Polymers: Solid State, Synthesis & Modification

Question 1

What are the 2 types of solid state a polymer can be in?

Answer 1

Amorphous or crystalline

Question 2

Describe the crystalline solid state

Answer 2

• Highly ordered arrays of molecules
• Anisotropic properties
• Definite melting point

Question 3

Describe the amorphous solid state

Answer 3

• Randomly orientated molecules and atoms
• Isotropic properties
• No definite melting point
• Some properties typical for liquid

Question 4

What is a semi-crystalline polymer?

Answer 4

Crystalline zones in an amorphous polymer

Question 5

What are the 3 physical states of amorphous polymers?

Answer 5

Glassy state (hard)
(Tg)
Rubbery state (soft)
(Tl)
Liquid state

Question 6

What does Tl represent?

Answer 6

Liquid transition point = melting point, but doesn’t technically melt

Question 7

What does Tg represent?

Answer 7

Glass transition temperature

Question 8

Describe a polymer below its Tg

Answer 8

Hard and glasy

Question 9

Describe a polymer above its Tg

Answer 9

Soft and elastic

Question 10

What can alter a polymer’s Tg?

Answer 10

When it is mixed with another substance

e.g. a drug

Question 11

What is addition polymerisation?

Answer 11

Small unsaturated monomers (C=C) join up by the opening of the double bond = a long carbon chain of single C-C bonds

Question 12

What is step growth polymerisation (polycondensation)?

Answer 12

Monomers react to first form dimers –> trimers –> longer oligomers –> long chain polymers
Monomers have 2 functional groups
H2O lost during the reaction

Question 13

What is ring-opening polymerisation (ROP)?

Answer 13

Form of chain-growth polymerisation
The terminal end of the polymer chain acts as a reactive centre where further cyclic molecules can react by opening its ring system to form a longer polymer chain