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