10/10-10, 204R

Front 1

Polymer

Back 1

Long Chain of Monomers

Front 2

Homopolymers

Back 2

Polymers made from a singe type of monomer a-a-a-a-a-a-a

Front 3

Copolymers

Back 3

Polymers made from two types of monomers

Front 4

Random copolymer

Back 4

a-a-b-a-b-b-b-b-a-

Front 5

Alternating copolymer

Back 5

a-b-a-b-a

Front 6

Block(diblock) copolymer

Back 6

aaaaaaabbbbbbb

Front 7

Block(triblock) copolymer

Back 7

aaaaaaabbbbbbbaaaaaaaa

Front 8

Graft copolymer

Back 8

Front 9

Linear polymer

Back 9

Front 10

Branched polymer

Back 10

Front 11

Network polymer

Back 11

Front 12

Solubility of Linear polymer?

Back 12

Usually soluble

Front 13

Solubility of branched polymer?

Back 13

Usually soluble

Front 14

Solubility of Network polymer?

Back 14

May swell but will not dissolve

Front 15

Elastomers

Back 15

Front 16

Thermosets

Back 16

Front 17

Thermoplastics

Back 17

Front 18

Back 18

Glass transition temperature

Front 19

Amorphous Thermoplastics

Back 19

Front 20

Semi-crystalline thermoplastics(SCT)

Back 20

Front 21

Molar Mass (M)(polymer context)

+equation

Back 21

mass of 1 mole of polymer chains gmol⁻¹

M = xM₀ or M = nM₀

Front 22

Degree of Polymerisation, (x or n)

Back 22

Number of monomer per polymer chain

Front 23

Back 23

Molar mass of a polymer chain with i repeat units

Front 24

Back 24

Total number of polymer molecules of molar mass Mi

Front 25

Back 25

Front 26

Back 26

Front 27

Back 27

Front 28

Polydispersity index (PDI)

Back 28

Front 29

Back 29

Front 30

What do you understand by molecular weight distribution?

Back 30

Front 31

What do Mn and Mw mean relative to each other?

Back 31

Front 32

What is step growth polymerisation?

Back 32

Front 33

What is chain growth polymerisation?

Back 33

Front 34

What is a Polyester?

Back 34

Polymer with units joined by ester groups, typically formed by the condensation (elimination)reaction between an diacid and a dialcohol or compound with one acid and one alcohol

Front 35

What is a Polycondensation reaction?

Back 35

A Step growth polymeraisation reaction involving the condensation (elimination reaction) between monomers (acid and alcohol)

Front 36

What is polyaddition?

Back 36

Front 37

What is Carothers theory?(full, can ignore)

Back 37

Front 38

What is Carothers theory valid for?

Back 38

Valid for RA₂ + RB₂ polymerisation in which there are equal numbers of A and B functional groups

Front 39

Inplications of Carothers theory?

Back 39

Front 40

Back 40

Number average degree of polymerisation

Front 41

What is the number average degree of polymerisation? (equation)

Back 41

Front 42

What is p?

Back 42

Extent of reaction.

Front 43

What is extent of reaction? (equation)

Back 43

Front 44

What is Carothers Theory?

Back 44

Method of anaylsis for predicting the molar mass of polymers prepared by step growth polymerisation

Front 45

Carothers Equation?

Back 45

Front 46

How is number average molar mass related to degree of polymerisation?

Back 46

Front 47

How do we get the mean molar mass of a monomer unit?

Back 47

Front 48

What is Carothers theory restricted to?

Back 48

Front 49

What allows the prediction of size distributions?

Back 49

Statistical theory(Flory)

Front 50

What is statistical theory?

Back 50

Front 51

What does statistical theory give us?

Back 51

allows us to predict the most probably weight fraction distribution at various extents of reaction p

Front 52

Discuss Chain growth mechanisms?

Back 52

describe polymerisations in which the polymer chain grows only by reaction between monomer and a reactive end group at the growing chain end.

Front 53

Steps of Chain growth?

Back 53

initiation, propagation and termination

Front 54

Types of chain growth mechanisms?

Back 54

Free radical

controlled free radical (ATRP, RAFT, NMP)

Anionic polymerisation

cationic polymerisation

ring opening polymerisation

coordination polymerisation

ring opening metathesis polymerisation

Front 55

Discuss initiation?

Back 55

usually two steps:

i) Formation of free radicals from an initiator by homolytic scission of a single bond (heat or light) or single electron transfer (redox)

ii) addition of initiating radical to monomer

Front 56

What is the general structure of of monomers polymerised by free radical polymerisation?

Back 56

CH₂=CR₁R₂

Front 57

How is homolysis achieved?

Back 57

Homolysis/thermolysis can be achieved with compounds containing peroxide or azo (-N=N-) linkages

Thermolysis occurs at 50-100⁰C,

Photolysis, or single electron transfer is used when low temp required

Front 58

Discuss single electron transfer?

Back 58

Front 59

Which mode of single electron transfer dominates?

Back 59

depends on steric hindrance, and the stability of the resulting radical

Front 60

Propagation?

Back 60

Front 61

Termination?

Back 61

Front 62

discuss chain transfer?

Back 62

Front 63

Discuss transfer constants?

Back 63

transfer constants increase with ease of bond cleavage and stability of radical

Front 64

Discuss autoacceleration?

