Thermotropic polymers with lateral chains having a chiral structure and process and their manufacture

The invention concerns a family of thermotropic polymers of the mesogenic the lateral group of which have at least one mesomorphous phase and obtained from a monomer having the general formula: ##STR1## in which R.sub.1 .dbd.CH.sub.3, Cl or H and 2.ltoreq.n.ltoreq.11.

BACKGROUND OF THE INVENTION 
1. Field of the invention 
The present invention concerns a novel family of thermotropic polymers the 
lateral chains of which have a chiral structure. The family of compounds 
according to the invention is formed from a monomer having the general 
chemical formula: 
EQU CH.sub.2 =C(R.sub.1)--COO--(CH.sub.2).sub.n --OR.sub.2 
in which: 
R.sub.1 is the methyl radical or an hydrogen or chlorine atom, 
n is an integer comprised between 2 and 11; and 
R.sub.2 is the group 
##STR2## 
The invention also concerns the process for manufacturing molecules of this 
family. 
2. Description of the prior art 
After the extraordinary development of research upon liquid crystals over 
the past fifteen years, due mainly to their potential practical 
utilization (their simplicity in ease of use low control tensions, low 
consumption) many research teams have directed their efforts towards 
research on mesomorphous polymers. Thermotropic mesomorphous polymers are 
macromolecules presenting, over a certain range of temperatures often 
relatively high, anisotropic phases called smectic or nematic phases. They 
comprise one class of polymers with mesogenic lateral groups and another 
class where the mesogenic group is comprised within the chain. The present 
invention concerns a family of polymers belonging to the first class 
specified above. 
Although liquid crystals of low molecular weight crystallize at low 
temperature, the majority of thermotropic polymers with lateral chains are 
amorphous and are characterized by their vitreous transition temperature 
Tg. Both the macroscopic texture and the mesophasic range parameter can be 
frozen in the vitreous state. 
Thereby, it is possible to obtain films having anisotropic optical 
properties that can be utilized in devices of the non-linear optical 
field. 
Furthermore, the study of cholesteric phases allow to envisage the 
preparation of filters, reflectors and force measuring apparatus. In fact, 
it is possible to obtain, among others, through the intermediary of 
materials according to the invention, cholesteric thermotropic polymers. 
Furthermore, since the threshold tension values and the time intervals 
required for the orientation of the mesophases placed within an electrical 
field are of the same dimensions as those of the liquid crystals of low 
molecular weight, it is possible to consider that these polymers could be 
utilized in visualization devices intended for data memory storage. 
SUMMARY OF THE INVENTION 
The aim of the present invention is therefore a thermotropic polymer of the 
mesogenic lateral group type, presenting at least one mesomorphous phase, 
said polymer being obtained through polymerization of at least one monomer 
M.sub.1 having the general chemical formula: 
##STR3## 
in which: R.sub.1 =CH.sub.3, Cl or H and 2.ltoreq.n.ltoreq.11. 
Another aim of the present invention is a process for manufacturing such an 
organic compound, comprising the following steps: 
first step: synthesis of 2-methyl-1-bromobutane through the action of 
phosphorous tribromide upon 2-methyl-1-butanol; 
second step: synthesis of 4(3-methylbutyloxyphenol) through reaction of the 
2-methyl-1-bromobutane obtained in the first step on hydroquinone; 
third step: synthesis of para-hydroxy-methyl-benzoic acid salt through 
esterification of 4-hydroxy-benzoic acid; 
fourth step: synthesis of para(hydroxyalkyloxy)-methyl-benzoic acid salt 
through reaction of w-bromoalcanol upon the parahydroxy-methyl-benzoic 
acid salt obtained in the third step: 
fifth step: synthesis of para(hydroxyalkyloxy)-benzoic acid through 
saponification of the ester obtained in the fourth step; 
sixth step: synthesis of 4(methacrylyloxy)alkoxy-benzoic acid, of 
4(acrylyloxy)alkyloxy-benzoic acid or of 
4(.alpha.-chloroacrylyloxy)alkoyloxy-benzoic acid through azeotropic 
esterification of the acid obtained in the fifth step with the 
methacrylic, acrylic or .alpha.-chloroacrylic acid respectively; 
seventh step: chloruration of the acid obtained in the sixth step; 
eighth step: synthesis of the monomer M.sub.1 through reaction of the acid 
chloride obtained in the seventh step and of the alkoxyphenol obtained in 
the second step; and 
ninth step: polymerization of the monomer M.sub.1 alone or in the presence 
of at least one other monomer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The following description concerns the general synthesis process of 
molecules according to the invention as well as the mesomorphous 
properties of the corresponding thermotropic polymers. Furthermore, 
potential application examples will also be given. 
