.sup.7, independently of one another are, for example, H or straight-chain or branched alkyl, M.sup.5 is, for example, --O--CO-- or a single bond, k, l, m, n, o, p, q and r are zero or one, with the proviso that the sum k+m+p+r is less than 4 and greater than zero, can advantageously be employed as a component in ferroelectric liquid-crystal mixtures.

Abstract: An aromatic compound of the formula (I)R.sup.1 (--A.sup.1).sub.a (--M.sup.1).sub.b (--A.sup.2).sub.c (--M.sup.2).sub.d --B(--M.sup.3).sub.c (--A.sup.3).sub.f (--M.sup.4).sub.g (--A.sup.4).sub.h --R.sub.2 (I)in whichB is one of the two following aromatic groups: ##STR1## Q.sup.1, Q.sup.2, Q.sup.3 and Q.sup.4 are identical or different and are CH.sub.2, CF.sub.2, N--R.sup.3, S, O or C.dbd.O;P.sup.1, P.sup.2 and P.sup.3 are identical or different and are C--H, C--F or N; andthe remaining symbols and indicies define mesogenic radicals, The compounds are suitable as components of liquid-crystalline mixtures.

Abstract: The use of a compound of the formula I, in liquid crystal mixtures,R.sup.1 (--A.sup.1).sub.a (--M.sup.1).sub.b (--A.sup.2)--O--CF(CF.sub.3)--COO--(--A.sup.3)(--M.sup.2).sub.c (--A.sup.4).sub.d --R.sup.2 Iin which the symbols and indices have the following meanings:R.sup.1 and R.sup.2 are identical or different and are hydrogen, a straight-chain or branched alkyl radical having 1 to 20 carbon atoms (with or without asymmetrical carbon atoms), where one or more --CH.sub.2 -- groups may also be replaced by --O--, --CO--, cyclopropane-1,2-diyl, --Si(CH.sub.3).sub.2 --, with the proviso that oxygen atoms must not be bonded directly to one another, and/or one or more H atoms of the alkyl radical may be substituted by --F; M.sup.1 and M.sup.2 are identical or different and are --CO--O--, --O--CO--, or a single bond;A.sup.1, A.sup.2, A.sup.3 and A.sup.

Abstract: A smectic liquid-crystal mixture containing rod-shaped molecules having only one side chain and certain phenylpyrimidine derivatives. The liquid-crystal mixtures according to the invention are distinguished by a low melting point and a high S.sub.C /S.sub.A phase-transition temperature. The use of bisesters of the formula I allows the number of phenylpyrimidine derivatives in the mixtures according to the invention to be significantly reduced. Ferroelectric mixtures according to the invention have, in particular, high contrast, good alignment, a large margin, low flicker and a large angle in the chevron geometry.

Abstract: Meta-substituted aromatic compounds having six-membered rings, for use in liquid-crystal mixturesCompounds of the formula I ##STR1## in which X is CH, CF or N,R.sup.2 is, for example, an alkyl, ether or ester group, which may also contain a chiral center, andR.sup.1 (--A.sup.1).sub.a (--M.sup.1).sub.b (--A.sup.2).sub.c (--M.sup.2) .sub.d (--A.sub.3).sub.e (--M.sub.3).sub.f is a mesogenic radical,can advantageously be used as components of liquid-crystal mixtures, in particular ferroelectric liquid-crystal mixtures.The substances of the formula I have a particularly favorable effect on the optical switching angle and the critical pulse area of the mixtures.

Abstract: A smectic liquid-crystal mixture comprisingA. at least one compound of the formula (I) ##STR1## B. at least one compound of the formula (III) ##STR2## C. compounds of the formula (IV)R.sup.1 --O--CO--O--(--A.sup.1).sub.a (--M.sup.1).sub.b (--A.sup.2).sub.c (--M.sup.2).sub.d (--A.sup.3).sub.e (--O).sub.f --R.sup.2 (IV)in which:R.sup.1 and R.sup.2 are identical or different and are a straight-chain or branched alkyl group having 1 to 22 or 3 to 22 carbon atoms respectively,A.sup.1, A.sup.2 and A.sup.3 are identical or different and are 1,4-phenylene, where one or two H atoms may also be replaced by F, 2,5-pyrimidinediyl,and further smectogenic compounds and, if desired, dopants. The mixture exhibits a low melting point and a broad S.sub.c phase.

Abstract: Smectic liquid-crystal mixture A liquid-crystalline mixture comprises, inter aliaA. at least one compound of the formula I ##STR1## and/or at least one compound of the formula (II) ##STR2## B. at least one compound of the formula (III)R.sup.1 (-A.sup.1).sub.a (-M.sup.1).sub.b (-A.sup.2).sub.c (-M.sup.2).sub.d (-A.sup.3).sub.e (-M.sup.3).sub.f (-A.sup.4)-H (III)C. and at least one compound of the formula (IV) ##STR3##The mixture has a low melting point and a broad S.sub.c phase range.

Abstract: Modified polysugar as an alignment layer for liquid-crystal displaysAn alignment layer for liquid-crystal displays (LCDs) containsa) at least one oligomer/polymer of a 6-membered cyclic sugar unit all or some of whose free OH groups may be derivatized and which carries equatorial substituents in the 2-, 3- and 6-positions on the ring, andb) at least one compound from the group consisting of macrocyclic compounds, cryptands, coronands, podands, mercapto compounds and ionophores.LCDs which contain an alignment layer according to the invention are particularly distinguished by good contrast and bright-transmission values and by good alignment of the liquid crystal.