Polymers 4 Flashcards
what is a cationic polyelectrolyte
a polymer with positive charged groups (polybases)
what is anionic polyelectrolyte
polymer with negative charged functional groups
what is amphoteric polyelectrolyte
polymer with mixture of charged functional groups
what is an example of polyampholytes
gelatin
proteins (BSA)
what is the isoelectric point
IEP is the pH at which the effective net charge on a macromolecule is 0
at what point do proteins precipitate at
proteins as typical polamphoyltes often precipitate at the isoelectric point thus we can see at what point the IEP is on a protein if we plot its pH and its turbidity
if a polyampholyte is below its IEP
it is positively charged
if a polyampholyte is above the IEP
it is negatively charged
what is viscosity
measure of a materials resistance to flow
it is a result of the internal friction of the materials molecules
what are the 4 conformation of macromolecules in solution
globule
statistical coil
rigid rod
helix
what does the conformation depend on
chain flexibility and polymer solvent interactions
in what form can viscosity not be measured
if a polymer precipitates from solution its viscosity cannot be measured
what is rheology
rheology is the study of the flow and deformation of properties of matter
what is shear rate
shear rate is the rate at which a progressive shearing deformation is applied to some material.
what is shear rate proportional to
shear stress
what is shear rate = to
applied stress divided by dynamic viscosity
what are 3 non newtonian fluids
dilatant flow (tapers off at the end)
simple pseudoplastic flow (slow to start then goes straight)
Simple plastic flow (slow to start and finishes shorter than simple psuedoplastic flow)
what is plastic flow associated with
presence of flocculated particles in concentrated suspension
what is a flocculated particle
Flocculation is a two-step particle aggregation process in which a large number of small particles form a small number large flocs.
when is psuedoplastic flow exhibited in polymers
typically exhibited by polymers in relatively concentrated solution
when is dilitant flow exhibited
certain suspension with a high percentage of dispersed solids.
what are some factors that effect viscosity of poylmer solutions
concentration of polymer in solution molecular weight of a polymer polymer solvent interactions temperature charge of macromolecules solution pH for weak polyelectrolytes presence of small molecules in solution
how does pH affect polyanion viscosity
reduced viscosity as PH increase
how pH affect polycation viscosity
as pH increases more viscous
how ph affect polyampholyte viscosity
viscous at IEP
what are some properties of alginates
sodium and potassium alginates are soluble in water
spotaneously form physical gels upon contact with divalent metal ions
egg box structure between four g residues
how does gaviscon work
works by forming a gel raft (thick layer) on top of the stomach contents soon after it has made contact with the stomach acid
raft acts as a strong physical barrier and helps keep all the components of the stpmach contents in the stomach where they work
not letting them seep back up into the oesophagus where they hurt
what active ingredients does gaviscon advance contain
sodium alginate
sodium bicabonate
calcium carbonate
