Hyperbranched poly(silylenephenylenes) from polycyclotrimerization of A2-type diyne monomers:: Synthesis, characterization, structural modeling, thermal stability, and fluorescent Patterning

A group of hyperbranched poly(silylenephenylenes) (hb-PSPs) were synthesized in high yields (up to 100%) by TaBr5-catalyzed polycyclotrimerization of A(2)-type monomers of silylenediynes [HC C-C6H4- Si(C(n)H2(n+1))(2)-C6H4-C CH, n = 2, 4, 6]. The hb-PSPs are completely soluble in common organic solvents such as chloroform, toluene, and THE Spectroscopic and modeling studies confirmed that the polymers had formed via a [2 + 2 + 2] cyclotrimerization mechanism. Analysis of the triple-bond conversion processes led to the establishment of a relationship between the degree of branching and the fraction of dendritic unit. Computational simulation shed light on the real topological structures of the hb-PSPs. The polymers lost little weights when heated up to 480 degrees C and carbonize in high yields (up to 71 %) after pyrolysis at 800 degrees C. The hb-PSPs possess a unique sigma-pi conjugated electronic structure and emit strong violet-blue light upon photoexcitation. The triple bonds on the peripheries allowed the thin films of the polymers to be readily photo-cross-linked, generating fluorescent photoimages in high resolutions.