JPH05310943A - Synthesis of branched liquid-crystalline silicone compound - Google Patents

Abstract

PURPOSE:To obtain a product free from residual SiH group in the synthesis of a branched liquid-crystalline silicone compound comprising the addition of a liquid crystalline compound to a silicone compound having SiH group by hydrosilylation reaction. CONSTITUTION:A liquid crystalline silicone compound having chemical stability can be produced by adding mesogen group to a silicone compound having excess SiH group based on the introducing liquid crystalline compound (mesogen group) and adding a compound free from mesogen and having C-C double bond on the terminal to the residual SiH group.

Description

Detailed Description of the Invention

[0001]

The compound produced by the method of the present invention is used as a material for optical elements such as flexible liquid crystal displays and liquid crystal blinds, and electrorheological fluid actuators for vibration absorption and torque transmission.

[0002]

2. Description of the Related Art As shown in FIG. 1, the type of liquid crystalline silicone compound is a main chain type (a), a side chain type (b), or both ends type (c) depending on the bonding position of the liquid crystal expressing structure (mesogen). , And one-end type (d). Among these compounds, side-chain type liquid crystal compounds have been extensively studied as new functional liquid crystal materials. As the method for synthesizing this compound, a method in which a siloxane-based monomer having a mesogen bonded thereto is added or condensed, and a compound in which a mesogen is bonded to a linear or cyclic silicone compound containing a bonding group in the molecular chain is added or condensed. The method is commonly used. Among them, a method of adding a compound (mesogen group) containing a mesogen to a silicone compound containing a SiH group and having a carbon-carbon double bond at a terminal by a hydrosilylation reaction is easy and well used.

[0003]

In the reaction of adding a plurality of mesogen groups to a silicone compound having a plurality of SiH groups in one molecular chain, an excessive amount of mesogen groups is charged in an equivalent amount to the SiH groups. , The reaction is not completed even if the reaction conditions such as the type or amount of catalyst or solvent are changed,
The SiH group may remain, and this tendency is particularly strong when a long chain or bulky mesogen group is added. When the SiH group is left to remain in the reaction product, the SiH group has relatively high reactivity and is likely to cause a trouble such as subsequent treatment or modification during use as a product. The present invention proposes a reaction method in which a mesogenic group is efficiently added and such SiH group is not left in a reaction product.

[0004]

Means for Solving the Problems As a result of repeated studies on the addition of a mesogenic group to a silicone compound, the present inventors have found that the hydrosilylation reaction does not contain a mesogenic group and has a carbon-carbon double bond at the end. It is easier to quantitatively complete a compound having a relatively low molecular weight, and it is preferable to use Si rather than excess mesogenic groups.
It was found that the reaction was easier to complete in the case of excess H groups. Therefore, instead of the conventional method of adding a mesogen group to a silicone compound having a predetermined amount of SiH groups corresponding to the desired addition amount of mesogen groups to one molecular chain, a silicone compound containing an excess of SiH groups over a predetermined amount is used. To the remaining SiH groups,
As a result of trying a method of adding a relatively low molecular weight compound having no carbon-carbon double bond at the terminal without containing mesogen, a side chain type liquid crystallinity in which a predetermined amount of mesogen group is added and SiH group does not remain It has been found to be extremely convenient to synthesize silicone compounds.

That is, in the constitution of the present invention, a compound containing a liquid crystal expressing structure (mesogen) in a silicone compound having a plurality of SiH groups in one molecular chain and having a carbon-carbon double bond at a terminal (mesogen group). In the method of synthesizing a side chain type liquid crystalline silicone compound by adding a plurality of) by a hydrosilylation reaction, after the addition reaction of the mesogen group to the SiH group, the remaining SiH group is terminated with no mesogen. It is a method for synthesizing a side chain type liquid crystalline silicone compound in which a compound having a carbon-carbon double bond is added.

In the present invention, one molecule has a plurality of Si atoms.
As a silicone compound having an H group, -SiHRO-
(Wherein R represents hydrogen or an alkyl group having 1 to 6 carbon atoms or a phenyl group), such as a linear or cyclic homopolymer of hydroalkyl (or hydrophenyl) siloxane, dihydrosiloxane, or the like. -SiR ¹ R ² O-, such as dimethylsiloxane and phenylmethylsiloxane (wherein R ¹ and R ² represent an alkyl group having 1 to 6 carbon atoms or a phenyl group)
Typical examples include copolymerization with siloxane represented by Even if an aliphatic or aromatic molecule such as alkylene or phenylene is present in the molecular chain via a bonding group such as an ester group, an amide group or an ether group, the effect of the present invention is not particularly hindered.

The liquid crystal expression structure, so-called mesogen, includes Schiff base type, azo type, azoxy type, biphenyl type, terphenyl type, benzoic acid type, cyclohexylcarboxylic acid type, phenylcyclohexane type, biphenylcyclohexane type, cholesteryl. Examples include a core molecular structure that exhibits liquid crystallinity of a conventionally known low-molecular liquid crystal such as a system. For more information, see Akio Sasaki "Liquid Crystal Electronics" (Ohmsha) and Advances.
in Polymer Science 59, P1
03, Springer-Verlag (1984), a typical example thereof is described.

