Palladium-Mediated Soluble Precursor Route into Poly(arylethynylenes) and Poly(arylethylenes)

Soluble precursor polymers 8 and 14 were successfully synthesized via the palladium-mediated condensation of 4,4‘-(1,3,2-dioxaborolan-2-yl)biphenyl ( 7 ) with the bis( p -bromophenyl)norbornadiene monomer 5 and the bis( p -bromophenyl)norbornene monomer 13, respectively. The number-averaged molecular weights of these materials were determined by GPC−LS to be 34 000 for 8 and 75 000 for 14 . Thermolysis of 8 by a retro-Diels−Alder reaction began at 260 °C and appeared (by GC−MS analysis of the volatile byproducts) to yield a conjugated polymer with both alkyne and cyclopentadiene functionalities in the polymer backbone; however, TGA analysis indicated that the transformation was accompanied by some decomposition. The analogous thermolysis of 14 to yield the polymer with a double bond in the backbone began at 230 °C and appeared to proceed without the concomitant decomposition.