Thermal curing mechanisms and cross-linking network structure of a novel silicon-containing arylacetylene resin with 2,7-diethynylnaphthalene unit.

Silicon-containing arylacetylene resin and its composites have attracted great interest as emerging heat-resistant materials, but their curing mechanisms and products are still elusive. In this work, the influences of the terminal and inner acetylenes on the curing mechanisms of silicon-containing arylacetylene resin with 2,7-diethynylnaphthalene were first identified by density functional theory. Two reaction pathways were proposed and their products include polyenes, anthracene dimers, and benzene trimers. To gain a distinct observation of the cross-linking process, molecular dynamics simulations were used to construct a cross-linking polymerization model. The effects of the temperature on the cured structure were investigated by analyzing the characteristics of the cross-linked network. As expected, higher curing temperature will make the larger proportion of polyene chain and aromatic ring in the terminal alkyne-terminal alkyne route, meanwhile, for the inner alkyne-inner alkyne route, the short chains and a small amount of aromatic rings are major productions. Overall, our cross-linking method may provide an unique guidance for studying the cured structure of other thermosetting resins.