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Liquid crystal elastomer based on allyl selenide dynamic covalent bonds as well as preparation method and application of liquid crystal elastomer

A technology of allyl selenide and liquid crystal elastomer, applied in liquid crystal materials, chemical instruments and methods, organic chemistry, etc., can solve the problems of polarity and pH instability, material structure requirements, etc., and achieve good continuous performance , avoid irreversible damage, stimulate stable effect

Active Publication Date: 2022-07-05
SUZHOU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, because of the multi-responsiveness of disulfide, it is unstable to polarity and pH, and there are requirements for the material structure

Method used

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  • Liquid crystal elastomer based on allyl selenide dynamic covalent bonds as well as preparation method and application of liquid crystal elastomer
  • Liquid crystal elastomer based on allyl selenide dynamic covalent bonds as well as preparation method and application of liquid crystal elastomer
  • Liquid crystal elastomer based on allyl selenide dynamic covalent bonds as well as preparation method and application of liquid crystal elastomer

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0065] Example 1: Preparation of Difunctional Hydroxyl Terminated Allyl Selenide Monomer

[0066] Selenium powder (800 mmol, 63.2 g) was weighed and placed in a 1 L three-necked flask, sodium hydroxide (750 mmol, 30.0 g) was dissolved in 400 mL of water, and then added to the three-necked flask, and argon was passed to remove oxygen. Sodium borohydride (107 mmol, 4.0 g) was dissolved in an aqueous solution of sodium hydroxide (2.0 g, 50 mL), slowly dropped into the above system, and reacted at room temperature for 2 h. 1 g of tetrabutylammonium bromide was added, and the temperature was raised to 50 °C. 6-Chloro-n-hexanol (400 mmol, 54.7 g) was dissolved in 400 mL of tetrahydrofuran, and the above system was added slowly. After reacting for 12 h, the reaction solution was extracted with ethyl acetate to obtain an organic phase, which was dried over anhydrous sodium sulfate, and separated by column chromatography to obtain hydroxyl-terminated diselenide (HO-C 6 -Se 2 ). wil...

Embodiment 2

[0070] Example 2: Preparation of Liquid Crystal Elastomer

[0071] Dissolve 1,4-bis[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (2.5 mmol, 1.68 g) in 8 mL of tetrahydrofuran, dithiothreitol ( 2.0 mmol, 0.31 g) was dissolved in 2 mL of tetrahydrofuran, all were added to a 25 mL three-necked flask, after ventilation and deoxygenation, 50 μL of triethylamine was added. After 12h of reaction, the HO-C 6 -Se 1 (1 mmol, 0.41 g) and 1,6-hexamethylene diisocyanate (2 mmol, 0.34 g) were respectively dissolved in 2 mL of toluene and added to the three-necked flask in turn, and 100 ppm of dibutyltin dilaurate was added as a catalyst. After fully stirring, the mixture was dissolved in a 6×8 cm polytetrafluoroethylene mold, placed at room temperature for 4 hours to slowly volatilize the low-boiling organic solvent tetrahydrofuran, and then placed in a 60 ℃ oven for 12 hours to make the reaction fully, and then 100 Annealed at ℃ for 12h to obtain a liquid crystal elastomer.

[...

Embodiment 3

[0075] Example 3: Stretch orientation of liquid crystal elastomer

[0076] The obtained liquid crystal elastomer film was cut into a long strip, and a stable external force was applied to the sample strip at a rate of 10 mm / min at 50° C. to a strain of 50% with a stretcher. The sample was then rapidly cooled to room temperature, and the light intensity was 40 mWcm -2 Irradiated under 405 nm UV light for 1 h, the internal allyl selenide could undergo reversible addition-fragmentation chain transfer reaction, thereby obtaining a liquid crystal elastomer with successful orientation fixation.

[0077] Differential scanning calorimetry (DSC) curves and polarized light microscopy images proved that the liquid crystal elastomers were successfully oriented, and the results were as follows Figure 7-8 shown. It can be seen from the figure that the liquid crystal elastomer material has been successfully oriented, and its phase transition temperature (T NI) is 70°C. The corresponding...

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Abstract

The invention discloses a preparation method of a liquid crystal elastomer based on an allyl selenide dynamic covalent bond, which comprises the following steps: S1, carrying out Michael addition reaction on a bifunctional-terminated liquid crystal monomer and dithiol under the action of a catalyst to obtain a liquid crystal prepolymer; and S2, under the action of a catalyst, carrying out a cross-linking reaction on the liquid crystal prepolymer, the bifunctional-terminated allyl selenide and diisocyanate to obtain the liquid crystal elastomer based on the allyl selenide dynamic covalent bond. Compared with other preparation modes in which photoinitiators participate, the preparation method disclosed by the invention does not damage the structure of a photoresponse dynamic covalent bond in the preparation process. Compared with other photoresponse dynamic covalent bonds, the liquid crystal elastomer based on the allyl selenide dynamic covalent bonds prepared by the invention can spontaneously perform dynamic exchange under irradiation without a photoinitiator, and has sustainable dynamic performance. In addition, network recombination can be achieved only through a single light source such as 405 nm visible light, and various stimuli to heat and the like are stable.

Description

technical field [0001] The invention relates to the technical field of organic synthesis, in particular to a liquid crystal elastomer based on dynamic covalent bonds of allyl selenide and a preparation method and application thereof. Background technique [0002] Liquid crystal elastomers (LCEs) are a combination of liquid crystal and polymer networks that combine the properties of polymeric elastomers (entropic elasticity) and liquid crystals (self-organization), which exhibit robust and reversible actuation when subjected to various stimuli . LCEs couple their local molecular stimulus-response changes with macroscopic shape changes when heated to their nematic-isotropic transition temperature (T NI ) or above, the liquid crystal elastomer shrinks along the direction of director alignment and expands along the orthogonal direction. When the temperature drops to T NI At the following times, this process is reversed, usually with a change in shape or in other properties suc...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C391/00C08G18/67C08G18/52C08G75/045C09K19/38
CPCC07C391/00C08G18/677C08G18/52C08G75/045C09K19/3857Y02P20/55
Inventor 潘向强陈偲偲朱健李清园陆劭朴
Owner SUZHOU UNIV
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