Slide

Study on Water Resistance of Polyacrylic Acid Zinc Complex Film

Abstract:

A method for synthesizing a polyacrylic acid zinc complex in a redox initiation system by aqueous solution polymerization. Its solubility in water, ammonia, and ammonia/water mixtures was tested. It was found to be insoluble in water but soluble in ammonia and ammonia/water mixtures. The experimenters tested the contact angle of the solution on various substrates. The coating test on the glass surface was carried out. The effects of dissolving conditions, drying conditions and testing conditions on the film properties were studied. The results showed that the film had excellent water resistance and hydrophilicity, which could absorb a small amount of water.

Keywords:

Polymer metal complex, polyacrylic acid zinc salt complex, water solubility, water resistance, film coating.

Content

The material systems obtained by combining organic and inorganic polymer compounds with metal salts, metal complexes, metal chelates and metal clusters provide great potential for the development of material science.

The author defined macromolecular complexes as complexes composed of macromolecules, the typical representative of which is Macromolecule-Metal Complexes (MMC), and molecular aggregates are also included in the scope of macromolecular complexes. It can be said that the combination of polymer and metal produces many structural possibilities, which are further expanded by noting that the interaction between polymer compounds and metal derivatives can produce products with new structural characteristics and new static and dynamic characteristics in many cases.

Previous studies have focused on the exploration of gas transport, electronic interaction, catalysis, energy conversion and other functions of polymer-metal complexes [2 ~ 4]. In this paper, a kind of poly (zincacrylate) complexes (PZA) was prepared. It was found that PZA had certain hydrophilicity and could be dissolved in aqueous system. On the other hand, after its aqueous solution is coated and dried, it has excellent water resistance, although it can absorb a certain amount of water, it will not be dissolved, and it is a novel functional film.

Experiment Section

1.1 Raw materials

Acrylic acid (AA), zinc oxide (ZnO), ammonium persulfate ( (NH4) 2S2O8), sodium bisulfite (NaHSO3), ammonia water, hydrochloric acid and deionized water.

1.2 Synthesis

A certain amount of zinc oxide and a proper amount of hydrochloric acid are just completely reacted to obtain a zinc chloride solution. The prepared solution is added into the prepared acrylic acid, the pH value of the reaction solution is adjusted by ammonia water, the concentration of the reaction solution is adjusted by deionized water, a certain amount of ammonium persulfate and sodium bisulfite solution are added after the mixture is stirred to be uniform, the mixture is stirred to be uniform and placed in a water bath with the temperature of 60 deg C for reaction to obtain light yellow gel which is cut into pieces, And vacuumize and drying in a vacuum oven at 60 deg C, and crus.

1.3 Testing

1.3.1 Solubility

Weigh a certain amount of resin into sufficient deionized water and ammonia water and ammonia/water mixture respectively, and visually observe whether it dissolves or swells after 2 days.

1.3.2 Contact angle test of solution

Instrument model: JZHY-180 interface tensiometer. A sample to be teste is prepared into a solution with a certain concentration, that solution is drop on the surface of various substrates (aluminum, aluminum alloy, stainless steel and glass), and the contact angle is measured.

1.3.3 Membrane water resistance

(1) solution preparation. A certain amount of sample was dissolved in the mixed solvent of ammonia and water (1 ∶ 5), and then diluted with deionized water to different concentrations for coating test.

(2) Clean the surface of a 25 × 75mm glass slide.

(3) coating the prepared sample solution.

(4) the glass slide coated with the film is respectively subjected to three conditions: natural volatilization; The air in that fume hood is exhaust to accelerate volatilization; Dry in a humidifier. (The humidifier is to take out the desiccant from the ordinary dryer and replace it with water.)

And respectively soak or cooking in wat at different temperatures, and weighing that weight changes at certain time interval. The water resistance is expressed by the weight gain rate. Weight gain rate = (W2-W1)/W1, where W1 is the dry weight of the film and W2 is the weight of the film after soaking or cooking.

2 Results and Discussion

2.1 Solubility of zinc polyacrylate

Poly zinc acrylate (PZA) in three solvents: water, ammonia, and ammonia/water mixtures. It is found to be insoluble in water, but soluble in ammonia, and ammonia/water mixtures, and after dissolution, can be infinitely diluted with water. This shows that the so-called “ionic crosslinking” between zinc ions and carboxyl groups in polyacrylic acid does occur, which makes it only swell, but not dissolve. However, when the solvent is ammonia or contains ammonia, ammonia is easy to coordinate with zinc ions to form zinc-ammonia complexes, which leads to the destruction of the “crosslinking” of zinc ions and dissolution.