GENERAL SYNTHESIS PROCESS 
The compounds according to the invention are obtained in nine steps from 
the following commercially available products: 2-methyl-1-butanol, 
4-hydroxy-benzoic acid and a .omega.-bromoalcanol. 
Reaction 1: obtention of 2-methyl-1-bromobutane 
This bromated derivate is obtained through the reaction of phosphor 
tribromide with 2-methyl-1-butanol in the presence of pyridine at a 
temperature of 10.degree. C. 
##STR4## 
Reaction 2: obtention of 4(3-methylbutyloxyphenol) 
4(3-methylbutyloxyphenol) is obtained through reaction of 
2-methyl-1-bromobutane, obtained upon completion of reaction 1, with 
hydroquinone in the presence of a potassium hydroxide alcohol solution. 
##STR5## 
Reaction 3: obtention of para-hydroxy-methyl-benzoic acid salt 
This derivate is obtained through the conventional esterification method of 
4-hydroxy-benzoic acid described by RIEGEL, MOFFET and McINTOSH in Organic 
Syntheses, vol. 3, p. 327. The reaction is carried out through reaction of 
acetyl chloride in the presence of methanol. 
##STR6## 
Reaction 4: preparation of para(hydroxyalkyloxy)methyl-benzoic acid salt 
This derivate is obtained through reaction of .omega.-bromoalcanol upon the 
parahydroxy-methyl-benzoic acid salt obtained upon completion of reaction 
3, in the presence of a potassium hydroxide alcohol solution. 
##STR7## 
Reaction 5: preparation of para(hydroxyalkyloxy)benzoic acid 
This acid is obtained through the saponification of the ester obtained upon 
the completion of reaction 4 according to the scheme: 
##STR8## 
Reaction 6: preparation of 4(methacrylyloxy)alkyloxy benzoic acid, 
4(acrylyloxy)alkyloxy benzoic acid or 4(.alpha.-chloroacrylyloxy)alkyloxy 
benzoic acid. 
The acid obtained upon completion of reaction 5 undergoes an azeotropic 
esterification in a Dean-Stark type device (which allows the water to be 
progressively eliminated as it appears during the reaction) with 
methacrylic, acrylic or .alpha.-chloroacrylic acid in the presence of 
p-toluene sulfonic acid (called APTS). 
##STR9## 
Reaction 7: the obtention of the chloric acid corresponding to the acid 
obtained by reaction 6 through reaction with thionyl chloride at ambient 
temperature in the presence of 2,6-diterbutylphenol. 
##STR10## 
The reaction is identical for the obtention of 4(methacrylyloxy)alkyloxy 
benzoic acid chloride or of 4(.alpha.-chloroacrylyloxy)alkyloxy benzoic 
acid chloride. 
Reaction 8: obtention of the monomer 
The 4'(3-methylbutyloxy)pheyl-4(methacrylyloxyalkyloxy)-benzoic acid salt 
is produced from the corresponding acid chloride obtained upon completion 
of reaction 7 and of the alkyloxphenol obtained through reaction 2. The 
reaction is carried out at ambient temperature in the presence of 
triethylamine in tetrahydrofurane (THF). 
##STR11## 
The acrylic and .alpha.-chloroacrylic monomers are obtained in the same way 
as the methacrylic monomer. 
Reaction 9: elaboration of the polymer 
The polymerization is carried out utilizing the monomer obtained in 
reaction 8 in the presence of AIBN (2-2'-azoisobutyronitrile) in toluene 
over a period of about ten hours, at 60.degree. C. in a sealed tube. 
