Preparation method of super-flexible rosin gel

Abstract

The invention discloses a preparation method of super-flexible rosin gel, which comprises the following steps: utilizing rosin to initiate a ring-opening polymerization reaction of lipoic acid to form a first network, and adding caffeic acid to form hydrogen bond combination with the lipoic acid and the rosin to generate a second network, so that the gel is endowed with excellent tensile property through a high-entanglement double-network structure; and the gel has super flexibility.

Description

Technical Field

[0001] The invention belongs to the field of natural polymer materials, and in particular relates to a method for preparing super-flexible rosin gel. Background Art

[0002] Most of the existing gel materials are petroleum-based materials, which are not in line with the concept of green and sustainable development. In order to solve the environmental problems it brings, gels with various properties have been developed using biomass materials, but the pursuit of high performance has led to increased structural complexity and synthesis difficulty, which has also increased costs. Therefore, it is a crucial challenge to prepare gel materials with comprehensive and complex properties from bio-based raw materials through an extremely simplified route. Based on this, the present invention provides a method for preparing ultra-flexible rosin gel, which develops ultra-flexible gel by combining functional small molecule lipoic acid with natural resin rosin. Summary of the invention

[0003] The object of the present invention is to provide a method for preparing super-flexible rosin gel, which uses rosin to initiate the self-polymerization of lipoic acid and form a double network structure with caffeic acid and rosin, thereby giving the gel super-stretchability and excellent flexibility.

[0004] To achieve the above object, the present invention adopts the following technical solution: A super-flexible rosin gel, the preparation method of which comprises the following steps: (1) Add lipoic acid to anhydrous ethanol and stir at room temperature until the lipoic acid is completely dissolved to form a lipoic acid solution; (2) Add caffeic acid and rosin to the lipoic acid solution obtained in step (1), stir evenly, heat and react, and form rosin gel after cooling to room temperature.

[0005] Furthermore, the solubility of the thioctic acid solution obtained in step (1) is 10wt%-30wt%.

[0006] Furthermore, the amount of the lipoic acid solution in step (2) is converted according to the mass ratio of lipoic acid to caffeic acid and rosin contained therein of 1:1:1-1:1:3.

[0007] Furthermore, the heating reaction in step (2) is carried out at a temperature of 90°C-110°C and for a time of 2h-5h.

[0008] Lipoic acid (TA) is a naturally occurring small molecule substance and an essential coenzyme for animal aerobic metabolism. There are two types of dynamic chemical bonds in its structure, namely, dynamic covalent disulfide bonds and non-covalent hydrogen bonds of carboxyl groups. In the present invention, the disulfide bonds of lipoic acid are affected by rosin to undergo a ring-opening polymerization reaction, and the thiol groups after the ring opening are combined with the phenolic hydroxyl group and the carboxyl group in caffeic acid. At the same time, the carboxyl groups of lipoic acid can form multiple hydrogen bonding forces with the carboxyl groups of rosin and caffeic acid, thereby forming a gel network with a dynamic stable structure.

[0009] The significant advantages of the present invention are: (1) The method of the present invention is simple, the conditions are mild, the polymerization of lipoic acid initiated by rosin has a good effect, and the depolymerization of lipoic acid can be effectively prevented.

[0010] (2) The gel prepared by the present invention has good tensile properties and good flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a reaction mechanism diagram for preparing super-flexible rosin gel in the present invention.

[0012] Figure 2 This is a graph showing the tensile properties of the gel prepared in Example 2.

[0013] Figure 3 This is the SEM image of the gel prepared in Example 2. DETAILED DESCRIPTION

[0014] A method for preparing super-flexible rosin gel comprises the following steps: (1) adding thioctic acid to anhydrous ethanol and stirring at room temperature until the thioctic acid is completely dissolved to form a thioctic acid solution with a solubility of 10wt%-30wt%; (2) adding caffeic acid and rosin to the lipoic acid solution obtained in step (1) in a mass ratio of lipoic acid to caffeic acid and rosin of 1:1:1-1:1:3, stirring evenly, heating at 90°C-110°C for reaction for 2h-5h, and cooling to room temperature to form a rosin gel.

