Novel polyacetylenes, poly(1) and poly(2) substituted with benzoxazine rings were synthesized by the polymerization of the corresponding acetylene monomers 1 and 2 using Rh catalysts, [(nbd)RhCl](2), and (nbd)Rh+B-Ph4 (nbd=2,5-norbornadiene). The polymers were heated at 250 degrees C under N-2 to obtain the corresponding polybenzoxazine resins, poly(1)' and poly(2)' possessing polyacetylene main chains via the ring-opening polymerization of the benzoxazine moieties. The polyacetylene backbones were maintained after crosslinking reaction at 250 degrees C, which were confirmed by Raman spectroscopy. The benzoxazine resins were thermally highly stable as evidenced by differential scanning calorimetry and thermogravimetric analysis. The surface of poly(1) film became hydrophilic compared to that of poly(1), while the surfaces of poly(2) and poly(2) films showed almost the same hydrophilicity judging from the water contact angle measurement. Poly(1) and poly(2) exhibited refractive indices smaller than those of poly(1) and poly(2). (C) 2018 Wiley Periodicals, Inc.