OPERATING METHODS 
The following part of the description will deal with several specific 
operational methods of the general synthesis process, the other steps 
belonging to the prior art field. 
Reaction 2: synthesis of 4(3-methylbutyloxyphenol) 
In a 250 ml capacity Erlenmeyer, provided with a reflux cooler and a 
dropping funnel, 30.8 g of hydroquinone (or 0.28 mole) and 50 ml of 
ethanol are introduced. The device is slightly heated in order to cause 
the hydroquinone to dissolve. Thereafter, drop by drop, 43 g (0.28 mole) 
of 2-methyl-1-bromobutane are added and the mixture is brought to reflux. 
The potassium hydroxide in aqueous solution (16.6 g in 50 cc water) is 
then added and the solution is maintained at reflux for 3 hours. At this 
step, the solution presents a reddish-brown color. It is acidified by a 5N 
hydrochloric acid solution and a hexane extraction is carried out. The 
organic phase is washed with water until neutrality, dried upon magnesium 
sulfate and evaporated in a rotary evaporator. The raw product 
crystallizes at -18.degree. C. and by adding a small amount of petroleum 
ether, a light beige colored solid is obtained whose melting point in 
about 33.degree. C. The yield of the reaction is about 35%. 
Reaction 3: synthesis of para-hydroxy-methyl-benzoic acid salt. 
50 g (0.36 mole) of hydroxy-benzoic acid are dissolved in methanol in a 1 
liter capacity Erlenmeyer. The mixture is cooled to a temperature of about 
5.degree. C. Thereafter, 70 ml (1 mole) of acetyl chlorine are added drop 
by drop and the mixture is left to return to ambient temperature. A 
magnetic stirring is carried out over a period of about ten hours. The 
methanol is then flushed out under vacuum, in the same way as the 
hydrochloric acid that is formed and the remaining acetyl chloride. 55 g 
of a solid brown product are recovered. At this step, the yield of the 
reaction is 99%. A recrystallization in ethanol produces 37 g of pure 
product, the melting point of which is 123.degree. C. The overall yield of 
the reaction is 67%. 
Reaction 6: synthesis of 4(meta,.alpha.-chloro or acrylyloxy)alkyloxy 
benzoic acid. 
The following are introduced into a 100 ml capacity Erlenmeyer fitted with 
a Dean-Stark type device. 10 g (0.032 mole) of 4(hydroxyalkyloxy)benzoic 
acid, 1.7 g of monohydrated para-toluene sulfonic acid, 0.6 g of 
hydroquinone, 19.2 g (0.22 mole) of distilled methacrylic acid and 50 ml 
benzene. The mixture is brought to reflux for 17 hours. Once cold, 100 ml 
of ether are added. An organic solution is obtained which is washed with 
water several times, dried upon magnesium sulfate and evaporated to 
one-quart of its volume. The solid which is obtained is filtered and 
washed with ether. The raw product is recrystallized twice in ethanol. The 
yield of the reaction is 35%. 
It is the methacrylic compound that has been described hereinabove. The 
acrylic or .alpha.-chloroacrylic compound is obtained in the same way, 
provided that the molar proportions are respected. 
The acids obtained upon completion of reaction 6 present liquid crystal 
properties. By way of example: 
4(methacryloxy)undecanoxy benzoic acid having the formula: 
##STR12## 
has a melting point of 108.degree. C. when passing from the crystalline 
state to the isotropic state and pesents the following phase successions: 
K 69.degree. C. [N]99.degree. C. I, K designating the crystalline phase, N 
a nematic phase and I the isotropic phase. The hooks designate a 
monotropic mesophase. 
4(acrylyloxy)undecanoxy benzoic acid having the formula: 
##STR13## 
presents the following phase successions: K.sub.1 97.7.degree. C. K.sub.2 
101.degree. C. N 111.degree. C. I 
K.sub.1 and K.sub.2 each being a particular crystalline phase. 
Reaction 7: obtention of acid chlorides. The obtention of the acrylic 
derivative will now be described. The methacrylic and 
.alpha.-chloroacrylic derivatives are obtained in the same way, provided 
that the molar proportions are respected. 
