Chapter 2c

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Polymerization Techniques

• Bulk-no solvent just monomer + catalysts

• Solution Polymerization-in solvent

• Suspension-micron-millimeter spheres

• Emulsion-ultrasmall spheres

Bulk Polymerizations

RareOverheat & explode with scale upNo solvent-just monomerPolymer usually vitrifies before doneBroad MW distribution

Acrylic sheets by Bulk polymerization of MMA

Storage of vinyl monomers in air = peroxide initiated polymerizations

Tankcar of styrene2005 in Ohio

Solution Polymerization • Better control of reaction temperature• Better control of polymerization• Slower• Not very green-residual solvent

Suspension Polymerization

• Oil droplets dispersed in water

• Initiator soluble in oil

• Greener than solution polymerization

Filter off particles of polymer

Emulsion Polymerization

Still oil in water (or the reverse)Initiator in waterSmaller particles (latex)Excellent control of tempSolution turns white

Polystyrene latex

Suspension Emulsion Mini-emulsion Micro-emulsion

Monomer in oil Monomer in oil Monomer in oil Monomer in oil

Initiator in oil Initiator in water Initiator in waterInitiator in water

Less Common Polymerization Techniques

• Solid state polymerization– Polymerization of crystalline monomers

• Diacetylene crystals

• Gas Phase polymerization– Parylene polymerizations

• Plasma polymerization– Put anything in a plasma

Solid State Polymerizations

Heating Oligomeric Condensation Polymers

Tg < X < Tm

Nylons, Polyesters

O

O

O

O

O

HO O

O

O

n

O

O

O

O

O

O O

O

On

OH

250 °C

HOOH

Nylon 66 Tg = 70 °C and Tm = 264 °C

Tg = 67 °C and Tm = 265 °C

Solid State Polymerizations

Topological Polymerizations: Polymerization of crystals

Quinodimethane polymerizations

Di- and Triacetylene polymerizationsIn single crystals

Solid State Polymerizations of Fullerenes

Topological polymerization in 3-D

Gas Phase Polymerization

1) Light olefins2) Parylenes

LIGHT OLEFINS

Ethylene and propylene

2004 Global PE Demand: 136 Billion Pounds

• Food Packaging• Hygiene & Medical• Consumer & Ind. Liners• Stretch Films• Agricultural Films• HDSS

Film

SOURCE: Nexant/ChemSystems 2005, PTAI 1/05

Types of Polyethylene

O

OOO

O O

OO

O

O

C-OH

O

HDPE (0.940-0.965)“High Density”

LLDPE (0.860-0.926)“Linear Low Density”

LDPE (0.915-0.930)“Low Density”

High Pressure Copolymers(AA, VA, MA, EA)

Gas Phase Polymerization: Light olefins

Oxygen initiator2-3K atmospheres250 °C

Gas Phase Polymerization: Light olefins

Fluidized bed polymerization

MORE FLEXIBLE

Gas Phase Polymerization: Paralene

Gas phasePolymerizes on contactConformal coatingsPinhole freePreserving artifacts (paper)MicroelectronicsMedical devices

Plasma Polymerization

•500 Å - 1 micron thick films•Continuous coatings•Solvent free•High cohesion to surface•Highly cross-linked•Generally amorphous

Plasma Polymerization

Monomers: HydrocarbonsDouble or triple bonds nice, not necessaryFluorocarbonTetraalkoxysilanes (for silica)

P- pumps; PS-power supply; S-substrate

M-feed gas inlet; G-vacuum gauge

Fig1. Bell-jar type reactors Fig 2. Tubular-type reactors

Plasma Polymerization

Plasma Polymerization

PET [Poly(Ethylene Terephthalate)]Multi-layer bottlesNo loss of fizz

Characterization of Polymers

• 1H & 13C Nuclear Magnetic Resonance spectroscopy (NMR)

• Infrared spectroscopy (Fourier Transform IR)

• Elemental or combustion analyses

• Molecular weight

13C NMR is a very powerful way to determine the microstructure of a polymer.

