CN1663990A - Chitosan/montmorillonite nano composite materials and method for preparing same - Google Patents

Abstract

The invention discloses a chitosan/montmorillonite nanocomposite material and a preparation method thereof. It is characterized in that chitosan is first dissolved in a certain concentration of acid solution, and then the chitosan solution is slowly dropped into the montmorillonite suspension under the condition of constant temperature stirring, and a small amount of plasticizer and cross-linking agent are added. The composite material prepared by the invention has excellent dry and wet mechanical properties after molding, good biocompatibility and stability, and can be used for biological structure materials, active substance controlled release materials, electrode modification materials and the like.

Description

A kind of chitosan/montmorillonite nanocomposite material and preparation method thereof

technical field

The invention relates to a chitosan/montmorillonite nanocomposite material and a preparation method thereof.

Background technique

Chitosan is the deacetylated derivative of the most abundant natural macromolecule-chitin on the earth. Its scientific name is poly-N-acetyl-D-glucosamine. A linear polymer of 2-acetamido-2-deoxy-D-glucopyranose chains connected by bonds. Because of its good film-forming properties, gel properties, degradability, and biocompatibility, it has been widely used in the fields of chemical industry, food, medicine, and agriculture (In Polymeric Biomaterials, S.Dumitriu, Ed.Marcel Dekker, New York, 1994; In Progress in Biomedical Polymers, Plenum Press, New York, 1990; Wo Pat. 96 02, 260, 1994). In particular, chitosan molecules have active groups _-NH2 and -OH, which have strong chelating and adsorption effects on certain metal ions, anions and organic substances. Therefore, they have been used as electrode modification materials for electrochemical determination. (Microchemical Journal, 2001, 69:81-87). Patent CN 1373361 discloses a blood glucose measurement electrode modified by chitosan solution. Chitosan is used as an electrode sensitive material glucose oxidase immobilization material, which improves the stability, life and reproducibility of the electrode, and improves the Anti-interference ability.

However, due to the large number of hydrophilic groups in the chitosan molecule, there are problems such as poor mechanical properties, high brittleness, poor water resistance and unsuitability for acidic environments in practical applications. For this reason, in recent years, scholars at home and abroad have tried to modify chitosan by grafting or blending with polymers, but its performance still cannot meet the practical requirements; another domestic researcher has explored the use of inorganic materials to improve chitosan The performance of carbohydrates is expected to develop new packaging materials and scaffold materials for tissue engineering. (Acta Advanced Chemistry, 2001, 22(12): 2113-2116; Chem. Mater. 2003, 15: 3774-3780; Journal of Wuhan University (Natural Science Edition), 2002, 48(6): 701-704).

Contents of the invention

The purpose of the invention is to disclose a chitosan/montmorillonite nanocomposite material and a preparation method thereof, so as to overcome the poor mechanical properties, high brittleness, poor water resistance and unsuitability of chitosan in the prior art. defect.

Technical concept of the present invention is such:

The inventor conceives that chitosan and montmorillonite are compounded by an intercalation composite method to obtain a chitosan/montmorillonite nanocomposite material.

Montmorillonite is a 2:1 layered silicate. In each unit cell, two silicon-oxygen tetrahedrons are connected to an aluminum-oxygen octahedron by sharing oxygen atoms. The close packing of tetrahedrons and octahedrons makes Montmorillonite has a highly ordered lattice structure. Because of its good biocompatibility, it has been successfully used in fields such as medicine and cosmetics (Biomed. ): 359-368), in addition, its interaction with biomacromolecules has also been reported, such as the self-assembly of charged proteins (cytochrome, myoglobin, lysozyme, etc.) and montmorillonite (Science, 1994, 65: 370 -373; J.Am.Chem.Soc., 1995, 117: 6117-6123), the adsorption of proteins such as bovine serum albumin on the surface of montmorillonite, etc. (J.Colloid and inter.Sci., 1994, 166: 89- 94; Colloid and Surfaces A: Physicalchemical and Engineering Aspects, 1993, 75:85-93). It can be seen that the application of montmorillonite as a biological material in the modification of matrix materials has great application value.

