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DYS: Pharmaceutics > Basic polymer properties > Flashcards

Basic polymer properties Flashcards

1
Q

Macromolecules

A

Molecules made of a large number of atoms

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2
Q

Polymers

A

Substances of a high molecular weight with repeating monomer units

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3
Q

Pharmaceutical applications of polymers

A 
Drugs
Adhesives 
Hydrogels
Suspending agents
Film coatings
Packaging
Giving sets
Tablet matrices
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4
Q

If the polymer is polydisperse,

A

It contains a range of molecular weights

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5
Q

Gel Electrophoresis

A

Separates polymers using charge + molecular weight

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6
Q

What polymer structure is simeticone

A

Homopolymer

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7
Q

Chemical reactivity of polymer depends on

A

Monomers

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8
Q

Physical properties of polymer depends on

A

Arrangement of monomers

How the polymer chains interact with each other and/or the environment

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9
Q

What polymers do not have an exact molecular weight + why

A

Synthetic + naturally occurring polymers

- because they are polydisperse.

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10
Q

Mn

A

Number average molecular weight

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11
Q

Mw

A

Weight average molecular weight

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12
Q

Degree of polydispersity

A

Mw / Mn

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13
Q

What can water-soluble polymers do

A
  • increase viscosity of solvent
  • swell / change shape
  • adsorb at surfaces
    which makes them useful as suspending agents (carbomer, acacia)
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14
Q

Use for insoluble polymers

A

Form thin films for use in tablet coating, wound dressings, membranes

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15
Q

Rate of dissolution of a water-soluble polymer is dependent on…

A

molecular weight

  • high molecular weight means stronger forces keeping chains together
  • therefore more energy needed to break them
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16
Q

Velocity of penetration

A

(of a solvent into the bulk polymer)

S = kM^-A

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17
Q

What are constants in velocity of penetration

A

k + A

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18
Q

What does M mean in velocity of penetration

A

Polymer molecular weight

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19
Q

What does a negative A mean in velocity of penetration

A

S (velocity of penetration) is inversely proportional to the molecular weight

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20
Q

Pharmaceutical uses of water-soluble polymer

A 
Wound-dressings
Contact lenses
Bulk laxatives
Nappies
Vehicles for drug delivery
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21
Q

Crosslinked water-soluble polymers can be come ____

A

Swollen

- large quantities of water can be retained leading to increase volume

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22
Q

How can polymer gels form

A

Swelling of a highly cross-linked polymer

Making dissolved polymer less soluble

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23
Q

Relation between viscosity and concentraion

A

Viscosity increases with polymer concentration

24
Q

Polymer gels will possess a…

A

critical gelation concentration

  • gel cannot be formed below this polymer conc
  • depends on molecular weight
25
Q

Classification of Gels

A

Type 1 = irreversible systems contact lenses)

Type 2 = heat-reversible (gelatin / agar)

26
Q

A greater solubility parameter…

A

A more polar substance

27
Q

Increasing cross-linking speeds of water-soluble polymer speeds up…

A

Dissolution

28
Q

What solvent has an expanded open structure

A

Good solvent

29
Q

What solvent has ideal conditions

A

Theta solvent

30
Q

Poor Solvent

A

High polymer-polymer interaction = compact cotacted structure

31
Q

Example of a good solvent

A

Water

32
Q

example of a poor solvent

A

THF = tetrahydrofuran

33
Q

How can charge of a polymer affect molecular shape

A 
Neutral = polymer contracted, low viscosity
Ionised = groups repel; expanded structure; increased viscosity
34
Q

What structure would the polymer sodium alginate be in a good solvent

A

Expanded open structure

e.g. water

35
Q

What would the polymer sodium alginate structure be in a poor solvent

A

Contracted, compact structure

36
Q

Solubility parameter

A

s = ( △Hv - RT / V ) ^1/2
Measure of cohesion between like molecules
- Used to predict polymer swelling

37
Q

v in solubility parameter

A

Molar volume

38
Q

T in solubility parameter

A

Absolute temperature

39
Q

R in solubility parameter

A

Gas constant

40
Q

△Hv in solubility parameter

A

molar enthalpy (heat) of vaporisation

41
Q

The greater the solubility parameter…

A

more polar the substance

42
Q

What solvent has the highest solubility parameter

A

Water

43
Q

Polymer at Low concentration

A

Isolated polymer chains

Shape + volume determined by polymer-solvent + intra-polymer interactions

44
Q

Mark Houwick

A

n=KM^a
n = intrinsic viscosity
K + a = constants
M = molecular weight

45
Q

a in the mark houwick equation a reflection of

A

Shape of the polymer

46
Q

Shape of polymer with an a value of 1.8

A

Rod

47
Q

Shape of polymer with an a value of 0.5-0.8

A

Random coils

48
Q

Shape of polymer with an a value of 0

A

Spheres

49
Q

Light scattering techniques

A

measure polymer molecular weight + hydrodynamic radius

50
Q

Viscosity Rheological Flow techniques

A

Examine flow properties + polymer shape

51
Q

Analytical ultracentrifugation

A

Separates polymers according to molecular weight

52
Q

Gel electrophoresis

A

Separates polymers according to charge + molecular weight

53
Q

Nuclear magnetic resonance

A

Conformation in solvent, structure

54
Q

Differential scanning calorimetry

A

Used to examine interactions between polymer chains

55
Q

Gel permeation chromatography

A

Separate polymers according to molecular weight

DYS: Pharmaceutics (4 decks)

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