[0008] Carbon-terminated include mesogenic - compounds with carbon double bonds (mesogen groups), mesogenic and carbon - between carbon double bond, -C _m H _2m - or - (SiR ³ R ⁴⁾ _m −
(Where m is an integer from 1 to 18 and R ³ and R ⁴ are alkyl groups such as methyl and ethyl) are often used through a conventionally known molecular chain called a spacer. ..

The hydrosilylation reaction, that is, -SiH + H ₂ C = CH- → -SiCH ₂ CH _2- generally proceeds relatively easily in the presence of a trace amount of a platinum catalyst, but it is peroxidized under special conditions. In some cases, it is performed using a thing.
The method of the present invention is effective in any reaction. S
In the reaction between the iH group and the mesogen group, it is difficult to react until the SiH group completely disappears by an equimolar reaction. Usually, an excess mesogen group is charged with respect to the SiH group. Is not easy to eliminate, and in many cases, a troublesome process such as passing through the adsorbent column several times is required to completely remove the mesogenic group after the reaction. In addition, mesogenic groups are often more expensive than silicone compounds containing SiH groups, and it is not economical to use mesogenic groups in excess.

As a compound which does not contain mesogen and has a carbon-carbon double bond only at one end, H ₂ C═CH (CH ₂ )
_n R or H ₂ C═C [(CH ₂ ) _n R] ₂ (wherein R is hydrogen or an alkyl group such as methyl or ethyl directly or through a bonding group such as ester, ether or amide, It is an aromatic group such as phenyl or biphenyl, or a silicon-containing group such as alkylsilane or siloxane, and n is 0.
Alternatively, it is an integer of 5 or less. Further, in the case of the compound having the latter structure, R and n may not be the same). Typical examples thereof include ethylene, propylene, styrene, vinyltrimethylsilane and the like.

The present invention will be specifically described below with reference to examples.

Example 1 Silicone random copolymer of hydromethyl siloxane (HMS) and dimethyl siloxane (DMS) (HM
S: DMS = 6: 4 molar ratio, molecular weight about 3000) 33 g
And the liquid crystal compound (mesogenic group) 6 shown in the following (Chemical Formula 1)
8 g (5/6 molar equivalent to HMS in silicone) was dissolved in 500 ml of tetrahydrofuran (THF), 31 mg of chloroplatinic acid (hexahydrate) was added, and the temperature was 60 ° C.
The mixture was reacted at reflux for 1 hour. Then, vinyl trimethylsilane (VTMS) 6.0 gr (1.2 mol equivalent to HMS in silicone) and chloroplatinic acid (same as above)
6.2 mg was added and the reaction was continued for another hour. After the reaction, THF was distilled off, and the mixture was further vigorously stirred in ethanol at 70 ° C to extract and remove unreacted mesogen groups and VTMS. Infrared spectrum and NMR of the product
From the spectrum, the SiH group was completely disappeared, the mesogenic group was added to 5/6 of HMS in the silicone according to the charged amount, and the remaining HMS was completely added by VTMS.

[0013]

[Chemical 1]

Comparative Example 33 g of the silicone copolymer used in Example 1 and VTMS
160 g (1/6 mol equivalent to HMS in silicone) was dissolved in 160 ml of THF, 5.2 mg of chloroplatinic acid (hexahydrate) was added, and the mixture was reacted at 60 ° C. under reflux for 1 hour. Then, the mesogenic group 82 used in Example 1 was used.
g (1 molar equivalent to HMS in silicone), TH
F400 ml and chloroplatinic acid (same as above) 82 mg were added, and the reaction was continued for another 1 hour. After the reaction, unreacted materials were extracted and removed in the same manner as in Example 1. From the infrared spectrum and the NMR spectrum of the reaction intermediate and the product, V
Although TMS addition was complete, about 2% of SiH groups remained despite the excess charging of mesogen groups.

[0015]

As described above, according to the present invention,
When a side chain type liquid crystalline compound is synthesized by adding a compound having a mesogen and having a carbon-carbon double bond at the end to a silicone compound having a plurality of SiH groups in one molecular chain by hydrosilylation reaction As a result of producing a compound having no residual SiH group, a product having excellent stability can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view showing a structure of a liquid crystalline silicone compound.

Claims (1)

[Claims] 1. A silicone compound having a plurality of SiH groups in one molecular chain, which contains a liquid crystal developing structure (mesogen), and a plurality of compounds having a carbon-carbon double bond at a terminal (mesogenic group) are hydrolyzed. In a method of synthesizing a side chain type liquid crystalline silicone compound by addition by a silylation reaction, after adding a mesogen group to a SiH group, the remaining SiH group does not contain a mesogen and has a carbon-carbon double bond at the end. A method for synthesizing a side chain type liquid crystalline silicone compound, which comprises adding a compound having