D6 Basic Polymer Properties 2 Flashcards Preview

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Flashcards in D6 Basic Polymer Properties 2 Deck (25)
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1

Three things water soluble polymers are potentially able to do
What does this make water soluble polymers good for?

Increase viscosity of solvents
Swell/change shape
Adsorb at surfaces
Makes good suspending agents

2

In order to dissolve in water, what must a polymer be?

Sufficiently polar

3

What kind of polymer is capable of forming a thin film and what are the uses of this?

Insoluble polymers
Uses : tablet coating, wound dressing, membranes etc

4

The rate of dissolution of a water soluble polymer is depended on the ______________.

Molecular weight

5

Higher molecular weight = Stronger ________
What does this result in?

Forces holding chains together therefore more energy required to force chains apart

6

Velocity of penetration (S) equation

S=KM^-A
K and A are constants
M = polymer weight

7

What does the velocity of penetration tell us?

The rate at which dissolved, considering the polymer weight

8

How do polymers control drug delivery effectively?

Bulk solvent (water) --> Difffusion layer (as in NaCl solid) --> Gel Layer --> Infiltration layer --> Polymer

9

Rather than dissolving, cross-linked water soluble polymers can become ______?
What happens?

Swollen
Large quantities of water become imbided leading to increased volume

10

The ________ of a polymer impacts viscosity by effecting ____________.

Shape
Flow properties

11

What does better polymer - solvent interactions mean for the shape of the structure ?

A more open, expanded polymer structure

12

What is the results of greater polymer - polymer interactions?

Polymer is likely to coil up

13

What is a theta solvent?

Ideal conditions, all interactions cancel

14

How does charge affect shape?
Describe a charged polymer compared to a neutral polymer.

Affects shape and therefore flow and viscosity
Neutral is contracted, lower viscosity
Charged groups, expanded and higher viscosity

15

What is intrinsic viscosity?

Determined by polymer molecular weight and the type of solvent - extrapolate grapg back to C=0 / y axis

16

How to calculate intrinsic viscosity

[(ns-no)/no] /C
ns = viscosity of polymer solution
no = viscosity of the solvent ONLY

17

What is this equation n = KM^a and what are the components?

How can it be calculated from a graph?

n = intrinsic viscosity
K and a are constants
M = molecular weight

Calculate from a grapph
y = mx +c
ln [n] = ln K + a ln [M]

18

The a constant is a reflection of the _________ of the polymer

Examples

Shape

a = 0 for spheres
a = 0.5-0.8 random coils
a = 1.8 rods

19

What happens to viscosity when polymer concentration increases?

Increases

20

What forms when polymer concentration continues to increase?

Gel precipitate forms - viscous cross linked system

21

Two ways polymer gels can be formed

1 swelling of cross linked solid polymer
2 making dissolved polymer less soluble, (increasing polymer polymer interactions)

22

What is a critical gelation concentration?

System when a gel forms from solution contrains a CGC
Below this concentration a gel will not exist

23

Type 1 and Type 2 gels

1. irreversible covalent systems e.g, contact lenses
2. heat reversible e.g. agar

24

What does solubility parameter tell us?

Essentially a measure of cohesion between molecules

25

Solubility parameter equation

S = [(delta Hv - RT)/V] ^1/2
S = solubility parameters
R gas constant
delta Hv = molar enthalpy of vaporisation
T absolute temperature
V molar volume