A 50 liter capacity Erlenmeyer is loaded with 4.1 g (0.011 mole) of 
4(acrylyloxy)undecanoxy benzoic acid, 10 ml of distilled thionyl chloride, 
a drop of dimethylformamide then a spatula of 2.6 diterbutylparaphenol. 
The mixture is stirred for 20 minutes at ambient temperature. The 
remaining thionyl chloride is evacuated under high vacuum and 10 ml of 
tetrahydrofurane are added. A solution S1 is obtained. 
Reaction 8: monomer synthesis 
Into an Erlenmeyer are successively loaded: 0.97 g (0.006 mole) of 
4(3-methylbutyloxyphenol) obtained upon completion of reaction 2, then 2 
ml of triethylamine and 9 ml of tetrahydrofurane. A solution S.sub.2 is 
obtained. To this solution is added the solution S.sub.1 of the previous 
reaction and the mixture obtained is maintained under stirring for about 
ten hours at ambient temperature. The raw product obtained is 
chromatographed on the silica with an ethyl acetate/hexane mixture (in a 
quantity of 1 volume of acetate for 4 volumes of hexane) as eluent, 300 mg 
of pure monomer are recovered. 
The overall yield of reactions 7 and 8 is 25%. 
Reaction 9: synthesis of the polymer 
The monomer obtained in reaction 8 is introduced into a glass phial. Then 
1% by mole of 2-2'-azoisobutyronitrile and toluene are added to the 
monomer. The phial is then adapted to a ramp connected to a vacuum pump. 
Four freezing-defreezing cycles under high vacuum (10.sup.-3 mecury) are 
then carried out. The phial is thereafter sealed under vacuum and heated 
to 60.degree. C. for 6 hours. The phial is opened and the content poured 
into 800 ml of ethanol. The formed polymer precipitates. The yield of the 
reaction is about 70%. 
The polymers obtained have the following denominations: 
poly(4',3-methylbutyloxyphenyl-4-methacrylyloxyethyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-methacrylyloxypropyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-methacrylyloxybutyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-methacrylyloxypentyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-methacryloxyhecyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-methacrylyloxyheptyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-methacrylyloxyoctyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-methacrylyloxynonyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-methacrylyloxydecyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-methacrylyloxyundecyloxy-benzoic acid 
salt) 
poly(4',3-methylbutyloxyphenyl-4-acrylyloxyethyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-acrylyloxypropyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-acrylyloxybutyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-acrylyloxypentyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-acrylyloxyhexyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-acrylyloxyheptyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-acrylyloxyoctyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-acryloyloxynonyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-acrylyloxydecyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-acrylyloxyundecyloxy-benzoic acid salt) 
poly(4',3-methylbutyloxyphenyl-4-.alpha.-chloroacrylyloxyethyloxy-benzoic 
acid salt) 
poly(4',3-methylbutyloxyphenyl-4-.alpha.-chloroacrylyloxypropyloxy-benzoic 
acid salt) 
poly(4',3-methylbutyloxyphenyl-4-.alpha.-chloroacrylyloxybutyloxy-benzoic 
acid salt) 
poly(4',3-methylbutyloxyphenyl-4-.alpha.-chloroacrylyloxypentyloxy-benzoic 
acid salt) 
poly(4',3-methylbutyloxyphenyl-4-.alpha.-chloroacrylyloxyhexyloxy-benzoic 
acid salt) 
poly(4',3-methylbutyloxyphenyl-4-.alpha.-chloroacrylyloxyheptyloxy-benzoic 
acid salt) 
poly(4',3-methylbutyloxyphenyl-4-.alpha.-chloroacrylyloxyoctyloxy-benzoic 
acid salt) 
poly(4',3-methylbutyloxyphenyl-4-.alpha.-chloroacrylyloxynonyloxy-benzoic 
acid salt) 
poly(4',3-methylbutyloxyphenyl-4-.alpha.-chloroacrylyloxydecyloxy-benzoic 
acid salt) 
poly(4',3-methylbutyloxyphenyl-4-.alpha.-chloroacrylyloxyundecyloxy-benzoic 
acid salt) 
PROPERTIES OF SYNTHESIZED BODIES 
The thermograms obtained by differential heat analysis can be described in 
the following way: at high temperature an exotherm characterizes the 
transition of the first isotrope-mesophase liquid order due to the lateral 
chains whereas at low temperature a vitreous transition (Tg) is observed. 