The preparation method of chitosan/montmorillonite composite material of the present invention, comprises the steps:

Add 0.5-30 parts of montmorillonite to 900-10000 parts of water, and stir at a speed of 200-1000 rpm for 0.3-1.0 hours to obtain a stable montmorillonite suspension A;

1-30 parts of chitosan are dissolved in an acid solution with a weight concentration of 0.5-5%, and the pH value is adjusted to 3-6 to obtain a solution B;

70-99 parts of chitosan are dissolved in an acid solution with a weight concentration of 1-5%, and the pH value is adjusted to 3-6 to obtain solution C;

Suspension A is heated to 40-90°C, slowly add solution B dropwise under stirring, keep warm for 0.5-2 hours, add solution C, 1-5 parts of plasticizer and 1-5 parts of cross-linking agent, react for 2-24 hours, Composite materials are produced.

The parts of each of the above-mentioned components are all parts by weight, and are also all parts by weight unless otherwise specified below.

The montmorillonite used in the present invention is sodium-based or/and potassium-based montmorillonite with a total cation exchange capacity (CEC) of 50-200meq/100g, preferably 70-120meq/100g. If the CEC is greater than 200meq/100g, the higher Coulomb force between layers makes it difficult for montmorillonite to be uniformly dispersed in the polymer matrix; when the exchange capacity is lower than 50meq/100g, montmorillonite cannot effectively interact with chitosan molecules, The compatibility with the matrix will be very poor, which will easily cause the montmorillonite to not be uniformly dispersed in the chitosan matrix, and its particle size is 40-100 μm;

Relative to 100 parts of chitosan, the amount of montmorillonite in the present invention is 0.5 to 30 parts by weight. When the amount is too low, the montmorillonite is not enough to produce sufficient reinforcement; when the amount exceeds 30 parts, the amount of montmorillonite Soil cannot be uniformly dispersed in chitosan. In the present invention, the optimal dosage of montmorillonite is 5-15 parts.

The plasticizer is at least one of glycerin, oleic acid, stearic acid, ethylene glycol or polyethylene glycol.

The crosslinking agent is at least one of formaldehyde, acetaldehyde, glyoxal, glutaraldehyde, glucodial or epichlorohydrin.

The acid is at least one of formic acid, acetic acid, lactic acid and oxalic acid.

The chitosan obtained by the method of the invention has good mechanical properties, low brittleness and good water resistance, and is suitable for acidic environments. The composite material prepared by the invention has excellent dry and wet mechanical properties after molding, good biocompatibility and stability, and can be used for biological structure materials, active substance controlled release materials, electrode modification materials and the like.

Description of drawings

Fig. 1 is the infrared spectrogram of chitosan/montmorillonite composite material.

Fig. 2 is the X-ray diffraction pattern of chitosan/montmorillonite composite material.

Fig. 3 is the thermogravimetric curve of chitosan/montmorillonite composite material.

Detailed ways

The present invention is described in detail by experimental examples below, it is necessary to point out that this embodiment is only used to further illustrate the present invention, can not be interpreted as the restriction to protection scope of the present invention, those skilled in the art can according to above-mentioned the present invention Some non-essential improvements and adjustments have been made to the content.

Example 1

Add 0.5g of sodium montmorillonite with a cation exchange capacity of 100meq/100g and a particle size of 50μm, add 25ml of water, and stir at a speed of 300 rpm for 20min after uniform dispersion to obtain a stable montmorillonite suspension A.

0.4g of chitosan with a degree of deacetylation of 92% was dissolved in 100ml of 1% acetic acid solution, and the pH value was controlled at 5.0 to obtain solution B;

This chitosan of 9.6g is dissolved in the acetic acid solution of 400ml 1%, adjusts pH value to be 5.0, obtains solution C.

Suspension A was heated to 60°C, solution B was added dropwise under stirring, and kept warm for 0.5 hours, solution C, 0.5 g of glycerol and 0.4 g of glutaraldehyde solution were added dropwise, and reacted for 2 hours to obtain a composite material.

