Polymer Synthesis CHEM 421 Reading (Odian Book): Chapter 1.

Polymer SynthesisCHEM 421

Reading (Odian Book):

Chapter 1

Polymer SynthesisCHEM 421

Polymer Parameters

• Chemical structure– Chemical composition and distribution

– Sequence length and distribution

• Molecular weight and distribution

• Chain isomerism

• Morphology

• Topology

• Additives

• Cost

Polymer SynthesisCHEM 421

Chemical Composition

Polymer SynthesisCHEM 421

Chemical Composition

• Infinite chain model notation

• How best to characterize?

• Why does sequencing matter?

• Synthetic approaches?

• Compositional distribution?

• Branching? (refer to as topology…)

Polymer SynthesisCHEM 421

Polymer Parameters

• Chemical structure– Chemical composition and distribution

– Sequence length and distribution

• Molecular weight and distribution

• Chain isomerism

• Morphology

• Topology

• Additives

• Cost

Polymer SynthesisCHEM 421

Molecular Weight

CH2 CH

i

Pro

per

ty

“X”

Molecular Weight

“X” = tensile strengthdensityTgetc

Polymer SynthesisCHEM 421

Molecular Weight

CH2 CH

i

Mn = Σ ni Mi

Σ ni

Mw = Σ wi Mi

Σ wi

Polymer SynthesisCHEM 421

Molecular Weight

Mn = Σ ni Mi

Σ ni

Mw = Σ wi Mi

Σ wi

• Populations– Memphis, TN 700,000

– Montrose, CO 10,000

– Effingham, IL 12,000

– Freeman, SD 1,500

• What is the Average Population?– 723,500 ÷ 4 = 180,875

– Of these four cities, the average city population is 180,875

• Let’s think about the people…

• What size city does the average person among these populations live in?

– 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

Polymer SynthesisCHEM 421

Molecular Weight

Mn = Σ ni Mi

Σ ni

Mw = Σ wi Mi

Σ wi

• Populations– Memphis, TN700,000

– 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!

Polymer SynthesisCHEM 421

Molecular Weight

• What is the significance of the spread?

• Polydispersity index (PDI)

• PDI of polypeptides and DNA

• How does magnitude of MW relate to synthesis?

• How do you control PDI?

CH2 CH

i

Mn = Σ ni Mi

Σ ni

Mw = Σ wi Mi

Σ wi

Polymer SynthesisCHEM 421

Molecular WeightDistribution

Polymer SynthesisCHEM 421

Gel Permeation Chromatography

• What is principle behind GPC?

• Direct or indirect method?

• Why so useful?

• Drawback?

Det

ecto

r R

esp

on

se

Elution Volume (mL)

Polymer SynthesisCHEM 421

Time of Flight Mass Spectrometry (TOF-SIMS)

Polymer SynthesisCHEM 421

Time of Flight Mass Spectrometry (TOF-SIMS)

Polymer SynthesisCHEM 421

Time of Flight Mass Spectrometry (TOF-SIMS)

Polymer SynthesisCHEM 421

Polymer Parameters

• Chemical structure– Chemical composition and distribution

– Sequence length and distribution

• Molecular weight and distribution

• Chain isomerism

• Topology

• Morphology

• Additives

• Cost

Polymer SynthesisCHEM 421

Chemical Composition Distribution (CCD)

• Interplay between CCD and MWD…

• How to measure?

• Ramifications?– Catalysis?

– Phase separation?

– Optical properties?

– Degradation rates?

– Toxicity?

• Sequence length distribution

Polymer SynthesisCHEM 421

Polymer Parameters

• Chemical structure– Chemical composition and distribution

– Sequence length and distribution

• Molecular weight and distribution

• Chain isomerism

• Morphology

• Topology

• Additives

• Cost

Polymer SynthesisCHEM 421

Chain Isomerism

• Regio-isomers

• Stereo-isomers

• Geometric isomers

• Conformational isomers

Polymer SynthesisCHEM 421

Regio-isomers

CH2 CH

x

CH2 CH

x

CH2 CH

x

... ...

CH2 CH

x

CH CH2 CH2 CH

x

... ...

x

defect

Polymer SynthesisCHEM 421

Regio-isomers

CH2 CH

OH

CH CH2 CH2 CH

OH

... ...

OH

CH2 C

O

C CH2 CH2 CH

OH

... ...

O

H H

Polymer SynthesisCHEM 421

Regio-isomers

H H H H

F F F F

H H H H

F F F F

......

H F H H

F H F F

H F H H

F H F F

......