6.2.3 Polyesters and Polyamides

list the two types of polymers

• addition

• condensation

how do addition polymers form

when unsaturated alkene monomers react to form long saturated alkane chains.

conditions required to make addition polymers

• high temperature

• high pressure

• catalyst

give the balanced equation for formation of a poly(alkene)

• monomer, no brackets

• bond sticking out of brackets in polymer

• n to the right in the polymer

draw a Poly(alkene) with 3 monomers

• always draw bonds going out of brackets

• always have 2 carbons in one monomer (other carbons go on top/bottom)

• 3 monomers = 6 carbons in polymer

how many carbons in one monomer

2 (the others go on the top or bottom)

Why are poly(alkenes) non-biodegradeable

they are chemically inert:

• many strong C-C and C-H bonds

• bonds are non polar

list the types of condensation polymers

• polyesters

• polyamides

difference between condensation and addition polymers

• C also forms a small molecule (usually water), A only form the polymer

• C have monomers with 2 FG that are both broken; A only have monomers with alkene functional group that are broken

give the FG in polyesters

• carboxylic acid

• alcohol

give the FG in polyamides

• carboxylic acid

• amine

why just monomers in condensation polymers have 2 FGs

in order to continue making the polymer chain

two different ways polyesters can be made

• 2 monomers containing both COOH and OH functional groups (hydroxycarboxylic acids)

• 2 monomers, 1 with 2 COOH groups and 1 with 2 OH groups

what’s a hydroxycarboxylic

a compound with both OH and COOH groups

what bond is formed in a polyester

ester bond

how is an ester bond formed when making polyesters

The COOH group in one monomer reacts with the OH group in another monomer, forming ester bond and water

polymers made from two different monomers

• one monomer is a diol

• one monomer is a dicarboxylic acid

how to draw repeat units of polyesters

• amide bonds in middle

• remove OH from carboxylic acid end so CO—

• remove H from alcohol end so O—

draw a polymer with 3 repeat units or this monomer

draw 2-hydroxyprooanoic acid in monomer form

• put FGs at left and right

give two ways polyesters can be hydrolysed

• acidic conditions

• basic conditions

acidic hydrolysis of polyesters

• water is the reagent

• produces alcohol and carboxylic acid

give the acid hydrolysis of this

give the repeat unit of this

repeat units don’t have

• n

• or brackets

→ n alcohol and n carboxylic

polyester + water →

(water is the reagent in acid hydrolysis)

basic hydrolysis of polyesters

• the base is the reagent

• produces alcohol and carboxylate

what is the reagent in acid hydrolysis of polyesters

water

what is the reagent in basic hydrolysis of polyesters

the base

products of acid hydrolysis of polyesters

• carboxylic acid

• alcohol

products of basic hydrolysis of polyesters

• salts of dicarboxylic acid

• diols

polyester + NaOH

→ alcohol + sodium salt of carboxylic acid

polyester + NaOH

monomers needed to make polyamides

• diamines

• dicarboxylic acid

diamine + dicarboxylic acid →

→ polyamide + water

what bonds are formed when making polyamides

amide

how many water molecules are formed when making polyamides

(n-1) H2O

(number of amide bonds there are = number of water molecules)

draw a repeat unit of a polyamide

• O=C— (bond sticking out)

• HN— (bond sticking out)

how can we make polyamides from one monomer

by using amino acids (they have both COOH and NH2 group)

when amino acids make polymers what are they called

polypeptide / proteins

draw the polymer with 3 repeat units made from this monomer

two ways we can hydrolyse polyamides

• heating with aqueous acid

• heating with aqueous base

acidic hydrolysis of polyamides

• acid is the reagent

• produces carboxylic acid and ammonium salts (-NH3+) of the amine group

what is the reagent in acidic hydrolysis of polyamides

acid

(not water since we have a basic group that can react with the acid)

products of acidic hydrolysis of polyamides

• carboxylic acid

• ammonium salts (-NH3+) of the amine group

give the acid hydrolysis of this

basic hydrolysis of polyamides

• base is the reagent

• produces amines + carboxylates (salts of carboxylic acid group)

what is the reagent in basic hydrolysis of polyamides

the base

what are the products of basic hydrolysis of polyamides

• amines (NH2)

• carboxylates (salts of carboxylic acid group)

give the basic hydrolysis of this

Polyamide + NaOH →

→ amine + carboxylate (Na+COO-)

polyamide + HCl →

→ carboxylic acid + ammonium salt (NH4Cl)

why are condensation polymers biodegradable

ester bonds and amide bonds are able to be hydrolysed