According to the national standard (GB/4456-84), the dry and wet tensile strength of the chitosan/montmorillonite composite material, the dry and wet elongation at break are 77.5Mpa, 28.1Mpa, 23.9% respectively , 53.4%.

After the chitosan/montmorillonite composite material was soaked in hydrochloric acid solution with a pH value of 5.0-6.0 for 1 hour, the film sample of the composite material was basically insoluble and the morphology remained unchanged.

The swelling degree of chitosan/montmorillonite composite is 157%.

Its infrared spectrogram is shown in Figure 1, its X-ray diffraction chart is shown in Figure 2, and its thermogravimetric curve is shown in Figure 3.

The testing methods for mechanical properties, acid stability and swelling properties are as follows:

(1) Mechanical properties

Tensile strength and elongation at break were measured using a Shimadzu AG-2000A material universal testing machine.

The fully dried chitosan/montmorillonite composite material or chitosan sample is subjected to stress-strain test with a tensile speed of 10mm/min.

Put the fully dried strip sample in deionized water at 25°C to fully swell, wipe off the surface moisture with filter paper, and immediately perform a stress-strain test. The tensile strength σ and elongation at break ε follow the formula:

$\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; A</span>}}$ $\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="0"\; label="l"\; filenames="A20051002435400101.png"\; state="\{\{state\}\}">l</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; \%</span>$

In the formula, F is the load (N) when the diaphragm breaks, A is the initial cross-sectional area of the diaphragm (m ² ), l ₀ is the effective length of the diaphragm, and l is the length between the measuring lines when it breaks. Each data is the average of 3 experiments.

(2) Acid stability

The samples of 5cm×5cm were respectively placed in hydrochloric acid solutions with pH values of 5.0, 5.5 and 6.0, and the dissolution of the membrane samples in the solution was observed.

(3) Swellability

Vacuum-dry the 5cm×5cm sample and immerse it in 100ml phosphate buffered saline solution (PBS) (25-27℃) to swell fully for 24 hours, take it out and quickly dry the surface liquid with absorbent paper, weigh (m), and then Place the film in a vacuum oven at 110°C for 24 hours, take it out and weigh it (m ₀ ), and calculate the sample swelling rate (S _w ) according to the following formula:

S _w =(mm ₀ )/m×100%

Example 2

Add 1.0g of sodium-based montmorillonite with a cation exchange capacity of 90meq/100g and a particle size of about 60μm, add 50ml of water, and stir for 20min at a speed of 800 rpm to obtain a stable montmorillonite suspension A . 0.8g degree of deacetylation is that chitosan of 92% is dissolved in the formic acid solution of 150ml 1%, adjusts pH value with NaOH to be 4.0, obtains solution B, and this chitosan of 9.2g is dissolved in the formic acid solution of 300ml 1%, Control the pH value at about 5.0 to obtain solution C. Suspension A was heated to 50°C, solution B was added dropwise, stirred for 0.5 hours, solution C, 0.5 g of ethylene glycol and 1.0 g of formaldehyde solution with a weight concentration of 36% were added dropwise, and reacted for 2 hours to obtain a composite material.

According to the national standard (GB/4456-84), the dry and wet tensile strength of the chitosan/montmorillonite composite material, the dry and wet elongation at break are 80.2Mpa, 29.5Mpa, 22.6% respectively , 51.8%.

After the chitosan/montmorillonite composite material was soaked in hydrochloric acid solution with a pH value of 5.0-6.0 for 1 hour, the film sample of the composite material was basically insoluble and the morphology remained unchanged.

The swelling degree of chitosan/montmorillonite composite is 115%.

The detection methods of mechanical properties, acid stability and swelling performance are the same as in Example 1.

Example 3

Add 1.5g of potassium-based montmorillonite with a cation exchange capacity of 80meq/100g and a particle size of about 40μm, add 75ml of water, and stir at a speed of 500 rpm for 20 minutes to obtain a stable montmorillonite suspension A .

1.0g degree of deacetylation is that chitosan of 92% is dissolved in the lactic acid solution of 200ml 1%, controls pH value at about 5.0, obtains solution B.