Back 64

AKA gel effect occurs when conc of monomer is high,

-during reaction viscosity increases

=>reduced mobility of chains

=>termination becomes diffusion controlled - kt decreases

=> propagation unaffected - monomer molecules are mobile

+ polymerisation is exothermic => speeds up reaction

+ viscocity makes dissipation of energy difficult

=> explosion

Front 65

Discuss Living (Anionic) Polymerisation?

Back 65

Well controlled, predictable reproducible, low polydispersity, structural homogeneiety

-no inherant termination reaction

Front 66

Free radical v anionic polymerisation?

Back 66

Front 67

Experimental criteria for living polymerisation?

Back 67

1) constant number of active centres

2) polymerisation proceeds until all monomer has been consumed

3) Mn is a linear function of conversion

4)Mn controlled by the stoichiometry

5) Narrow molecular weight distribution

6) block copolymers by sequential addition of monomers

7) chain-end functionalization by controlled termination is quantitative

Front 68

Why is Mn controlled by the stoichiometry of reaction for living polymerisation?

Back 68

Front 69

Why have living polymerisations got narrow molecular weight distribution?

Back 69

Front 70

Random coils?

Back 70

random coil describes a polymer conformation, where the monomer sub units are arranged randomly (but bonded)

-statistical distribution of shapes for all the polymer chains instead of a single specific shape

-polymer chains are dynamic

-polymer chains in solution or in the amorphous regions of solid state assume (approximate) random coils

Front 71

Rod?

Back 71

as the back bone of a coil becomes stiffer it will be come a rod

Front 72

Contour lengeth?

Back 72

simplest measure of chain dimension

- length of the polymer chain along its back bone

contour length = nL where n = number of bonds and l = length of bond

Front 73

Fully extended end to end distance?

Back 73

nl cos(90-θ/2)

Front 74

Root mean square end-to-end distance?

Back 74

Front 75

Freely jointed chain model

Back 75

Front 76

RMS vs contour length?

Back 76

RMS is a factor of n¹/² smaller

Front 77

RMS radius of gyration?

Back 77

Front 78

Valence angle model?

Back 78

Front 79

Isomeric state theory?

Back 79

Front 80

Chain stiffness/ characteristic ratio?

Back 80

Front 81

Excluded volume?

Back 81

Front 82

Environmental effects upon polymer?

Back 82

Front 83

solvent effects on polymer?

Back 83

In dilute solution there are no polymer-polymer interactions

- in a good solvent, favourable solvent-polymer interactions

=> α > 1 = > polymer expands from unperturbed dimensios

-bad solvent

=> α≤ 1 => polymer collapes often precipitating

Front 84

Theta conditions?

Back 84

When polymer-solvent interactions are suffcient to cancel polymer segment - polymer segment interactions

α = 1

solvent is called a theta solvent

solvents can be good, bad or theta depending on temp

Front 85

T>Tg

Back 85

-polymer behaves as a viscous liquid

-individual chains posses enough thermal energy to flow past each other

-polymer has a high degree of free volume

Front 86

T<Tg

Back 86

-Individual chains no longer able to flow

-polymer has much reduced free volume => no space to move

-polymer becomes stiff and glassy

Front 87

what physical properties change when a polymer passes through Tg

Back 87

Mechanical properties (solid to liquid)

refractive index

heat capacity

thermal expansion

Front 88

First order and second order transitions?

Back 88

First order transition - change in a fundamental thermodynamic property (like H or V)

second order transition - change in a first derivative e.g. Cp =(dH/dT), α = 1/V (dV/dT)

α = volume thermal expansion coefficient

Front 89

Specific Volume and free volume around Tg

Back 89

`

Front 90

fractional free volume?

Back 90

Front 91

Dependence of Tg upon chemical structure?

Back 91

1) flexible backbones give low Tg (unhindered rotation)

2) polymers with bulk side groups inclease Tg by restricting bond rotation => stiff chain

3) polymers with flexible side groups decrease Tg by increasing free volume

4) polymers with polar side groups increase Tg due to increased interactions

5) block and graft copolymers have multiple distinct values of Tg, while random / altenating have one Tg

Front 92

Dependence of Tg upon molar mass?

Back 92

Front 93

methods of measuring Tg?

Back 93

Refractive index vs T,

Specific Volume vs T,

Heat capacity ( DSC),

mechanical properties DMA

Front 94

Differential scanning calorimetry?

Back 94

Two heaters heat two pans at the same heating rate, sample pan has to work harder, DSC measures how much more heat is required plot difference v Temp,

Front 95

Dynamic mechanical analysis?

Back 95

mearuser variation in mechanical properties as a function of force, strain, frequency, time and temperature

(applying a constant fonce and varying T allows Tg to be measured

(more sensitive than DSC)

Front 96

Discuss Thermoplastic elastomers?

Back 96

at room temp: -elastomeric rubbery networks

- can be stretched,

-recover

-posses crosslinks

at elevated temp:- thermoplastics

-tehy can be heated and processed

-cooled and then reheated

Front 97

explain thermoplastic elastomers?

Back 97

crosslinks are not permanent covalent bonds but reversible physical crosslinks

Front 98

Phase separation of polymers?

Back 98

polymer blends -macrophase separation upon cooling from melt

block copolymers - microphase separation on cooling

Front 99

methods of multiblock synthesis?

Back 99

coupling

sequential addition of monomers

sequential additino of monomers difunctional initiator