Polymer Fundamentals- ALL NOTES

Question 1

What are polymers?

Answer 1

-Specific types of macromolecules that are made up of repeating units called monomers

Question 2

What are the different types of polymer structures ?

Answer 2

-Homopolymer, alternating copolymer, random copolymer, block copolymer, graft copolymer

Question 3

What is a graft copolymer?

Question 4

What influences the properties of polymers ?

Answer 4

-Properties of the monomer itself, arrangement of monomers and polymerisation of monomers and polymerisation number, how the polymer chains interact

Question 5

What is cross linking?

Answer 5

-Bridges between straight chain polymers that changes the properties of the polymer

Question 6

What are the differences between polymers and small molecules?

Answer 6

-Polymers will only exist as solid or liquid, polymers are typically more viscous, dissolution of polymers depends on more factors eg. molecular weight, cross linking, crystalline form, polymers have average molecular weight

Question 7

How do you calculate the average molecular weight (Mn) of polymers?

Answer 7

-(moles x mw) + (moles2 x mw2) …/ sum of moles

Question 8

What is Mn?

Answer 8

-Number average molecular weight is the number of moles we have of Mw 1 and so on divided by total number of moles

Question 9

What is Mw?

Answer 9

-Weight average molecular weight is the weight of all the molecules multiplied by molecular weight then divided by the total weight

Question 10

What is the degree of polydispersity?

Answer 10

-Molecular weight/ molecular number

Question 11

What effect can water soluble polymers have?

Answer 11

-Increase viscosity of solvents, swell/change shape, adsorb at surfaces

Question 12

What are the uses of insoluble molecules?

Answer 12

-Tablet coating, wound dressings

Question 13

What are the layers involved in the dissolution of polymers?

Answer 13

-Infiltration, gel and diffusion

Question 14

What factors impact solubility?

Answer 14

-Polymer molecular weight and polymer crystallinity

Question 15

What are the derivatives of cellulose that have use in pharmaceutics ?

Answer 15

-Cellulose-cardboard packaging
-Methycellulose
-Hydroxypropyl methylcellulose- hympromellose and film coated tablets

Question 16

What are the uses of dextran?

Answer 16

-Active ingredient - artificial tears, emergency blood plasma expander and anticoagulant

Question 17

What happens to a ph-sensitive polymer while unionised?

Answer 17

-Groups repel so expanded structure so increased viscosity

Question 18

What is rheology?

Answer 18

-Study of the deformation and flow of matter

Question 19

What is viscosity?

Answer 19

-The resistance to flow-high viscosity means reduced flow

Question 20

What is shear?

Answer 20

-The relative motion between adjacent layers of a moving fluid

Question 21

What is the symbol for rate of flow ?

Answer 21

-Gamma

Question 22

What is the symbol for viscosity ?

Answer 22

-eta

Question 23

What are newtonian fluids?

Answer 23

-Fluids whose rate of flow is directly proportional to the applied stress

Question 24

What is shear rate (gamma)?

Answer 24

-The velocity gradient over the height in the ‘block’ of fluid

Question 25

What is sheer stress (sigma)?

Answer 25

-The force applied in N over the area of the upper surface of the block

Question 26

What is sheer thinning ?

Answer 26

-Fluids that often decrease in viscosity with increasing shear rate

Question 27

What is shear thickening ?

Answer 27

-Fluids that increase in viscosity with increasing shear rate

Question 28

What happens at a molecular level during shear-thinning?

Answer 28

-high molecular weight molecules become entangled and resist flow, with shear stress eg shaking the bottle, the molecules align with the direction of flow

Question 29

What is plastic or Bingham flow?

Answer 29

-Some fluids only flow after a certain amount of shear stress has been applied

Question 30

What happens to viscosity of molecules at low concentration?

Answer 30

-Isolated polymer chains, shape and volume determined by polymer solvent and interactions

Question 31

What happens to viscosity of molecules at high concentrations ?

Answer 31

-Inter-penetrating chains, polymer movement hindered by neighbouring chains

Question 32

How can viscosity be measured according to BP?

Answer 32

-Capillary viscometer for newtonian and rotating viscometer for newtonian and non-newtonian

Question 33

How does a capillary viscometer work?

Answer 33

-Flow of fluid through a small tube under gravity is measured, apparatus clamped in water bath at desired temperature, suction applied to other tube to pull liquid up then measure time it takes to flow from one mark to the other

Question 34

How does a rotating viscometer work?

Answer 34

-One cylinder with the fluid being investigated inside then solid mass inside, second cylinder is rotated at consistent speed and drag exerted on a body measured

Question 35

What is the primary pack?

Answer 35

-The packaging that is in direct contact with the drug itself

Question 36

What are the features of secondary packs?

Answer 36

-Contain the primary pack and any other components needed, made of paperboard generally, protects against mechanical damage and protect against light

Question 37

What are the features of glass as pharmaceutical packaging?

Answer 37

-Different types available based on properties, can be moulded into different shapes, widely recycled.

Question 38

What are the two main types of glass used in packaging?

Answer 38

-Neutral glass -borosilicate glass -soda-lime-silica glass -silica containing alkali metal oxides

Question 39

What are the types of plastic polymers used in packaging?

Answer 39

-Amorphous and crystalline/ semi-crystalline

Question 40

What are amorphous plastics?

Answer 40

-Eg. PVC, have good transparency, can be made more flexible for infusion bags, some permeability to water and organic vapour

Question 41

What are crystalline polymers?

Answer 41

-Eg. PVDC, tough and stiff, good heat resistance, chemically inert

Question 42

What are commonly used plastics in pharmaceutics?

Answer 42

-PVC, PP (polypropylene), HDPE (high-density polyethylene), polyethylene terephthalate (PET)

Question 43

What are the advantages of using metal in packaging?

Answer 43

-Mechanically strong and shatterproof, able to withstand heat, impermeable to light, liquids and vapours

Question 44

What is an issue with using metal packaging?

Answer 44

-Expensive, heavy and can react with medicine

Question 45

What metals are used in packaging?

Answer 45

-Aluminum, tinplate