Monomers used to make sodium polyacrylate polymer chains
The Correct Answer and Explanation is:
The monomer used to make sodium polyacrylate polymer chains is sodium acrylate.
Explanation:
Sodium polyacrylate is a superabsorbent polymer commonly used in products such as diapers, feminine hygiene products, and certain medical bandages. It is a polymer composed of repeating units (monomers) linked together through polymerization. The monomer that forms sodium polyacrylate is sodium acrylate, which is a salt formed from the neutralization of acrylic acid with sodium hydroxide.
- Acrylic Acid and Its Derivatives: The structure of acrylic acid (C₃H₄O₂) contains a carboxyl group (-COOH) and a vinyl group (-CH=CH₂), which makes it reactive and capable of forming polymers. Acrylic acid itself, when polymerized, results in polyacrylic acid, which has hydrophilic (water-attracting) properties due to the carboxyl group.
- Neutralization: In the case of sodium polyacrylate, the acrylic acid is neutralized with sodium hydroxide (NaOH), which replaces the hydrogen ion (H⁺) of the carboxyl group with a sodium ion (Na⁺), forming sodium acrylate. This results in the polymer chain having a negative charge along the backbone, which attracts and retains water molecules.
- Polymerization: The sodium acrylate monomers are polymerized through a chemical reaction where the double bond in the vinyl group (-CH=CH₂) is broken and new bonds are formed, linking the monomers together to form long chains of sodium polyacrylate. The polymerization process is often initiated by a free radical initiator, which causes the vinyl groups to react and create the polymer chains.
- Superabsorbent Properties: Sodium polyacrylate’s ability to absorb and retain large amounts of water is due to its negatively charged carboxylate groups, which can form ionic bonds with water molecules, enabling the polymer to swell and hold water in the polymer matrix. This makes sodium polyacrylate ideal for use in products that need to absorb liquids quickly, like diapers.
In summary, sodium acrylate is the monomer that polymerizes to form sodium polyacrylate, a polymer known for its exceptional water-absorbing properties.