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Abstract
Miniemulsion Polymersation of a Bifunctional Macromonomer
Evaluation of the miniemulsion polymerisation of
a hydrophobic bifunctional macromonomer was undertaken. The rate of polymerisation
of the macromonomer was faster when the reaction was carried out using a
water-soluble initiator, potassium persulphate, KPS, than when an oil-soluble
initiator, 2,2'-azobis(isobutyronitrile), AIBN, was used. Unsaturation peaks
were no longer observable in the 1 H NMR spectrum of the reacted
macromonomer when the gel content was ~50%. In both cases, depending on
the reaction time, crosslinked products were obtained. For the KPS-initiated
homopolymerisation, 50% - 60% gel content was already obtained by the first
hour of reaction, while similar gel development in the macromonomer was
only observed after 6 h - 12 h of polymerisation when AIBN was used. The
polymerised macromonomer (using AIBN as initiator) exhibited a distinct
physical change when water was removed, only when the gel content was ~50%,
which corresponded to a substantial loss of unsaturation peaks in the 1H
NMR spectrum. The gel content remained low (< 10%) earlier in the polymerisation
despite the steady increase in the reaction of the double bonds of the macromonomer.

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