Polymer Synthesis
CHEM 421
Reading (Odian Book):
Chapter 1
Polymer Parameters
• Chemical structure
– Chemical composition and distribution
– Sequence length and distribution
• Molecular weight and distribution
• Chain isomerism
• Morphology
• Topology
• Additives
• Cost
Polymer Synthesis
CHEM 421
Chemical Composition
Polymer Synthesis
CHEM 421
Chemical Composition
Polymer Synthesis
CHEM 421
• Infinite chain model notation
• How best to characterize?
• Why does sequencing matter?
• Synthetic approaches?
• Compositional distribution?
• Branching?
(refer to as topology…)
Polymer Parameters
• Chemical structure
– Chemical composition and distribution
– Sequence length and distribution
• Molecular weight and distribution
• Chain isomerism
• Morphology
• Topology
• Additives
• Cost
Polymer Synthesis
CHEM 421
Molecular Weight
Polymer Synthesis
CHEM 421
CH2
CH
Property “X”
i
Molecular Weight
“X” = tensile strength
density
Tg
etc
Molecular Weight
CH2
CH
i
Mn =
Σ ni Mi
Σ ni
Mw =
Σ wi Mi
Σ wi
Polymer Synthesis
CHEM 421
Molecular Weight
Polymer Synthesis
CHEM 421
• Populations
Mn =
Mw =
– Memphis, TN
700,000
– Montrose, CO
10,000
– Effingham, IL
12,000
– Freeman, SD
1,500
Σ ni Mi
Σ ni
• What is the Average Population?
Σ wi Mi
Σ wi
• Let’s think about the people…
• What size city does the average person among
these populations live in?
– 723,500 ÷ 4 = 180,875
– Of these four cities, the average city population
is 180,875
– The average person does not live in a town of a
population of 180,875…
– Most of the people live in a town with a lot more
than 180,000 people…
– Need a weighted average
Molecular Weight
Polymer Synthesis
CHEM 421
• Populations
Mn =
Mw =
Σ ni Mi
Σ ni
Σ wi Mi
Σ wi
– Memphis, TN
700,000
– Montrose, CO
10,000
– Effingham, IL
12,000
– Freeman, SD
1,500
• Weighted average
– 700,000 ÷ 723,500 = 0.9675
– Take fraction and multiply that by the population of
Memphis 0.9675 x 700,000 = 677,263
– Do the same for the others
» 700,000 x 700,000 / 723,500
= 677,263
»
10,000 x 10,000 / 723,500
=
138
»
12,000 x 12,000 / 723,500
=
199
»
1,500 x 1,500 / 723,500
=
3
677,603
– The average person lives in a city of about 677,600
– More realistic than saying the average person lives in
a city of 180,000!
Molecular Weight
CH2
Polymer Synthesis
CHEM 421
• What is the significance
of the spread?
CH
i
• Polydispersity index (PDI)
• PDI of polypeptides and
DNA
Mn =
Mw =
Σ n i Mi
Σ ni
Σ wi Mi
Σ wi
• How does magnitude of
MW relate to synthesis?
• How do you control PDI?
Molecular Weight
Distribution
Polymer Synthesis
CHEM 421
Gel Permeation
Chromatography
Polymer Synthesis
CHEM 421
• What is principle behind
GPC?
• Direct or indirect method?
Detector Response
• Why so useful?
• Drawback?
Elution Volume (mL)
Time of Flight Mass
Spectrometry (TOF-SIMS)
Polymer Synthesis
CHEM 421
Time of Flight Mass
Spectrometry (TOF-SIMS)
Polymer Synthesis
CHEM 421
Time of Flight Mass
Spectrometry (TOF-SIMS)
Polymer Synthesis
CHEM 421
Polymer Parameters
• Chemical structure
– Chemical composition and distribution
– Sequence length and distribution
• Molecular weight and distribution
• Chain isomerism
• Topology
• Morphology
• Additives
• Cost
Polymer Synthesis
CHEM 421
Chemical Composition
Distribution (CCD)
Polymer Synthesis
CHEM 421
• Interplay between CCD
and MWD…
• How to measure?
• Ramifications?
– Catalysis?
– Phase separation?
– Optical properties?
– Degradation rates?
– Toxicity?
• Sequence length
distribution
Polymer Parameters
• Chemical structure
– Chemical composition and distribution
– Sequence length and distribution
• Molecular weight and distribution
• Chain isomerism
• Morphology
• Topology
• Additives
• Cost
Polymer Synthesis
CHEM 421
Chain Isomerism
• Regio-isomers
• Stereo-isomers
• Geometric isomers
• Conformational
isomers
Polymer Synthesis
CHEM 421
Regio-isomers
...
CH2
CH
CH2
x
...
CH2
CH
CH2
x
CH
CH
x
x
CH2
CH
...
x
CH2
CH
x
defect
...
Polymer Synthesis
CHEM 421
Regio-isomers
...
...
CH2
CH2
CH
CH
OH
OH
C
O
H
H C
O
CH2
CH2
Polymer Synthesis
CHEM 421
CH
...
OH
CH2
CH2
CH
OH
...
Regio-isomers
F F
Polymer Synthesis
CHEM 421
F F
F F
F F
...
...
H H
HH
F F
HH
H H
HH
F F
F F
...
...
HH
F F
HH
HH