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Sodium polyacrylate (ACR, ASAP, or PAAS), [1]: 233 also known as waterlock, is a sodium salt of polyacrylic acid with the chemical formula [−CH 2 −CH(CO 2 Na)−] n and has broad applications in consumer products.
Polyacrylic acid is a weak anionic polyelectrolyte, whose degree of ionisation is dependent on solution pH. In its non-ionised form at low pHs, PAA may associate with various non-ionic polymers (such as polyethylene oxide, poly-N-vinyl pyrrolidone, polyacrylamide, and some cellulose ethers) and form hydrogen-bonded interpolymer complexes. [17]
A SAP's ability to absorb water depends on the ionic concentration of the aqueous solution. In deionized and distilled water, a SAP may absorb 300 times its weight [4] (from 30 to 60 times its own volume) and can become up to 99.9% liquid, and when put into a 0.9% saline solution the absorbency drops to approximately 50 times its weight.
PSS is a 'strong' polyelectrolyte (fully charged in solution), whereas PAA is 'weak' (partially charged). Polyelectrolytes are polymers whose repeating units bear an electrolyte group. Polycations and polyanions are polyelectrolytes. These groups dissociate in aqueous solutions (water), making the polymers charged.
Acrylates (IUPAC: prop-2-enoates) are the salts, esters, and conjugate bases of acrylic acid.The acrylate ion is the anion CH 2 =CHCO − 2.Often, acrylate refers to esters of acrylic acid, the most common member being methyl acrylate.
Structure of a polyacrylate polymer. An acrylate polymer (also known as acrylic or polyacrylate) is any of a group of polymers prepared from acrylate monomers. These plastics are noted for their transparency, resistance to breakage, and elasticity. Acrylate polymer is commonly used in cosmetics, such as nail polish, as an adhesive. [1]
Water-reactive substances [1] are those that spontaneously undergo a chemical reaction with water, often noted as generating flammable gas. [2] Some are highly reducing in nature. [ 3 ] Notable examples include alkali metals , lithium through caesium , and alkaline earth metals , magnesium through barium .
Solution polymerization is a method of industrial polymerization. In this procedure, a monomer is dissolved in a non-reactive solvent that contains a catalyst or initiator. The reaction results in a polymer which is also soluble in the chosen solvent. Heat released by the reaction is absorbed by the solvent, reducing the reaction rate.