Polymers

Question 1

What are Polymers?

Answer 1

• Macromolecules formed by polymerisation of smaller molecules

Question 2

What are Polymer’s used in pharmacy as?

Answer 2

• Suspending and emulsifying agents
• Viscosity modifiers
• Gels, adhesives
• Controlled/targeted release formulations
• Tablet coating
• Packaging

Question 3

How can polymers build specific properties?

Answer 3

• pH dependent solubility or viscosity
• Biodegradability
• Attachment of functional groups for targeting
• Networked for forming matrices for drug delivery

Question 4

Discuss the Structure of Polymers

Answer 4

• Linear
• Branched
• Network
• Star

Question 5

How can properties such as viscosity, adsorption be altered? (Polymers)

Answer 5

• Changing mwt
• Changing functional groups

Question 6

Discuss Polymers and their Polydispersity

Answer 6

• Most polymers have a rangle of molecular weights
• Use osmotic pressure or chemical analysis
  
  • Number avg. mwt must determied - Mn

Question 7

Discuss degree of Dispersity (Mw/Mn)

Answer 7

• Value of 1 = all monodispersed
• 1.8 - 2.25 = high polydispersity

Question 8

Discuss Viscosity of Polymer Solutions

Answer 8

• Polymers adopt a random coil structure in solution
• Dimensions depend of flexibility of the polymer chain and polymer-solvent interactions
  
  • Larger in a good solvent
  • Tighter in a poor solvent
• The shape changes continuously
• As the polymers interact with eachother, different viscosities are obtained dependent on the polymer and solution
• Viscosity depends on the polymer mwt, structure, interaction with solvent, extent of ionisation
  
  • Change the size of the random coil and polymer interaction with itself and the solvent

Question 9

What is Viscosity (n)

Answer 9

• Resistance of a material to flow under stress
• Elasticity refers to structure of stickiness
• Units: Nm^-2s; SI Unit: Pas

Question 10

Discuss Polymer Viscosity

Answer 10

• Expressed by the relative viscosity
  
  • Ratio between solution viscosity, n, to the pure solvent viscosity

Question 11

Discuss Viscosity: Concentration Dependence

Answer 11

• Viscosity of a polymer solution increases with increasing concentration
• Viscosity of a colloidal solution increases with increasing concentration

Question 12

Discuss Viscosity: Temperature Dependence

Answer 12

• Viscosity of a liquid decreases with increasing temperature