Step growth polymerisation

Question 1

the prime difference that distinguishes step growth and chain growth polymerisation

Answer 1

reaction mechanism

Question 2

during which stage are monomers gone

Answer 2

dimer, trimer

Question 3

define conversion rate (p)

Answer 3

how many monomers have reacted to form polymers

Question 4

draw the draw of Mn against conversion rate

q: how is Mn at 50% conversion rate?

Answer 4

very low Molecular weight

Question 5

what are the three types of step growth polymerisation?

Answer 5

Poly-condensation

Poly-addition

Addition Condensation

Question 6

which type of step growth polymerisation yields a small molecule

Answer 6

Poly-condensation
Addition Condensation

Question 7

monomer type for step growth polym.

Answer 7

bifunctional
A-R-B or A-R’-A + B-R”-B
where A can react with B but not another A

A-R-B + A-R-B → A-[- R—BA—R-]-B
A-R’-A + B-R”-B → A-[-R’—AB—R”-]-B

Question 8

3 examples under polycondensation

Answer 8

1. polyester
2. polycarbonate
3. Polyamide

Question 9

what are the two ways to make a polyester?

Answer 9

Reaction of hydroxyl (-OH) and carboxylic (-COOH) group

Reaction of hydroxyl (-OH) and ester (-COOR’) groups

Question 10

write down a general equation for hydroxy and carboxylic group using the two types of bifunctional monomers

Q: what type of reaction is taking place for A-R-B

Answer 10

self-condensation ( A reaction where identical molecules (monomers) combine to form larger molecules (oligomers or polymers), releasing a small molecule like water or methanol as a byproduct.)

Question 11

write down a general equation for hydroxy and ester group

Q: what type of reaction is taking place

Answer 11

transesterification(chemical reaction where an ester reacts with an alcohol, acid, or another ester, resulting in the exchange of the alkoxy group)

Question 12

an example equation for the formation of polycarbonate

Q: functional group of carbonate and ester

Answer 12

carbonate: -O-CO-O-
ester: -CO-O-

Question 13

two ways to make a polyamide

Q: is self condensation possible here

Answer 13

1. amino (-NH2) and diacid chloride groups
2. amino and carboxylic group

YES

Question 14

two important examples of polyamide

Answer 14

Nylon 6-6
Kevlar

Question 15

Nylon 6-6

1. what are the two monomers?
2. condition
3. melting temp

Kevlar
1. condition
2. intermolecular force

Answer 15

1. adipic acid and 1,6-hexanediamine
2. interfacial polycondensation
3. 200-280C
4. interfacial polycondensation
5. hydrogen bonds between the chains

Question 16

how to achieve high molecular weight in polycondensation?

Answer 16

1. monomers must be of high purity
2. functionality >= 2 for each monomer unit
3. the two mutually reactive functional groups are in exactly equal molar quantity(stoichiometric balance).
   If one of the group is in excess that group will remain unreacted at the chain ends resulting low molecular weight polymers( only oligomers present)

two means to achieve stoichiometric balance: high purity of monomers and equimolar monomer ratio

Question 17

explain nd derive the carother’s equation

Question 18

Mn Mw and PI based on carothers eqn