Monday, August 20, 2012

Cyclopolymerization To Synthesize Conjugated Polymers Containing Meldrum's Acid as a Precursor for Ketene Functionality

Jeongeun Kim, Eun-Hye Kang, and Tae-Lim Cho

A 1,6-heptadiyne monomer containing a Meldrum acid (ketene precursor) functional group was copolymerized with monomers 1 or 2 (see figure)  to afford solubility using cyclopolymerization with the third generation Grubbs catalyst. Studies from AFM, NMR, and DLS suggested these polymers self-assembled into core-shell type nanoparticles with the insoluble Meldrum's acid facing toward the center. Upon heating to 200 C, Meldrum's acid releases CO2 and acetone and generates a ketene. The formation of ketene was tested through thermal gravimetric analysis, in which a drop in the weight was observed; and infrared spectroscopy. Also upon heating to 240 C for ten minutes, IR signal suggested the ketenes started to react through [2+2] cycloaddition to give cyclobutanedione, which permanently crosslinked the cores.

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