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Polymers-Osmosis Magic (Bob Fiero)

Demonstrator:  Bob Fiero

Poly-sorb or Sodium Polyacrylate is an amazing polymer that absorbs 100-500 times its weight in water. A blend of polyester and super water-absorbent polymer fibers.

 

What does an astronaut do if they are in the middle of a space walk when they need to go to the bathroom? Diapers, that's right they wear an adult size diaper with a super absorbent chemical called poly-sorb. Space is not the only place that poly-sorb is being used. You can find poly-sorb in disposable diapers. It is spread throughout the cotton lining. Poly-sorb is also being used in environmental clean-ups.

It is effective in removing the following toxins from waste streams as a petroleum purifying agent: arsenic, jet fuel, paints, gasoline, diesel fuel, pesticide, mercury and many others. It is listed on the EPA National Contingency Plan for use in emergency response situations.

 

You will need:

  • One packet of sodium polyacrylate - you can buy it  as "InstaSnow" like from Steve Spangler Science or in garden centers as 'Water Retaining Gel'.
  • Two cups. Make sure you can dispose of the cups afterwards.
  • Some water.
  • A tablespoon.

What you do:

  1. Put a tablespoon of the powder in the bottom of one cup.
  2. Pour some water into each of the cups.
  3. Swish the water around in each cup and turn them upside down (you might want to do this over a sink because at least one of your cups will spill).
  4. Poke and prod the gel in the bottom of the cup with a spoon.

What's going on?

The water retaining gel is sodium polyacrylate. It is an organic chemical, a polymer made up of a long chain of carbon, hydrogen, oxygen and sodium atoms. Sodium polyacrylate is a polymer, meaning that it consists of chains of identical units (monomers). The polymer looks like this &

CH2--CH(CO2Na)--

... over and over again. Have a look at the diagram of the formula.

On its own this polymer is wound up tightly. When water is added the sodium breaks off, dissolving in the same way that salt (sodium chloride) dissolves in water. The sodium is a positively charged ion, and what remains, the carboxyl ion (attached to the rest of the polymer), is negatively charged. Because all the negatively charged carboxyl ions on the polymer repel each other, the whole polymer starts to unwind.

In a water molecule (H20) the oxygen atom attracts the two hydrogen atoms' electrons, leaving the hydrogen atoms slightly positive and the oxygen atom slightly negative: this is the water molecule's polarity. The oxygen side of the water molecules is attracted to the positive sodium ions from the sodium polyacrylate polymer. At the same time, the hydrogen atoms in the water molecules are attracted to the carboxyl groups of the polymer. The polymer has some cross links - so instead of a perfectly long line, the polymer forms a spread out net with water molecules held within it.

Adding other ions to the mix, such as salt, disrupts how the water is held in the gel. Adding salt to the gel turns it back into a watery liquid.

Special safety advice

Do not try and drink the liquid / gel, and don't use the cups after performing the experiment. Do not dispose of the gel down a sink as it may cause a blockage.

Uses of the material:

Interestingly it can be recycled to make Hydroweave ‘performance enhancing’ fabrics. Produced  by  AquaTex this newly patented evaporative cooling technology provides a versatile composite fabric to be used in a wide variety of consumer and industrial heat stress cooling apparel applications.

  • Soaking Hydroweave in water for five minutes activates the cooling process * Hydroweave’s advanced fibrous batting (PolySorb, AraSorb) captures and evenly distributes water throughout the entire garment. Because Hydroweave has a finite water absorption capability - it cannot be over soaked.
  • As water evaporates from Hydroweave’s fibrous batting it actively cools the wearer while its shell and lining keep the wearer dry and comfortable.
  • Cools ‘dry’ without the feel of moisture or gelatin.
  • Delivers up to eight hours of cooling comfort.
  • Easily reactivated.
  • Thermally conductive, wickable inner lining allows body heat to escape.
  • Hydroweave is available in a variety of outer shell fabrics and colors to support a wide range of applications.
  • Garments made of Hydroweave are rugged, reusable, and machine-washable.
  • Flame-Resistant Hydroweave is available for protection from flame and as a barrier to radiant heat sources.
  • Meets or exceeds NFPA, SFI, and TPP specifications.
  • Can be used to construct a variety of products without the limitations of loose granular polymers, ice-packs, phase change or capillary products.

Since 2003, OAO Dubrovskiy Stud Farm has used the enterosorbent Polysorb VP for prevention and treatment of gastrointestinal tract deseases, acute poisoning in fattening calves (at the commercial unit).  Polysorb VP has eliminated dyspepsia in animals, terminated mycotoxicosis, significantly improved biochemical blood indices, and increased body resistance.Calves received for fattening (from different companies) acquire normal condition much faster. Polysorb VP is the only Russian enterosorbent developed on the basis of nanobiotechnology; it has high adsorbing properties that ensure fast detoxication at internal or external application.

The class of materials known as superabsorbents have been used for converting liquid medical wastes into a gelled or solidified form for disposal. A granular superabsorbent is added to the medical waste, which may be an inadvertent spill or a containerized waste, such as blood or body fluids.

For disinfecting and gelling medical wastes, antimicrobial agents have been used in combination with the superabsorbents. However, a number of practical problems have been encountered in the use of such absorbent/disinfectant mixtures. It is desired to gel the liquid waste while at the same time effectively disinfecting the gelled body throughout its mass. Heretofore, these combined objectives have not been adequately achieved.When a mixture of a disinfectant powder and a granular absorbent is added to a containerized liquid waste it settles to the bottom before the gellation takes place. The superabsorbent granules then swell and distribute upwardly until the entire liquid is converted to gel form. However, the disinfectant tends to stay in the bottom portion of the container and is not effectively distributed throughout its upper portions. The resulting gelled body, consequently, has an uneven distribution of the disinfectant. One ounce of the product can solidify and disinfect up to about 1500 milliliters of liquid waste, i.e. one part powder solidifies about fifty parts liquid (w/v). For example, a one ounce pre-measured quantity can be added to a liquid waste in a 1500 ml suction canister. Most of the mix will fall to the lower portion of the container, and then the liquid waste will be rapidly converted to a gelled body by the expansion of the polymer granules, which proceeds from the bottom to the top of the container. The glutaraldehyde disinfectant is distributed throughout the mass of the gelled body for effectively disinfecting the entire body. This distribution can be observed by the yellow color of the gelled material.

Polysorb makes for a great special effects used in the entertainment industry!  It is used as fake (unmelting) snow and mashed potatoes that will not spoil for those long shoots. You can buy it as the product "InstaSnow."

Have fun!

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