Polymers in solution Flashcards
1
Q
Solubility of polymers
A
- When sufficiently polar so dissolve in water
- Water soluable polymers are able to increase viuscosity of solvents (slows settling)
- Swell and change shape in solution
- Absorb at surfaces - emulsifing agents
2
Q
insoluable polymers
A
- Forms thin films for tablet coatings, wound dressing and membranes
- Dont dissolve but csan absorb water
3
Q
Water-soluable polymers
A
- Slower process of dissolution
- Swollen gel layer appears at the surface of the polymer and outside the diffusion layer
4
Q
Layers of polymers during dissolution
A
- Diffusion layer
- Gel layer
- Infiltration layer
5
Q
Infiltration layer
A
- Solvent starting to infultrate the polymer itself
- This enables larger polymer molecules
6
Q
Gel layer
A
- Higher density solvent molecules are in the gel layer
- Would be very hydrated if in the gel layer which is viscous
7
Q
Diffusion layer
A
- Layer where polymer molecules are lost from and diffuse into the bulk solution
8
Q
Extended release drugs
A
- Core of the polymer contains drug
- When dissolution occours the drug would slowly be able to diffuse out
9
Q
Factors that effect solubility
A
- Partially determines rate of dissolution
- Increase in molecular weight causes a decrease in rate of dissolution
- If it is crystaline or amophous
10
Q
Cellulose
A
- Insoluable in water due to lots of hydrogen bonding (crosslinkage)
- Alternating beta glucose
- Used in packaging for transport (cardboard)
11
Q
Methylcellulose
A
- Thickening or suspending agent
- Etherified as added methyl group linkage with 3 hydroxyl groups
- Tablet binding, coating and disintergrate
12
Q
Hydroxypropal methylcellulose
A
- Has hydroxypropal groups making it very water soluable and is used to make film coating
- Water based and viscous held in place for eye drops
13
Q
Dextran
A
- Branched polymer of alpha-dela glucose (dextrose)
- Anticoagulent and plasma expander
