Macromer Stabilised Polystyrene Latexes Paul M. Zelisko CHEM 765.
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Transcript of Macromer Stabilised Polystyrene Latexes Paul M. Zelisko CHEM 765.
Macromer Stabilised Macromer Stabilised Polystyrene LatexesPolystyrene Latexes
Paul M. ZeliskoPaul M. Zelisko
CHEM 765CHEM 765
Dispersion PolymerisationDispersion Polymerisation
• can be used to produce narrow dispersed polymer microparticles
• latexes used in paints, liquid chromatography, adhesives
monomerinitiator
stabiliser
H2O/ROH
polymer
Macromolecules. 1997, 30, 5673-5682Colloid Polym Sci. 1997, 275, 716-729J Polym Sci: Part A: Polym Chem. 1993, 31, 2473 - 2479
Stabilising ColloidsStabilising Colloids• electrostatic stabilisation
• steric stabilisation– adsorption– grafting
• macromers– polymers with a functionalised terminus for
physical adsorption at the interface or for grafting to the polymer colloid
O
O
O
n
n
• used to stabilise dispersion polymersiation of styrene in CO2
• no chain transfer to silicone, even under radical conditions
Macromolecules. 1997, 30, 5673-5682J Colloid Interface Sci. 1990, 137, 120
POLY(STYRENE-POLY(STYRENE-bb--DIMETHYLSILOXANE)DIMETHYLSILOXANE)
SiO
Sin
m
Advantages• lowered cost• straightforward
anionic synthesis– narrow molecular
weight distributions
• soluble in many organic solvents
Disadvantage• stabilisation by
adsorption to polymer
POLY(STYRENE-POLY(STYRENE-bb--DIMETHYLSILOXANE)DIMETHYLSILOXANE)
• used in radical dispersion polymerisation of styrene
• can get grafting through terminal group– chemical bond between stabiliser and polymer
METHYLMETHACRYLATE-METHYLMETHACRYLATE-POLY(ETHYLENE OXIDE)POLY(ETHYLENE OXIDE)
OO
O
O
n
• need PEO chains on macromer that are at least 2000 MW to inhibit flocculation
• synthesis of macromer becomes inefficient as PEO reaches limits of effective stability
METHYLMETHACRYLATE-METHYLMETHACRYLATE-POLY(ETHYLENE OXIDE)POLY(ETHYLENE OXIDE)
Colloids and Surfaces, 1986, 17, 1-11
OOHn
toluene
reflux, -H2OOH
SH
O
+ OO
SH
O
n
Colloid Polym Sci, 1997, 275, 716-729
THIOL-ENDED THIOL-ENDED POLY(ETHYLENE OXIDE)POLY(ETHYLENE OXIDE)
• styrene added to stabiliser under radical polymerisation conditions
• maximum 15% of stabiliser grafted to colloid– remainder in aqeuous phase
THIOL-ENDED THIOL-ENDED POLY(ETHYLENE OXIDE)POLY(ETHYLENE OXIDE)
H
C
H.
SR
.SR
C
POLY(ETHYLENE POLY(ETHYLENE GLYCOL)-ISOCYANATEGLYCOL)-ISOCYANATE
OOHn
+N
CO
polyethylene glycolmethyl ether
3-iso-proponyl--dimethylbenzylisocyanate
toluene, 70oCtin(II) dioctoate catalyst
OO N
H
O
n
Macromolecules, 2000, 33, 6664-6671
• can be used in radical and ionic polymerisations
• 1H-NMR showed that 100% of macromer grafts to the polystyrene
• bulky urethane group– hydrolytic stability
• monitor reaction using FT-IR
POLY(ETHYLENE POLY(ETHYLENE GLYCOL)-ISOCYANATEGLYCOL)-ISOCYANATE
~7 nm
POLY(ETHYLENE POLY(ETHYLENE GLYCOL)-ISOCYANATEGLYCOL)-ISOCYANATE
Polystyrene
Stabiliser “shell”
ConclusionsConclusions• develop a macromer to suit
experimental goals
• ideal macromer can react in ionic and/or radical polymerisation
• macromers are an effective means of stabilising colloids