Some molecules are very large and others are small. A single molecule is called a monomer – mono means one and mer is the suffix for unit. So, a monomer is a molecule of a single unit. If the prefix poly means many, then a polymer is a large molecule made up of many smaller units, which are joined together. Some polymers are made up of millions of monomers.
What can a polymer do? Polymers play a large role in our everyday lives. Synthetic polymers have a multitude of uses from something as simple as a Styrofoam coffee cups to plastics, adhesives, fabrics, paints, rubber, polyester, gelatin, or even a life-saving artificial heart valve. The world as we know it today could not exist without these long chains of molecules called polymers.
The superabsorbent diaper polymer, sodium polyacrylate, absorbs water by means of osmosis, the movement of water molecules through a semi-permeable membrane. In this instance, the polymer network acts like a semi-permeable membrane, letting only molecules of water pass through the membrane-like structure of the polymer. Larger molecules of other substances are stopped by the semi-permeable membrane. When the polymer comes in contact with water, the water molecules migrate from the outside of the polymer to the inside, causing the polymer to swell.What causes the water molecules to move inside the polymer? Water will rush into the polymer if the sodium ion concentration is greater inside the polymer than outside in the water. In the process of making the polymer in the laboratory, sodium ions, just like those found in table salt are chemically bonded to part of the polymer molecule. So, in pure water the sodium ion concentration is naturally greater inside the polymer than outside in the water and water rushes in trying to equilibrate the sodium ion concentration inside and outside the polymer. Although the polymer network has an elastic-like quality, it can only stretch so far. The amount of water that the polymer can absorb is determined by the elastic strength of the polymer.
Milk is mostly water, but it also contains vitamins, minerals, proteins, and tiny droplets of fat suspended in solution. Fats and proteins are sensitive to changes in the surrounding solution (the milk).
You are going to observe how the weak bonds that hold proteins in solution are altered; how fats cluster to form micelle causing motion; and how lipids break the cohesive bonds in water that create surface tension.
You are also going to compare this reaction in whole milk (abt 12% fat) and skim milk (abt 0 to 2% fat).