Terminal modification method for improving redispersibility and suspension stability of cellulose nanocrystals

A terminal modification and redispersibility technology, applied in the field of cellulose materials, can solve the problems of unfavorable modification and application, consumption of active hydroxyl groups, etc., and achieve the effects of improving redispersibility and stability, low cost, and mild reaction conditions

Inactive Publication Date: 2019-07-05
WUHAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, these methods consume the active hydroxyl groups on the surface of cellul...

Method used

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  • Terminal modification method for improving redispersibility and suspension stability of cellulose nanocrystals
  • Terminal modification method for improving redispersibility and suspension stability of cellulose nanocrystals
  • Terminal modification method for improving redispersibility and suspension stability of cellulose nanocrystals

Examples

Experimental program
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Effect test

Embodiment 1

[0026] The prepared cellulose nanocrystal suspension was adjusted to a mass fraction of 1%, and a 0.1 mol / L sodium carbonate solution was prepared. 2.64 mL of sodium carbonate solution was added dropwise to 100 mL of cellulose nanocrystal suspension until the pH of the suspension was 9.2. Under the protection of nitrogen, the suspension was heated to 70°C, and a total of 0.116 g of 3-amino-5-mercapto-1,2,4-triazole and a total of 3.179 g of triacetoxy Sodium borohydride (that is, add 1 / 3 each time), react for 72 hours, and then add 20 mL of dilute hydrochloric acid solution with a concentration of 3 mol / L to terminate the reaction. The obtained suspension was dialyzed in distilled water for 3 days, then potassium chloride solution was added dropwise thereto to adjust the ionic strength of the suspension to 1 mol / L, and finally dialyzed again in distilled water for 3 days to obtain a terminally modified cellulose nanocrystal suspension.

Embodiment 2

[0028] This example is basically the same as Example 1, except that the terminal modification agent is changed from 3-amino-5-mercapto-1,2,4-triazole to thiadiazole molecule 2-amino-5-mercapto- 1,3,4-Thiadiazole.

Embodiment 3

[0030] This example is basically the same as Example 1, except that the pH of the cellulose nanocrystal aqueous suspension is adjusted to 7 before the reaction.

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Abstract

The invention relates to a terminal modification method for improving redispersibility and suspension stability of cellulose nanocrystals. The method comprises the following steps: firstly mixing a cellulose nanocrystal suspension and a pH buffering solution such as a sodium carbonate solution, adding an amino-containing cyclic compound and a reducing agent such as sodium triacetoxyborohydride, and performing an aldehyde amine condensation reaction and a reduction reaction to bond reactive aldehyde groups at the terminal of the cellulose nanocrystals to amino and simultaneously reduce a carbon-nitrogen double bond into a more stable carbon-nitrogen single bond. According to the method provided by the invention, through the above modification, an original rod-like morphology and crystal structure of the cellulose nanocrystals and hydroxyl used as hydrogen bond driving force and a negative charge sulfonate group at the surface of the nanocrystals are retained, and the electrostatic repulsion effect of surface negative charges (the sulfonate group) and the steric hindrance effect of a terminal modified molecule (the cyclic compound) of the cellulose nanocrystals are fully utilized, sothat the redispersibility and stability in an aqueous suspension of the cellulose nanocrystals are efficiently improved.

Description

technical field [0001] The invention relates to the technical field of cellulose materials, in particular to a terminal modification method for improving the redispersibility and suspension stability of cellulose nanocrystals. Background technique [0002] Natural cellulose from various sources can be treated with acid hydrolysis to remove the amorphous and semi-crystalline regions, and the resulting rigid cellulose nanocrystals are a new type of green nanomaterial. Cellulose nanocrystals have excellent physical and chemical properties, such as renewability, biodegradability, biocompatibility, low toxicity, high specific modulus, abundant active hydroxyl groups on the surface, liquid crystallinity, special rod-like morphology, high crystallinity Therefore, it has received a lot of attention from academia and industry, and it has been reported in the literature that it is widely used in composite materials, papermaking, packaging, catalysis, energy and optics, electronics, se...

Claims

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Application Information

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IPC IPC(8): C08B15/06
CPCC08B15/06
Inventor 林宁王昱霞王润东杜超
Owner WUHAN UNIV OF TECH
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