By: Jordan Storey & Tomy Nicholson

NATURAL POLYMERS

The word polymer originates from the two Greek words: “poly” and “meros”.

“Poly” translates to many, and “meros” translates to parts.

Therefore, a polymer is a molecule that is composed of multiple parts.

ORIGIN OF THE WORD POLYMER

A polymer is a long chain of thousands of identical “unit molecules” called monomers.

A natural polymer is a polymer that is found in nature and is not man made all natural or organic polymers come from living organisms.

WHAT IS A NATURAL POLYMER?

Monomer: A simple molecule that joins with others to create a long complex chain called a polymer.

Polymerization: The process of producing a polymer from monomers. (Bonding).

Addition Reaction: a reaction that creates polymers in which an unsaturated monomer becomes saturated. (It loses the double bond). (This will be explained in the next slide).

Condensation Reaction: polymers are formed by monomers who bond front to end. The product of this reaction is usually water. (This will be elaborated later in the presentation).

Functional Group: a specific arrangement of atoms that characterise chemical reaction in organic chemistry. (This is a way of classifying organic compounds).

KEY TERMS TO UNDERSTANDING POLYMERS

This diagram shows two ethene monomers, that form one polythene polymer. This is an addition reaction.

(*Notice the double bonds are lost to continue the polymer chain).

DEFINITION ADDITION REACTION EXPLANATION PHOTOS/DIAGRAM

Now we will discuss three chemists responsible for the advancement of chemistry involving polymers.

CHEMISTS WHO CONTRIBUTED TO THE SCIENCE OF NATURAL

POLYMERS

In 1861 Thomas Graham, a British Chemist realized that organic compounds such as starch and cellulose would not pass through fine fi lters, and that they could not be purified into crystalline form. He believed the organization of the atoms in these compounds to be completely diff erent from any other.

THOMAS GRAHAM

Thomas Graham

In 1920 Herman Staudinger researched polymers. He determined that polymers are composed of long chain molecules. These molecules are either identical or closely related. This discovery became the fundamental description of a polymer’s form. He later became the fi rst polymer chemist to win a Nobel Prize.

HERMAN STAUDINGER

Herman Staudinger

In 1928 Kurt Meyer and Herman Mark demonstrated the existence of polymers by examining their crystalline structures with x-rays. These findings helped Staudinger’s findings have more credibility.

KURT MEYER & HERMAN MARK

Herman Mark

Since natural polymers are natural they are found in nature. The human body, plants, food, and many other living beings.

WHERE CAN THEY BE FOUND?

On the following slides are some examples of natural polymers.

EXAMPLES

Starch- is a polymer formed of thousands of glucose monomers. As it is being formed it produces water molecules. Starch is a carbohydrate and is therefore found in a variety of foods such as cereal grains and potatoes.

STARCH

Cellulose- is the most common natural, (organic) compound on earth. This polymer is the base of which plants are made of, (their stems, leaves and the trunks of trees to name a few examples. It is also composed mainly of glucose, However the difference is made by the bonding arrangement.

CELLULOSE

Proteins- a common example would be DNA. They are formed by the bonding of amino acids. Proteins are linked by peptide bonds, which will be discussed later in the presentation.

PROTEINS OR POLYPEPTIDES

There are diff erent types of bonds found in polymers in the following slides we will look at a few examples.

BONDING EXAMPLES

Peptide Bonds are formed by the joining of a large quantity of amino acid units. The product of peptide bonds are called polypeptides. All protein molecules are polypeptides. This reaction produces water as a by-product and is therefore a condensation reaction.

PEPTIDE BONDS

This bond is when two sulfur atoms, from two monomers that bond together.

In this case hydrogen is the product, in addition to the polymer.

DISULFIDE BONDS

These bonds occur between the O, (oxygen) and H, (hydrogen) molecules of two monomers.

HYDROGEN BONDS

Negative charged side chains attract to positive charged side chains. (See the diagram below).

SALT BRIDGE

Amino acids are the monomers in protein polymers.

All amino acids except one of the twenty have the same general form.

Amino acids have side chains that determine their form.

INFO ON AMINO ACIDS BONDING

EXAMPLES OF AMINO ACIDS 1/3

EXAMPLES OF AMINO ACIDS 2/3

EXAMPLES OF AMINO ACIDS 3/3

Since we know that polymers can contain thousands of monomers, this becomes a seemingly overwhelming task.

However when drawing the structure or writing the formula we do not focus on the entire polymer. But only on a small part of it. This is the part that is repeated throughout the polymer.

HOW TO DRAW THE STRUCTURE

Draw the monomer structure.Put the brackets around the monomer. (Also notice

that the monomer loses the double bond).Place horizontal lines on the brackets, (this

symbolizes that the monomer is bonded to other identical monomers).

Place either a subscript n or the number of polymer links, (if known) outside the brackets.

STRUCTURE

The naming for polymers is rather simple, they follow the same general rule.

Poly(name of monomer)Certain polymers have more than one

monomer, but it follows the same rule.(There are some exceptions to this rule,

some polymers have more than one name).

NAMING

Monomer NameMonomer Structure

Polymer NamePolymer Structure

Polymer Uses

ethene (ethylene)CH2=CH2

polyethene

 (polythene or polyethylene)-[-CH2-CH2-]n-

LDPE for sandwich wrap, cling wrapHDPE for water pipes, wire insulation

propene (propylene)CH2=CHCH3

polypropene (polypropylen

e)-[-CH2-

CHCH3-]n-

electrical appliances, automotive applications, ropes, carpets, films

chloroethane (vinyl chloride)CH2=CHCl

polyvinyl chloride (PVC)-[-CH2-CHCl-]n-

indoor electrical conduit, underground water pipes

EXAMPLES OF POLYMER NAMES

Vinyl is an ethene which has 3 hydrogen atoms and 1 bond ready to take on a functional group, (substituent).

WHAT IS VINYL

When writing the formula:1. Identify the monomer.2.Use brackets with bonds coming off each side.3. Put n outside of brackets, (as a subscript), or the

number of monomers, (if known).Example: (See next slide)

HOW TO WRITE THE FORMULA

EXAMPLES OF FORMULA

The human body has approximately 100 000 diff erent proteins. All of these proteins are made of only 20 diff erent amino acids, (which are polymers).

Polyisoprene, is a polymer harvested from tropical plants. An example would be the rubber tree, (Hevea brasiliensis). The sap from the tree is more commonly known as latex.

INTERESTING FACTS ABOUT NATURAL POLYMERS

Polyisoprene

Great Document: http://preparatorychemistry.com/Bishop_Book_17_eBook.pdf

Great Website:http://www.britannica.com/EBchecked/topic/468696/polymerGreat Text Book:General Chemistry Principles & Modern Applications Sixth Edition-Petrucci Harwood-ISBN 0-02-394931-7Great Video:http://www.youtube.com/watch?v=KAruoKzTwfU

GREAT RESOURCES

http://www.youtube.com/watch?v=IkT7cxDsstI –A world Without Natural Polymers (3:21)

http://www.youtube.com/watch?v=KAruoKzTwfU –General Explanation (3:11)

VIDEOS

QUESTIONS?