2.2 Contact angle of zinc polyacrylate solution on different substrates

As a coating application, the wettability between the solution and various substrates is a very important indicator, so we tested the contact angle of the solution of the polyacrylic acid zinc complex on various substrates, as shown in Figure 1. As can be seen from Figure 1, it has the best wettability on the glass surface. This may be due to the existence of a large number of hydroxyl groups on the glass surface, which can form hydrogen bonds with ammonia and increase the wettability. In addition, the concentration also has a certain effect on the contact angle. Fig. 2 shows the contact angle of PZA solution with different concentrations on the glass surface. At first, the contact angle increases with the increase of the concentration, indicating that the wettability becomes worse. When the concentration is 0.06 G/ml, the contact angle reaches the maximum, and then decreases with the increase of the concentration.

2.3 Water resistance of coating film

2.3.1 Effect of the concentration of the prepared solution

The weight change of PZA solutions prepared at different concentrations after coating and treatment in water at 80.d egree. C. Each film absorbs water to a certain extent as the treatment time in water increases, but does not dissolve. Among them, the weight of the film coated at a concentration of 2.5% (G/ml) was reduced during the water treatment process, which was due to the poor adhesion of the film and the partial damage and peeling off. When the solution is prepared, the concentration of 3.3% is more suitable, because the molecular weight of the polyacrylic acid zinc complex is larger, and if the concentration is too large, the solution is not easy to be completely dissolved, and the obtained film is not uniform and is easy to generate defects; If the concentration is too small, a large number of voids will be left on the film with the volatilization of the solvent, which will also affect the adhesion and water resistance of the film.

2.3.1 Effect of the concentration of the prepared solution

The weight change of PZA solutions prepared at different concentrations after coating and treatment in water at 80.d egree. C. Each film absorbs water to a certain extent as the treatment time in water increases, but does not dissolve. Among them, the weight of the film coated at a concentration of 2.5% (G/ml) was reduced during the water treatment process, which was due to the poor adhesion of the film and the partial damage and peeling off. When the solution is prepared, the concentration of 3.3% is more suitable, because the molecular weight of the polyacrylic acid zinc complex is larger, and if the concentration is too large, the solution is not easy to be completely dissolved, and the obtained film is not uniform and is easy to generate defects; If the concentration is too small, a large number of voids will be left on the film with the volatilization of the solvent, which will also affect the adhesion and water resistance of the film.

2.3.1 Effect of the concentration of the prepared solution

The weight change of PZA solutions prepared at different concentrations after coating and treatment in water at 80.d egree. C. Each film absorbs water to a certain extent as the treatment time in water increases, but does not dissolve. Among them, the weight of the film coated at a concentration of 2.5% (G/ml) was reduced during the water treatment process, which was due to the poor adhesion of the film and the partial damage and peeling off. When the solution is prepared, the concentration of 3.3% is more suitable, because the molecular weight of the polyacrylic acid zinc complex is larger, and if the concentration is too large, the solution is not easy to be completely dissolved, and the obtained film is not uniform and is easy to generate defects; If the concentration is too small, a large number of voids will be left on the film with the volatilization of the solvent, which will also affect the adhesion and water resistance of the film.

2.3.2 Influence of drying conditions on film performance

The film was volatilized under the conditions of natural volatilization, accelerated volatilization in a fume hood and slow volatilization in a humidifier, and it was found that the performance of the film was also closely related to the drying conditions. When the volatilization speed is fast, the formed film is compact and uniform, has strong adhesive force, and is not easy to be destroyed during boiling; However, the sample volatilized slowly in the humidifier fell off seriously after boiling for 3 H.

2.3.3 Effect of test water temperature

The water resistance test of the membrane was carried out in water at 100 ℃ and 80 ℃ respectively, and it was found that the membrane was easy to break and fall off when treated in water at 100 ℃, because the adhesion between the membrane and the glass was not very strong, and the boiling water had a constant scouring force on it, so it was easy to fall off, but even the fallen membrane did not dissolve in boiling water. The water absorption of the membrane is quite stable after treatment in water at 80.d egree. C.

Conclusion

(1) The polyacrylic acid zinc complex was prepared, and it was found that the polymer could be dissolved in aqueous system, and the formed solution film had excellent water resistance after drying.

(2) When the concentration of the prepared solution is 3.3%, the film performance is the best by natural volatilization or slightly accelerated volatilization. The more severe the test conditions are, the less the water resistance is affected, but the film is more easily damaged and falls off.

The product can be used for: (1) ecological protection of plants. Uch as insect resistance, disease resistance and drought resistance; (2) paint; (3) Building materials. As an additive for cement; (4) Others.