6.2.6: Hydrolysis of polymers Flashcards
What is hydrolysis?
- A chemical reaction in which water breaks bonds.
- For condensation polymers, hydrolysis is the reverse reaction of polymerisation- causing the polymer chains to breakdown into their constituent monomers.
Why do condensation polymers, such as nylon, not degrade when it rains and what can be used instead to degrade them?
- Hydrolysis of polyesters and polyamides with water has a very sloe rate of reaction.
- However, the reaction can be achieved in acidic or basic conditions and the rate can be increased further by heating the reaction mixture.
What happens when a polyester is reacted with a strong aqueous acid?
- The reaction produces a diol and a dicarboxylic acid.
- The acid hydrolysis of polysester has a slow rate of reaction.
What happens when a polyester is reacted with hot sodium hydroxide solution?
- The reaction produces a diol and the salt of the dicarboxylic acid.
- The rate of reaction is very fast.
Polyamides will undergo hydrolysis in acidic and basic conditions. Which reaction has the fastest rate?
-The rate of traction of acid hydrolysis is much faster than basic hydrolysis for polyamides.
What happens when a polyamides are reacted with a strong aqueous acid?
-The reaction produces a diammonium salt and a dicarboxylic acid.
What happens when a polyamides are reacted with hot sodium hydroxide solution?
-The reaction produces the diamine and the salt of the carboxylic acid.
What has controlling the rate of hydrolysis allowed us to do?
- Develop degradable polymers.
- Many have ester links hat can undergo hydrolysis and cause the breakdown of the polymer chains.
How can we make polymers more environmentally friendly?
- By researching into finding monomers from renewable sources rather than monomers derived from the non-renewable raw material, crude oil.
- One example is poly(lactic acid) a monomer extracted from the renewable resource, corn starch.
