Web Release Date: January 19,
Poly(ethylene-co-propylene macromonomer)s: Synthesis and Evidence for Starlike Conformations in Dilute Solution
and
Department of Chemistry and Chemical Biology and School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, and Kodak Research Laboratories, Eastman Kodak Company, 1999 Lake Avenue, Rochester, New York 14650
Received October 1, 2007
Revised Manuscript Received November 13, 2007
Abstract:
By use of two sequential coordination-insertion polymerizations, a series of ethylene-co-propylene-based comb polymers was synthesized. First, poly(ethylene-co-propylene) macromonomers featuring one
unsaturated chain end were synthesized using a titanium bis(phenoxyimine) catalyst. The macromonomers were
then homopolymerized using a living nickel 
-diimine catalyst. The molecular weights and corresponding number
of arms for each poly(macromonomer) were determined using size-exclusion chromatography with viscometry
detection and universal calibration. Viscosity-molecular weight conformation plots for the poly(macromonomer)s
revealed compact solution structures. Furthermore, viscometric radii for each poly(macromonomer) (Rv) and
corresponding linear macromonomer (Rv)a were determined and the ratio (Rv)/(Rv)a for each pair was compared
to those of a variety of polyisoprene-based star polymers with similar functionality. The comparison revealed
that despite the obvious comb topology of the poly(macromonomer)s their dilute solution conformations correspond
reasonably well to the bona fide polyisoprene stars.
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