Surfactants, Polymers, and Chelation (Classes 16-18) Flashcards
What is the difference between cohesion and adhesion?
Cohesion is attraction between like molecules; adhesion is attraction between dissimilar molecules
When water beads up on a waxed car, is that an example of increased cohesion or adhesion?
cohesion
Is surface tension the result of cohesion or adhesion?
cohesion
How do you calculate surface tension?
1/2rhpg
What are the most toxic surfactants?
cationic
What are the safest surfactants?
non-ionic
How does a surfactant affect surface tension?
Lowers it
Are high surface activity compounds better at raising or lowering surface tension?
Lowering
What’s the relationship between solubility and surface activity?
Inversely related (Any factor that tends to decrease solubility of a surfactant will increase surface activity; Increasing hydrocarbon chain will increase surface activity)
What does HLB stand for?
Hydrophilic Lipophilic Balance
What does a higher HLB value mean?
Higher HLB -> more hydrophilic; more dominant polar head
What does a lower HLB value mean?
Lower HLB -> more lipophilic; longer carbon chains
When CMC is reached, what happens?
Micelles form
How does HLB value correlate to CMC?
Higher HLB = Higher CMC
Addition of 1 methylene group to a surfactant chain does what to the CMC?
decreases it 3-fold.
What mixture killed michael jackson?
Propofol and lorazepam
What are some properties of polymers?
crystallinity, solubility, polydispersity, glass transition temperature, chain entanglement
Describe crystallinity
The degree to which polymer strands will align in rigid, uniform lines. Less order = amorphous.
Properties of a polymer depend on what 2 things?
Size and shape
Reactivity of a polymer depends on what 2 things?
Chemistry and assembly of units
What is a substance of high molecular weight consisting of repeating monomers called?
polymer
What repeating unit is used in teflon?
CF2
For a polymer to be perfectly monodisperse, what does the PI need to be?
1
What must the polydispersity index be for a polymer to be considered monodisperse?
between 1 and 1.1
What does polydisperse mean?
multiple chains of varying length
When a polymer is placed in temps below its Tg, what are some characteristics of the polymer?
hard, stiff, glassy
When a polymer is placed in temps above its Tg, what are the characteristics of the polymer?
Weak, flexible, ductile
Do short polymer chains have a higher or lower Tg than cross-linked polymer chains?
lower
In polystyrene vs a milk jug, which polymer would have the lower Tg? Which polymer would have shorter chains?
polystyrene. Polystyrene
What factors decrease dissolution rate of a polymer?
Increased molecular weight, crystallinity, cross-linking
A drug encapsulated in a polymer must diffuse through what extra layer before it reaches the diffusion layer?
gel layer
What type of drug delivery system exploits the properties of osmosis?
Oros
What are 4 types of copolymers?
alternating, random, graft, block
Name 4 uses of polymers in pharmacy.
Drug delivery systems, film coatings, IV Admin sets, Membranes & filters, Thickening agents, Tablet excipients (binders, disintegrants), meshes
If you wanted to make a chewable quality polymer, Tg should be about what?
Body temperature
What are some factors that decrease the dissolution rate of a polymer?
Increased molecular weight, increased crystallinity, increased crosslinking
What are some examples of nanocarriers?
liposomes, nanospheres, nanoparticles, nanofibers, nanotubes, nanosuspensions, nanogels
What are 2 types of adsorption?
physical & chemisorption
According to langmuir’s isotherm, what is formed by molecules that adsorb to a solid surface?
monolayer
Give an example of a therapy that uses adsorption?
activated charcoal
Give an example of a therapeutic chelation agent?
EDTA
Give two examples of chelation agents found naturally?
heme & chlorophyll
Do cyclic structures increase or decrease chelate stability?
increase
Is a high log k value associated with greater or less stability?
greater
What is the chelate effect predominantly the effect of?
entropy
What is denticity?
the number of atoms in a single ligand that bind to a central atom in a coordination complex
What needs to be chelated in Wilson’s disease and what is a chelation agent to do it?
Copper; Penicillamine
Tetracycline is used for Rocky mountain spotted fever. What does Tetracycline chelate within the diet?
Milk, iron, antacids
Why do we not give tetracycline to children less than 8?
It will chelate with the teeth
