I believe everyone has played with such a toy when they were children. We call it " Ocean Baby ". When we buy the Ocean Babies, they are colorful beads. After we soak them in water for a while, we will be surprised. I found that the beads would "grow" more than ten times, became soft and elastic when pinched, and were not easily crushed. However, such a mediocre toy often appears in the news about children's accidents. Due to accidental ingestion by children, its expansion characteristics may cause children to suffer from respiratory obstruction or intestinal obstruction . It has been listed as a toy with high safety hazards. ranks[1]. After checking the information, it turns out that "Ocean Baby" belongs to super absorbent resin . Next, let's go into the world of chemistry and see what super absorbent resin is.
picture 1. before and after absorbing water " Ocean Baby " ( picture comes from the Internet )
super absorbent resin (SAP) is a water-swellable function that is neither soluble in water nor insoluble in organic solvents. High molecular polymer, the molecular chain contains hydroxyl (-OH), carboxyl (-COOH) amide group (-CONH2), sulfonic acid group (-SO3H) and other hydrophilic groups and a loose network structure. [2] It has super adsorption capacity and can absorb hundreds to thousands of times of water than its own weight. When it absorbs water and swells, it solidifies with water and becomes a kind of hydrogel , which has fast water absorption rate and water retention properties. Good to wait for the advantages. The reason why
has such a powerful function is that the material has hydrophilic genes such as carboxyl and hydroxyl groups that interact with the hydrogen bonds in water molecules, and its molecular chain grid structure can be highly swollen, holding water molecules tightly. It is tightly bound, and the liquid is still difficult to squeeze out under conditions of heat and pressure. In addition, when the surrounding environment is relatively dry, the absorbed liquid can be slowly released. Because of SAP's special and excellent characteristics, it has been widely used in sanitary products, agriculture and other fields.
In recent years, SAP has developed rapidly and has abundant sources of raw materials. According to raw materials, it can generally be divided into three categories: synthetic polymers, biomass (starch, cellulose, etc.), and organic-inorganic composites [3] . Synthetic polymer water-absorbing resin is obtained by cross-linking small molecules with polymer parts. The main raw materials include polyvinyl alcohol (PVA), polyacrylate (PAA), polyacrylamide (PAM) Among them, PAA raw materials are simple and easy to obtain, have good heat resistance, good resistance to most acids and alkalis, and are not easy to be corrupted during long-term storage. It is precisely because of its good performance that it has become the most researched and most applied at present. Wide variety.
However, this kind of water-absorbent resin is difficult to biodegrade and easily pollutes the soil. Therefore, the search for degradable water-absorbent materials has become another hot spot for researchers. Biomass-based water-absorbent resins have exactly this kind of performance, and their raw materials There are natural products such as starch, cellulose, protein, chitosan , citric acid , etc. The raw materials of this type of water-absorbent resin are low-cost and easy to obtain, and can be biodegraded, which greatly reduces environmental pollution. Therefore, , has great prospects in agricultural production. Organic-inorganic composite water-absorbing resins are designed to solve the shortcomings of traditional SPA that have strong water absorption capacity, but poor mechanical properties, salt resistance and repeated swelling ability. Therefore, the superior properties of nanomaterials can be used to combine inorganic nanomaterials. Add organic SPA for modification to improve the stability, mechanical properties, salt resistance and other comprehensive properties of water-absorbing material .
Applications of super absorbent resin in daily life
1, application in cosmetics
Super absorbent resin materials can be used as additives in cosmetics, thickeners , hair dyes, etc. The addition of this material in cosmetics has certain Moisturizing effect, for example, in some cosmetics, in order to achieve a cooling effect, alcohol is added to the cosmetics, and alcohol is volatile. Adding a certain amount of super absorbent resin to it can prevent volatilization.Secondly, the resin after absorbing water is in gel form with good viscosity and can be used as a thickening agent for cosmetics. In daily life, people often dye their hair in order to make themselves look young and fashionable. In industry, hair dyes prepared from polyacrylate super-absorbent resin, nail cellosolve, acid dyes and water are often used, and super-absorbent resin is added. It can make the materials more integrated and have a certain hair care effect, and the dyeing effect shown will also be improved.
The most commonly used carrier material in cosmetics is super absorbent resin. In addition to the above applications, people can attach nutrients or drugs and other substances in SAP, so that nutritional cosmetics and pharmaceutical cosmetics can be made, making the cosmetics have Certain effects can better meet people's daily needs.
2. Application in agricultural production
SAP has excellent performance in absorbing water, retaining water and retaining fertilizer, so it has important applications in agricultural production. In drought and water-deficient environments, it can be used as a water-retaining agent to treat soil [4], allowing the soil to maintain a higher moisture content for a longer period of time, greatly improving the water utilization rate, and achieving the greatest economic effect. SAP is used in It can absorb a large amount of water when the water is abundant, and slowly release water during drought. It can excellently conserve rainwater, which not only reduces the number of irrigations, but also saves irrigation costs. Super absorbent resin can also improve the soil and promote the formation of soil aggregate structure. These aggregates can stabilize the soil structure, improve soil permeability, greatly slow down the evaporation of the soil surface, and the soil's anti-erosion ability is also significantly improved. of enhancement. Since SAP has the function of absorbing and retaining water and fertilizer, people often use water-absorbent resin to wrap or complex the fertilizer to slowly release the fertilizer. Under the same water and fertilizer conditions, this method not only increases crop yields, but also improves fertilizer utilization. .
3. Other applications
In daily hygiene products, SAP can be used in common physiological products, such as sanitary napkins, diapers, etc., providing great convenience to people's lives. It can also be used in deodorants and fragrance products. For example, when making solid fragrances, you can mix an appropriate amount of SAP and glycerol , and then add a certain amount of spices after solidification to obtain a solid fragrance with good performance. agent. In addition, during the transportation of fresh food, fresh food itself contains a lot of water, and it is easy to lose moisture after contact with dry air, and the longer the fresh food is stored, the more likely it is to deteriorate. In order to improve the shelf life of fresh food, preservatives formulated with SAP and propylene glycol with antibacterial effects can be used to preserve the food and extend the storage time of the food.
picture 2. PVA film (picture source network)
With the continuous development of science and technology, super absorbent resin has been widely used in daily life, and then every magical functional material has its pros and cons. We must learn to dialectically Using these materials, while continuing to conduct in-depth research, we must also promptly solve the problems discovered, so that we can better build our beautiful earth home.
