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DNA and RNA
Some of the most important polymers for life on Earth are natural polymers. DNA and RNA are two types of polymers. They are sets of directions that guide protein synthesis and cell metabolism. The nucleic acids contain three main compounds: pentose sugars --- which are five carbon atoms; phosphates --- which are salts from phosphoric acid; and heterocyclic amines --- which are compounds with at least one ring that has at least two different elements contained within it.
Protein
Proteins play a major role in the structure of animal and plant tissues. They are polymers that are made up of amino acids. Proteins can have anywhere from two to several thousand amino acids. The proteins have specific functions, but they cannot function properly unless they have the right sequence of amino acids. Amino acids are molecules mostly made up of oxygen, nitrogen, hydrogen and carbon.
Carbohydrates
Carbohydrates are the sugars, starches, polysaccharides and saccharides that provide energy to organisms. These include glucose, fructose, sucrose, lactose and cellulose. The cellulose plays a major role in plants, forming the cell walls that protect the contents of the plant cells. Sucrose is what is commonly called "sugar"; lactose is the substance that prevents lactose-intolerant people from consuming dairy products.
Rubbers and Elastomers
Conventional rubbers and elastomers contain three-dimensional elastic networks called "junctions." Junctions are heated until they reach a temperature where they experience thermooxidative degradation, which is when heat and oxygen break them down. They are rubbery at room temperature. They can be deformed and will return to almost their original shape.
Gels
Polymer gels are semi-solid materials with a jelly-like texture. Some gels, called "hydrogels," can dissolve in water. Smart gels change their volume, elastic properties and color depending on conditions such as temperature, pH, lighting and magnetic field.
Plastics
Plastics are polymers that will hold their shape after being molded under the right temperature and pressure conditions. They do not have reversible elasticity like rubber. Thermoplastics can be recycled and reused. They only change when subjected to high enough temperatures. Thermosets are harder and better for reinforcing other materials. They are used in fiberglass.
Adhesives
Polymer adhesives fuse objects together. How they cure varies. Anaerobic adhesives must be deprived of oxygen. Ultraviolet adhesives only cure when exposed to ultraviolet light. Anionic reactive adhesives turn into polymers when in contact with slightly alkaline substances. Some polymers require an additional substance that activates the adhesion.