POLY(ETHYLENE OXIDE) MACROMONOMERS .4. SYNTHESIS AND POLYMERIZATION OF MACROMONOMERS CARRYING STYRYL END GROUPS WITH ENHANCED HYDROPHOBICITY

Poly(ethylene oxide) (PEO) macromonomers with hydrophobically enhanced styryl end groups were prepared by three methods. The first consists of polymerization of ethylene oxide (EO) with potassium alkoxide of mono(t-butyldimethylsilyl)ether of 1,10-decanediol, termination with methyl iodide, desilylation with tetra-n-butylammonium fluoride, followed by coupling with p-vinylbenzyl chloride to afford a p-vinylbenzyloxydecyloxy-ended macromonomer. The second is a simpler method, consisting of polymerization of EO with a simpler potassium alkoxide and termination with p-styrylalkyl bromide to afford a p-styrylalkyloxy-ended macromonomer, but the termination was accompanied with a rather abundant side reaction due to E2 elimination to yield p-styrylalkene and hydroxy-ended PEO. This shortcoming could be overcome by the third method of transforming the hydroxy end group by reacting with about five-fold molar excess of sodium hydride and p-styrylalkyl bromide, except for p-styrylethyl bromide which exclusively reacted by E2 elimination to give p-divinylbenzene. The radical homopolymerizations of the macromonomers obtained were found to be very rapid in water, particularly for those with more hydrophobic styryl end groups, supporting our previous idea of the organized micellar polymerization mechanism for these amphiphilic PEO macromonomers.