Polymers 4: Polyelectrolytes Flashcards Preview

PM2B: Journey Through the GI tract > Polymers 4: Polyelectrolytes > Flashcards

Flashcards in Polymers 4: Polyelectrolytes Deck (23):
1

What are polyelectrolytes?

Polymers have ionisable functional groups (charged groups)

2

What are polybases, polyacids and polyampholytes also known as?

1. Polybases: Cationics polyelectrolytes

2. Polyacids: Anionic polyelectrolytes

3. Polyampholytes: Amphoteric polyelectrolytes

3

What makes a weak anionic polyelectrolytes? And polymers with SO3- groups usually represent what?

1. Weak: Carboxylic acid group attached

2. Represents spermacidal and viracidal properties

4

How do you ionise polyacrylic acid?

Adding a base

5

Give examples of an anionic polyelectrolyte?

1. Poly (acrylic acid)

2. Heparin

6

Give examples of cationic polyelectrolytes?

1. Chitosan (weak)

2. Polyethyleneimine

7

How do you protonate chitosan?

1. Presence of acid causes NH2 group to protonate to NH3

8

Give examples of amphoteric polyelectrolytes?

1. Carboxymethylchitosan

2. Gelatin (derived from collagen)

3. Proteins (BSA)

9

What is the isoelectric point?

1. The pH at which the effective charge of the macromolecule is zero

2. Usually where polymers precipitate

10

How can you tell when a amphoteric polyelectrolyte charge is zero?

When there's a positive and negative charge that cancel each other out

11

What is viscosity?

The measure of a materials resistance to flow as a result of the internal friction of the material's molecule

12

What are the different confrontation of macromolecules in solution?

1. Globule

2. Statistical coil

3. Rigid rod

4. Helix

13

What does confrontation depend on?

1. Chain flexibility

2. Polymer to solvent interactions

14

As the confirmation of polymers go from unfolded chain to aggregates of macromolecules, what happens to the viscosity?

Decreases

15

Describe what Rheology is?

The deformation of structures when pressure is applied to them

16

What is newtons law equation?

1. Shear stress (s-1)

2. Applied stress (N)

3. Dynamic (absolute) viscosity (Nm-2s)

17

How do you work out the relative viscosity of a solution?

t solution/ t solvent

18

How do you work out the specific viscosity?

(n solution - n solvent) / n solvent

19

How do you work out reduced viscosity?

Specific viscosity / C polymer

20

What is the Mark-Kuhn-Houwink equation and define each of the constants?

1. [n] = K x Mv^alpha

2. K and alpha are specific set of constants that are different for every polymer to solvent combination at a given temperature

21

What does it mean in the Mark-Kuhn-Houwink equation when the alpha value is equal to 0.5, between 0.5 and 0.8, and

1. 0.5 is the ideal solvent for a flexible polymer

2. 0.5 to 0.8 is a flexible polymer in good solvent

3. 0.8 or more means stiff chain

22

What is a gel that's made from polysaccharides?

1. Alginate

2. Anionic Polysaccharide that's extracted from brown algae

23

What are the properties of alginates?

1. Made up of soluble potassium and sodium alginates in water

2. Form physical gels in contact with divalent metal ions (calcium, strontium, zinc)