Sodium polyacrylate
Encyclopedia
Sodium polyacrylate, also known as waterlock, is a polymer
with the chemical formula [-CH2-CH(COONa)-]n widely used in consumer products. It has the ability to absorb as much as 200 to 300 times its mass in water. Acrylate
polymers generally are considered to possess an anionic charge. While sodium neutralized polyacrylates are the most common form used in industry, there are also other salts available including potassium
, lithium
and ammonium
.
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
with the chemical formula [-CH2-CH(COONa)-]n widely used in consumer products. It has the ability to absorb as much as 200 to 300 times its mass in water. Acrylate
Acrylate
The acrylate ion is the ion of acrylic acid.Acrylates are the salts and esters of acrylic acid. They are also known as propenoates ....
polymers generally are considered to possess an anionic charge. While sodium neutralized polyacrylates are the most common form used in industry, there are also other salts available including potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
, lithium
Lithium
Lithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. It is represented by the symbol Li, and it has the atomic number 3. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly...
and ammonium
Ammonium
The ammonium cation is a positively charged polyatomic cation with the chemical formula NH. It is formed by the protonation of ammonia...
.
Applications
Acrylates and acrylic chemistry have a wide variety of commercial and industrial uses that include:- Sequestering agents in detergentDetergentA detergent is a surfactant or a mixture of surfactants with "cleaning properties in dilute solutions." In common usage, "detergent" refers to alkylbenzenesulfonates, a family of compounds that are similar to soap but are less affected by hard water...
s. (By binding hard waterHard waterHard water is water that has high mineral content . Hard water has high concentrations of Ca2+ and Mg2+ ions. Hard water is generally not harmful to one's health but can pose serious problems in industrial settings, where water hardness is monitored to avoid costly breakdowns in boilers, cooling...
elements such as calciumCalciumCalcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
and magnesiumMagnesiumMagnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
, the surfactantSurfactantSurfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid...
s in detergents work more efficiently.) - Thickening agentThickening agentThickening agents, or thickeners, is the term applied to substances which increase the viscosity of a solution or liquid/solid mixture without substantially modifying its other properties; although most frequently applied to foods where the target property is taste, the term also is applicable to...
s - CoatingCoatingCoating is a covering that is applied to the surface of an object, usually referred to as the substrate. In many cases coatings are applied to improve surface properties of the substrate, such as appearance, adhesion, wetability, corrosion resistance, wear resistance, and scratch resistance...
s - Fake snowSnowSnow is a form of precipitation within the Earth's atmosphere in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. Since snow is composed of small ice particles, it is a granular material. It has an open and therefore soft structure, unless packed by...
- Super absorbent polymersSuperabsorbent polymerSuperabsorbent polymers are polymers that can absorb and retain extremely large amounts of a liquid relative to their own mass....
. These cross-linked acrylic polymers are referred to as "Super Absorbents" and "Water Crystals", and are used in baby diaperDiaperA nappy or a diaper is a kind of pant that allows one to defecate or urinate on oneself discreetly. When diapers become soiled, they require changing; this process is often performed by a second person such as a parent or caregiver...
s. Copolymer versions are used in agriculture and other specialty absorbent applications.The origins of super absorbent polymer chemistryPolymer chemistryPolymer chemistry or macromolecular chemistry is a multidisciplinary science that deals with the chemical synthesis and chemical properties of polymers or macromolecules. According to IUPAC recommendations, macromolecules refer to the individual molecular chains and are the domain of chemistry...
trace back to the early 1960s when the U.S. Department of AgricultureUnited States Department of AgricultureThe United States Department of Agriculture is the United States federal executive department responsible for developing and executing U.S. federal government policy on farming, agriculture, and food...
developed the first super absorbent polymer materials. This chemical is featured in the Maximum Absorbency GarmentMaximum Absorbency GarmentA Maximum Absorbency Garment is a piece of clothing NASA astronauts wear during liftoff, landing, and extra-vehicular activity to absorb urine and feces. It is worn by both male and female astronauts. Astronauts can urinate into the MAG, and usually wait to defecate when they return to the...
used by NASANASAThe National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
.
See also
- PolyacrylamidePolyacrylamidePolyacrylamide is a polymer formed from acrylamide subunits. It can be synthesized as a simple linear-chain structure or cross-linked, typically using N,N-methylenebisacrylamide. Polyacrylamide is not toxic...
, a cationic charged polymer used in straight-chain form or can be co-polymerized with acrylic acid and other monomers. In cross-linked form, these blended co-polymers can yield specialty superabsorbent polymers. - Polyacrylic acidPolyacrylic acidPoly or PAA or Carbomer is a type of anionic polymer. The monomer of poly is acrylic acid. In a water solution at neutral pH, many of the side chains of PAA will lose their protons and acquire a negative charge. This makes PAA a polyelectrolyte.Dry PAA is a white solid...