[0015] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0016] Example 1 (1) Weigh 5 g of lipoic acid, add it to 20 mL of anhydrous ethanol, and stir at room temperature until the lipoic acid is completely dissolved to form a lipoic acid solution with a solubility of 20 wt%; (2) 5 g of caffeic acid and 5 g of rosin were added to the lipoic acid solution obtained in step (1), stirred evenly, and heated at 100° C. for 4 h. After cooling to room temperature, rosin gel was formed.

[0017] Example 2 (1) Weigh 5 g of lipoic acid, add it to 20 mL of anhydrous ethanol, and stir at room temperature until the lipoic acid is completely dissolved to form a lipoic acid solution with a solubility of 20 wt%; (2) 5 g of caffeic acid and 10 g of rosin were added to the lipoic acid solution obtained in step (1), stirred evenly, and heated at 100° C. for 4 h. After cooling to room temperature, rosin gel was formed.

[0018] Figure 2 The tensile properties of the obtained gel are shown in Figure 2. As can be seen from the figure, the obtained gel has excellent tensile properties.

[0019] Figure 3 The SEM image of the obtained gel shows that the obtained gel forms a highly entangled network structure.

[0020] Example 3 (1) Weigh 5 g of lipoic acid, add it to 20 mL of anhydrous ethanol, and stir at room temperature until the lipoic acid is completely dissolved to form a lipoic acid solution with a solubility of 20 wt%; (2) 5 g of caffeic acid and 15 g of rosin were added to the lipoic acid solution obtained in step (1), stirred evenly, and heated at 100° C. for 4 h. After cooling to room temperature, rosin gel was formed.

[0021] Comparative Example 1 (1) Weigh 5 g of lipoic acid, add it to 20 mL of anhydrous ethanol, and stir at room temperature until the lipoic acid is completely dissolved to form a lipoic acid solution with a solubility of 20 wt%; (2) Take 10 g of rosin and add it to the lipoic acid solution obtained in step (1). After stirring evenly, heat at 100° C. for 4 h and cool to room temperature.

[0022] Comparative Example 2 (1) Weigh 5 g of lipoic acid, add it to 20 mL of anhydrous ethanol, and stir at room temperature until the lipoic acid is completely dissolved to form a lipoic acid solution with a solubility of 20 wt%; (2) Add 5 g of catechol and 10 g of rosin to the lipoic acid solution obtained in step (1), stir evenly, heat at 100° C. for 4 h, and cool to room temperature.

[0023] The performance of the gel samples prepared in the examples and comparative examples was tested, and the results are shown in Table 1.

[0024] Table 1 Performance test results of gel samples obtained in Examples and Comparative Examples

[0025] As shown in Table 1, the tensile strain of the rosin gel obtained in the examples can reach more than 4300%, and the tensile strength is more than 73 kPa, among which Example 2 has the best effect. This is because the organic combination of lipoic acid, caffeic acid and rosin in the examples forms a double network structure, which gives the gel excellent flexibility. Compared with the examples, Comparative Example 1 cannot form a good double network structure, resulting in poor tensile strain and tensile strength of the gel. The catechol structure of Comparative Example 2 does not contain a carboxyl group, and the hydrogen bond with lipoic acid and rosin is weak, resulting in poor tensile strain and tensile strength of the gel.

[0026] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for preparing super-flexible rosin gel, characterized in that: The following steps are involved: (1) Add lipoic acid to anhydrous ethanol and stir at room temperature until the lipoic acid is completely dissolved to form a lipoic acid solution; (2) Add caffeic acid and rosin to the lipoic acid solution obtained in step (1), stir evenly, heat and react, and form rosin gel after cooling to room temperature.

2. The method for preparing a super-flexible rosin gel according to claim 1, characterized in that: The solubility of the thioctic acid solution obtained in step (1) is 10wt%-30wt%.

3. The method for preparing a super-flexible rosin gel according to claim 1, characterized in that: The amount of the thioctic acid solution in step (2) is calculated based on the mass ratio of thioctic acid to caffeic acid and rosin contained therein of 1:1:1-1:1:

3.

4. The method for preparing a super-flexible rosin gel according to claim 1, characterized in that: The temperature of the heating reaction in step (2) is 90°C-110°C, and the time is 2h-5h.

5. An ultra-flexible rosin gel prepared by the method according to any one of claims 1 to 4.

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