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Published August 10, 2014 | public
Journal Article

Synthesis of cyclo-polyolefins


The linear trans-polypentenamer has unique relevance among the synthetic rubbers since it has similar phys. properties to the natural rubber. One of the most exciting new possibilities is the capability of prepg. cyclic polypentenamers. This new type of polymer is of significant theor. and com. interest. Since many of the properties of polymers are controlled by end group and the defects they introduce, cyclic polymers that contain no end groups should show new and valuable phys. properties. Cyclic polymers can result in unique properties in comparison of linear analogs such as different hydrodynamic radii, functional group d. and lower viscosity. Although in the past couple of decades a no. of new cyclopolymer synthetic techniques have been developed, cyclopolypentenamers have not been synthesized and studied. New approaches to the synthesis of such materials have been recently developed. Highly pure cyclopolypentenamer (MW: 36 kDa; PDI: 1.3) have been synthesized in equil. ring opening metathesis polymn. by silica supported Hoveyda-Grubbs second-generation catalyst systems. The polymer yields are comparable with those of linear analogs synthesized by homogeneous ruthenium and tungsten catalyst systems. The Mark-Houwink "a" parameters show significant difference between the linear (0.59 ± 0.4) and cyclic (0.92 ± 0.05) polypentenamers indicating the formation of high no. of double bond contg., rigid cyclic polyolefins. Similar expts. with cyclooctene resulted in the formation of high mol. wt. (939 kDa, PDI: 1.6) and highly pure cyclopolyoctenamer. The silica supported catalysts systems could be recycled three times without significant redn. of polymn. yield. The formed cyclopolymers can be hydrogenated off by Pd/C resulting in cyclopolyethylene at atm. hydrogen pressure and room temp. The synthetic methodol. and anal. of cyclic polyolefins are reported. Synthesis of linear and cyclic polypentenamers. Toluene soln.; room temp.; [cyclopentene] = 2.17 M; 0.01% Ru catalyst loading.

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© 2014 American Chemical Society.

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August 20, 2023
October 20, 2023