This is characteristic of the main polymer chain. Polarizing microscopic 
analyses show that the texture of the mesophase can be "frozen" without 
there being any change in the vitreous state. The vitreous state of the 
synthetized polymers cannot be discerned in differential enthalpic 
analysis. It is possible to have an indication of its order of dimension 
through the intermediary of copolymers the vitreous transition of which is 
visible. 
By way of non-limitative example, the following phase diagrams represent 
two monomers according to the invention corresponding to n=11. 
The methacrylic type has the following chemical formula: 
##STR14## 
Its phase diagram is: 
##STR15## 
The expression (Sm A) indicates a monotropic smectic phase A. The acrylic 
derivative has the following chemical formula: 
##STR16## 
Its phase diagram is: 
##STR17## 
Sm A designates a smectic phase A. The mesophase (Sm) extending from 
5.degree. C. to 23.degree. C. is monotropic and has the properties of an 
ordinated and tilted smectic phase. 
The polymers formed from the monomers according to the invention have the 
following general chemical formula: 
##STR18## 
m designating the polymerization degree, R.sub.1 being the methyl radical 
or the chlorine or hydrogen atom. 
The properties of these polymers are resumed in table 1 given at the end of 
the present description. Table 1 compiles five polymer examples. 
for R.sub.1 =CH.sub.3 with n=2 (compound I) or n=11 (compound II) 
for R.sub.1 =H with n=2 (compound III) or n=11 (compound IV) 
and for R.sub.1 =Cl with n=6 (compound V). 
Obtained polymers I and V both have a smectic mesophase M.sub.2 and another 
phase at lower temperature M.sub.1. The vitreous transition temperature Tg 
has been theoretically calculated from copolymers. It has not been 
possible to calculate this temperature for all the compounds. .DELTA.H 
represents the enthalpy transition in cal/g. Table 1 also compiles the 
phase transition temperatures M.sub.1 to M.sub.2 (T.sub.M1/M2) and M.sub.2 
to the isotrope (T.sub.M2/I). 
It could be imagined that the chiral mesogeneous groups allow the obtention 
of cholesteric phases. In fact, the homopolymers prepared with such 
monomers only have smectic phases. It is nevertheless possible to prepare 
through copolymerization macromolecular compounds leading through heating 
to cholesteric melted masses. It is in fact possible to induce a 
sufficient distortion of the smectic structure through selecting, for 
example, as comonomers a chiral substance and a known compound that lead 
to the obtention of a polymer having a nematic phase. This polymer can be 
the following: 
##STR19## 
which has the following thermogram: 
##STR20## 
It has the differential enthalpic analysis diagram such as illustrated in 
FIG. 1. The axis of the ordinates of this diagram represent the heat 
pertaining to the mass Cm in mcal/s and the axis of the abscissae the 
temperature T in .degree.C. This diagram allows to determine the vitreous 
transition Tg temperature and the transition temperature from the nematic 
phase to the isotropic phase. It has been traced through observation of 
the heating of the crystallized product up to its melting. The nematic 
phase of this polymer extends on 95.degree. C. 
From this compound and a compound according to the invention, it is 
possible to elaborate copolymers having the general chemical formula: 
##STR21## 
with: R.sub.1 =CH.sub.3, Cl or H; and 
##STR22## 
x and y being proportionality coefficients such that x+y=1. 
Table 2, given at the end of the description, resumes the properties of 
such a copolymer. It comprises copolymers designated under the references 
VI and VII for which R.sub.1 =CH.sub.3 and n=11. According to this table, 
it will be noted that the nature of the mesophase evolves according to the 
proportions of the constituents of the copolymer. The mesophase of 
copolymer VI (x=y=0.5) is smectic while that of copolymer VII (x=0.05, 
y=0.95) is cholesteric. The transition temperatures Tg and T.sub.M/I have 
been determined according to the differential enthalpic analysis diagrams. 