13C NMR shift is sensitive to the two stereocenters on either side on sptectrometers > 300 MHz. This is called pentad resolution.

r mm rmr

mmrm pentad

m = meso (same orientation)r = racemic (opposite orientation)

12 1 2

13C NMR spectrum of CH3 region of atactic polypropylene

Infrared Spectroscopy: Bond vibrations

2-16 Micron wavelength range

polystyreneC=C-H

C-H

C=Cstretch

Infrared Spectroscopy: Bond vibrations

Poly(methyl methacrylate)

C=O

C-O

C-Hstretch

C-H bend

Types of Addition Polymerizations

Ph

Anionic

C3H7 Li C4H9

Ph

Li+ Phn

C4H9

Ph Ph

Li+

n

Ph

Radical

PhCO2•Ph

n

Ph

Cationic

Cl3Al OH2H

PhHOAlCl3

Phn

H

Ph Phn

HOAlCl3

PhCO2

PhPhCO2

Ph Phn

Chemical Modification of Polymers

1) Hydrolysis

2) Oxidation

3) Photochemistry (can be oxidation or not)

4) Chemical crosslinking

5) Chemical modification

O

OCH3

n NaOH

H2O OHn

O

O

H3Cn

Na+

Polyvinylacetate polyvinyl alcohol

On

H

Poly ethylene oxidehv, O2

or ascorbic acid

Me

O

H

SiSi

SiSi

SiR R

R R

R R

R R

R R

Polysilane

hν: UV

O2

SiOSi O

SiO

SiO

R RR

R

RR

R

R

H

polybutadiene

S8

Δ SS

S

See next slide

Chemical Modification of Polyvinyl Alcohol to make Polyvinyl butyral for safety glass

polyvinyl alcohol

OH OH OH OH OH

CH3CH2CH2CHO

O O OH O O

poly vinyl butyral

No PVB

With PVB

Bullet Proof Glass

glass, laminates and polycarbonate sheets are interlaid in a clean room to ensure clarity. In our large autoclave, superheated steam seals the layers together.

Making bullet proof glass

Polycarbonate is Strong Material

Young's modulus (E) 2-2.4 Gpa

Tensile strength (σt) 55-75 Mpa

Exploding CD’s

Mythbusters:> 23,000 rpm CD will shatterScratches or defects are the culprit

52X drive -MAX: 27,500 rpm typical: 11,000 rpm

10,000 RPM = 65 m/s = 145 mph7200 gravities of accelerationAnd approx. 5 MPa stressYield Strength 60 MPa

Nalgene

Polycarbonate Properties

Density: 1.2 g/cc

Young's modulus (E) 2-2.4 Gpa

Tensile strength (σt) 55-75 Mpa

Elongation (ε) @ break 80-150%

Glass transition (Tg) 150 °C

Melting (Tm) 267 °C

Upper working temperature 115-130 °C

$7.3-11/kg

Bisphenol and Endocrine System

100-250 g bisphenol per Liter water in water bottles20 g/Liter per day can disrupt mouse development

vom Saal, F.S., Richter, C.A., Ruhlen, R.R. Nagel, S.C. and Welshons, W.V. Disruption of laboratory experiments due to leaching of bisphenol a from polycarbonate cages and bottles and uncontrolled variability in components of animal feed. Proceedings from the International Workshop on Development of Science-Based Guidelines for Laboratory Animal Care, National Academies Press, Washington DC, 65-69, 2004.

Immune systemAntioxidant enzymesDecreases plasma testosteroneLearning disabilities

vom Saal, F.S., Nagel, S.C., Timms, B.G. and Welshons, W.V. Implications for human health of the extensive bisphenol A literature showing adverse effects at low doses: A response to attempts to mislead the public. Toxicology, 212:244-252, 2005.

Nalgene Substitutes-food and water

• Glass (blender, pitchers, glasses)

• Metal (water bottles)

• Polyethylene (water bottles)

• Polyamide or Nylon (baby bottles)