Polymers Flashcards
What is condensation polymer?
A polymer produced by repeated condensation reactions between monomers.
Involves the elimination of a small molecule.
How can condensation polymers be identified?
The monomers are linked by ester or amide bonds.
How can condensation polymers be formed?
Condensation polymers can be formed by:
- dicarboxylic acids and diols
- dicarboxylic acids and diamines
- amino acids
How is a polyester formed and what are the bonds between monomers?
Formed by the reaction between dicarboxylic acid monomers and diol monomers.
Polyester is produced by linking these monomers with ester bonds.
What is an ester bond?
What is a diol?
A diol contains 2 -OH groups.
What is a dicarboxylic acid?
A dicarboxylic acid contains 2 -COOH groups.
What happens when the polyester is formed?
When the polyester is formed, one of the -OH groups on the diol and the hydrogen atom of the -COOH are expelled as a water molecule (H2O).
What is a hydroxycarboxylic acid?
They contain an alcohol group (-OH) at one end of the molecule while the other end is capped by a carboxylic acid group (-COOH).
Monomers of hydroxycarboxylic acids can be used to create a polymer via a condensation reaction where H2O is produced. They are joined by ester links like dicarboxylic acids and diols.
What are polyamides?
Polyamides are polymers where repeating units are bonded together by amide links.
How can we form a polyamide?
A diamine and a dicarboxylic acid are required to form a polyamide
- A diamine contains 2 -NH2 groups
- A dicarboxylic acid contains 2 -COOH groups
Dioyl dichlorides can also be used to react with the diamine instead of the acid
- A dioyl chloride contains 2 -COCl groups
- This is a more reactive monomer but more expensive than dicarboxylic acid
How do amino acids join together?
-NH2 on one amino acids joins with -COOH on another amino acid - forms ester bond.
Example of condensation reaction.
What is hydrolysis?
Hydrolysis is a breaking up of a molecules using water
What happens in acid hydrolysis in polyamides?
In acidic hydrolysis, acid (such as hydrochloric acid) acts as the catalyst.
Polyamides are heated with dilute acid.
This reaction breaks the polyamide into carboxylic acid molecules and ammonium chloride ions.
What happens in alkaline hydrolysis in polyamides?
The polyamide is heated with a species containing hydroxide ions (eg. sodium hydroxide).
This breaks the polymer into the sodium salts of its monomers (dicarboxylic acids and diamines).
If the poly amide link used an aminocarboxylic acid as the monomer, then a sodium salt of the original amino acid is reformed.