FIGS. 2 and 3 represent such diagrams, respectively for the copolymers 
bearing the references VI and VII and studied herein-above. The axis of 
the ordinates of these diagrams represents the heat pertaining to the mass 
Cm in millicalories per second (mcal/s) and the axis of the abscissae the 
temperature T in .degree.C. In these diagrams, the transition temperatures 
from the isotropic phase to the mesomorphic phase can be particularly well 
observed. When the coefficient x in the copolymer is too high, it is the 
smectic order that is determinent (.DELTA.H.sub.S/I .about.2.3 cal/g). On 
the other hand, when the rate of the chiral monomer decreases, the 
cholesteric mesophase appears (.DELTA.H.sub.N/I .about.0.6 cal/g). The 
diagrams of FIGS. 2 and 3 have been traced by observing the cooling of the 
melting products. For product VI, the transition of the mesophase to the 
isotrope phase is carried out at 125.degree. C. and at cooling the 
transition occurs at 120.3.degree. C. For product VII, these transitions 
occur respectively at 127.degree. C. and 122.degree. C. 
Also comprised within the scope and spirit of the present invention is the 
object of producing copolymers of methacrylic, acrylic or 
.alpha.-chloroacrylic types. By way of non-limitative example, the 
following copolymer (reference VIl) was synthetized: 
##STR23## 
Table 3, at the end of the present description, resumes the main 
characteristics of this copolymer. Phase M.sub.1 represents the vitreous 
state. 
By means of these examples, the great potentiality of this novel family of 
thermotropic polymers presenting lateral chains with chiral structure has 
been set out. It is also possible thereafter to obtain films having 
anisotropic optical properties which could be applied within the 
non-linear optical field through addition of coloring agents or of 
molecules having both donor and electron acceptor groups. Furthermore, the 
possibility of obtaining through polymerization the cholesteric mesophase 
allows to envisage the preparation of filters, reflectors, force measuring 
apparatus, etc. 
TABLE 1 
__________________________________________________________________________ 
Ref 
R.sub.1 
n T.sub.M.sbsb.1.sub./M.sbsb.2 
T.sub.M.sbsb.2.sub./I 
Tg .DELTA.H (cal/g) 
Mesophase M.sub.2 
__________________________________________________________________________ 
I CH.sub.3 
2 60.degree. C. 
143.7.degree. C. 
-- H.sub.M.sbsb.2.sub./I = 2.2 
Smectic 
II CH.sub.3 
11 51.degree. C. 
98.5.degree. C. 
-10.degree. C. 
H.sub.M.sbsb.1.sub./M.sbsb.2 .about.2.3 
Smectic 
H.sub.M.sbsb.2.sub./I .about.3 
III 
H 2 100.degree. C. 
134.7.degree. C. 
-- H.sub.M.sbsb.2.sub./I = 1 
Smectic 
IV H 11 53.4.degree. C. 
93.4.degree. C. 
-- H.sub.M.sbsb.2.sub./M.sbsb.1 = 2.9 
Smectic 
H.sub.M.sbsb.2.sub./I = 3.3 
V Cl 6 85.5.degree. C. 
36.2.degree. C. 
H.sub.M.sbsb.2.sub./I = 2.3 
Smectic 
__________________________________________________________________________ 
TABLE 2 
______________________________________ 
Ref x y T.sub.M/I 
Tg .DELTA.H 
Mesophase M 
______________________________________ 
VI 0.5 0.5 125.degree. C. 
14.degree. C. 
2.3 cal/g 
smectic 
VII 0.05 0.95 127.degree. C. 
30.degree. C. 
0.65 cal/g 
cholesteric 
______________________________________ 
TABLE 3 
______________________________________ 
Ref T.sub.M.sbsb.1.sub./M.sbsb.2 
T.sub.M.sbsb.2.sub./I 
.DELTA.H (cal/g) 
Mesophase M.sub.2 
______________________________________ 
VIII 46.degree. C. 
101.degree. C. 
H.sub.M.sbsb.2.sub./I 2.sub. /I 
smectic 
______________________________________