This chitosan of 9.0g is dissolved in the lactic acid solution of 300ml 2%, adopts NaOH to adjust pH value to be 5.0, obtains solution C.

Suspension A was heated to 70°C, solution B was added dropwise, stirred for 0.5 hours, solution C, 0.5 g of oleic acid and 0.5 g of epichlorohydrin were added dropwise, and reacted for 2 hours to obtain a composite material.

Measured according to the national standard (GB/4456-84), the dry and wet tensile strength of the chitosan/montmorillonite composite material, the dry and wet elongation at break are 81.1Mpa, 30.2Mpa, 22.3% respectively , 51.2%.

After the chitosan/montmorillonite composite material was soaked in hydrochloric acid solution with a pH value of 5.0-6.0 for 1 hour, the film sample of the composite material was basically insoluble and the morphology remained unchanged.

The swelling degree of chitosan/montmorillonite composite is 103%.

The detection methods of mechanical properties, acid stability and swelling performance are the same as in Example 1.

Example 4

Add 2.0g of potassium-based montmorillonite with a cation exchange capacity of 80meq/100g and a particle size of about 70μm, add 75ml of water, and stir at a speed of 200 rpm for 20 minutes to obtain a stable montmorillonite suspension A .

1.4g of chitosan with a degree of deacetylation of 92% was dissolved in 300ml of 0.5% oxalic acid solution, and the pH value was controlled at about 5.0 to obtain solution B;

8.6g of this chitosan was dissolved in 250ml of 1% oxalic acid solution, and the pH value was adjusted to 5.0 by using NaOH to obtain solution C.

Suspension A was heated to 60°C, solution B was added dropwise, stirred for 0.5 hours, solution C, 0.5 g of polyethylene glycol 400 and 0.5 g of glyoxal solution were added dropwise, and reacted for 2 hours to obtain a composite material.

According to the national standard (GB/4456-84), the dry and wet tensile strength of the chitosan/montmorillonite composite material, the dry and wet elongation at break are 81.6Mpa, 30.1Mpa, 22.5% respectively , 50.5%.

After the chitosan/montmorillonite composite material was soaked in hydrochloric acid solution with a pH value of 5.0-6.0 for 1 hour, the film sample of the composite material was basically insoluble and the morphology remained unchanged.

The swelling degree of chitosan/montmorillonite composite is 91%.

The detection methods of mechanical properties, acid stability and swelling performance are the same as in Example 1.

Claims (8)

1. the preparation method of a chitosan/Nano composite material of montmorillonite is characterized in that, comprises the steps:

0.5～30 part of polynite is added 900～10000 parts of water, stir, obtain montmorillonite suspension liquid A;

1～30 part of chitosan is dissolved in the acid solution, regulates pH value to 3～6, obtains solution B;

70～99 parts of chitosans are dissolved in the acid solution, regulate pH value to 3～6, obtain solution C;

Suspending liquid A is heated to 40～90 ℃, stirs slowly to drip solution B down, is incubated 0.5～2 hour, adds solution C, 1～5 part of softening agent and 1～5 part of linking agent, reacts 2～24 hours, makes matrix material, and the umber of each component is weight part.

2. method according to claim 1 is characterized in that, polynite is added water, stirs 0.3～1.0 hour with 200～1000 rev/mins speed.

3. method according to claim 1 is characterized in that, it is in 05～5% the acid solution that 1～30 part of chitosan is dissolved in weight concentration, obtain solution B, it is in 1～5% the acid solution, to regulate pH value to 4～6 that 70～99 parts of chitosans are dissolved in weight concentration, obtains solution C.

4. method according to claim 3 is characterized in that, described acid is at least a in formic acid, acetate, lactic acid, the oxalic acid.

5. according to each described method of claim 1～4, it is characterized in that polynite is that the sodium base of cationic exchange total volume 50～200meq/100g is or/and the potassium base montmorillonite.

6. method according to claim 5 is characterized in that, polynite is 70～120meq/100g for the cationic exchange total volume.

7. method according to claim 5 is characterized in that, the polynite particle diameter is 40～100 μ m.

8. according to the chitosan/Nano composite material of montmorillonite of each described method preparation of claim 1～7.

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