Polymers Flashcards
1
Q
What are Polymers?
A
- Macromolecules formed by polymerisation of smaller molecules
2
Q
What are Polymer’s used in pharmacy as?
A
- Suspending and emulsifying agents
- Viscosity modifiers
- Gels, adhesives
- Controlled/targeted release formulations
- Tablet coating
- Packaging
3
Q
How can polymers build specific properties?
A
- pH dependent solubility or viscosity
- Biodegradability
- Attachment of functional groups for targeting
- Networked for forming matrices for drug delivery
4
Q
Discuss the Structure of Polymers
A
- Linear
- Branched
- Network
- Star
5
Q
How can properties such as viscosity, adsorption be altered? (Polymers)
A
- Changing mwt
- Changing functional groups
6
Q
Discuss Polymers and their Polydispersity
A
- Most polymers have a rangle of molecular weights
- Use osmotic pressure or chemical analysis
- Number avg. mwt must determied - Mn
7
Q
Discuss degree of Dispersity (Mw/Mn)
A
- Value of 1 = all monodispersed
- 1.8 - 2.25 = high polydispersity
8
Q
Discuss Viscosity of Polymer Solutions
A
- 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
9
Q
What is Viscosity (n)
A
- Resistance of a material to flow under stress
- Elasticity refers to structure of stickiness
- Units: Nm-2s; SI Unit: Pas
10
Q
Discuss Polymer Viscosity
A
- Expressed by the relative viscosity
- Ratio between solution viscosity, n, to the pure solvent viscosity
11
Q
Discuss Viscosity: Concentration Dependence
A
- Viscosity of a polymer solution increases with increasing concentration
- Viscosity of a colloidal solution increases with increasing concentration
12
Q
Discuss Viscosity: Temperature Dependence
A
- Viscosity of a liquid decreases with increasing temperature
