Water Absorption Mechanism And Development Direction Of Super Absorbent Polymer Powder

Super absorbent polymer powder is a new type of functional polymer material. Because of its strong water absorption and excellent water retention, it is widely used in many fields such as industry and sanitation. In this paper, the water absorption mechanism of super absorbent polymer powder is introduced, and its development direction is prospected.

1. Water absorption mechanism of super absorbent polymer powder

Super absorbent polymer powder can not only absorb a lot of water, but also its water retention performance is quite strong. After absorbing water, there are three kinds of interactions between it and water: (1) the water molecule forms hydrogen bonds with the oxygen atom with strong electronegativity in the polymer; (2) the interaction between the water molecule and the hydrophobic group; (9) the interaction between the water molecule and the hydrophilic group. interaction.

There are three kinds of water around its hydrophilic group: bound water, bound water, and free water. Among them, bound water is mainly water bound on the inner and outer surfaces of the gel through solvation, coordination bonds or hydrogen bonds, and bound water is another kind of water connected with bound water through hydrogen bonds or orientation force. The same as liquid water, a large amount of free water is stored in the network of the water-absorbent resin mainly by the three-dimensional space network of the polymer.

In the initial stage, the water absorption rate is very slow, because the water absorption at this time is achieved by capillary adsorption and dispersion, and then the water molecules interact with the hydrophilic groups of the resin through hydrogen bonds to dissociate, and the anions are fixed in the polymer chain. , the cations are free to move. With the further dissociation of the hydrophilic groups, the number of anions increases, and the electrostatic repulsion between the ions expands the resin network; at the same time, in order to maintain electrical neutrality, the cations cannot diffuse to the external solvent, resulting in an increase in the concentration of cations in the resin network. . As a result, osmotic pressure is generated inside and outside the network, and moisture further penetrates. With the increase of water absorption, the osmotic pressure difference inside and outside the network tends to zero; while the network expands, its elastic contraction force also increases, gradually offsetting the electrostatic repulsion of anions, and finally reaching a water absorption balance.

2. Development direction of super absorbent polymer powder

① Develop super absorbent resin with good salt resistance and expand the scope of application. Grafting monomers containing nonionic, zwitterionic groups can be used

group or the introduction of amino and sulfonic acid groups and other methods.

②At present, more than 90% of the domestic research on it is related to product development, and there are very few researches involving basic theory. In the future, efforts should be made in basic theory to guide the direction of work.

③ Research and develop a new type of composite super absorbent resin. The composite material prepared by physically mixing inorganic or organic materials with it or participating in the polymerization reaction can not only improve the water absorption performance, salt resistance and water retention performance of the resin, but also reduce the cost.

④ It is one of the current research hotspots to adopt new initiation methods, especially microwave radiation method, ultraviolet radiation method and ultrasonic radiation method, and realize its industrial production.

⑤ Improve the process route. The research and development of natural water-absorbing agent is carried out under the condition that people's awareness of environmental protection and resources are continuously enhanced. It is in line with the world's development trend of developing green process products and pursuing environmental friendliness. Natural plant functional polymer material products, the raw materials are taken from nature, and the products are biodegraded and returned to nature. If such products can be developed in accordance with market demand, there will be good application prospects.

Super absorbent polymer powder, also known as hydrogel and super water absorbent, has become an important polymer material in recent years by virtue of its peculiar water absorption capacity and water retention capacity. Understanding the water absorption mechanism and development direction of super absorbent polymer powder will help people to better apply this material.