Synthesis and crosslinking reaction of polyacetylenes substituted with benzoxazine rings: Thermally highly stable benzoxazine resins

Abstract

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 °C under N2 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 °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). © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1884–1893

Benzoxazine Containing Fluorinated Aromatic Ether Nitrile Linkage: Preparation, Curing Kinetics and Dielectric Properties

“…It can be attributed to the fact that with the ring-opening of oxazine rings, the formation of H-bonds between intramolecular and intermolecular chains increased. This trends were well consistent with the published literatures [41,42].…”

“…The characteristic absorption observed at around 3289–3555 cm −1 can be mainly assigned to the intermolecular and intramolecular H-bonds, which were formed between the hydroxyl and nitrogen atoms generated from the ring-opening polymerization of oxazine rings [39,40]. As the references reported that the intramolecular H-bonds could turn into intermolecular H-bonds when the temperature went on which contributed to the increase of surfce free energy of cured matrix [41,42]. It was well known that the formation of hydrogen bonds was sensitive to temperature.…”

“…When the temperature went on (>250 °C), due to the higher temperature the reaction of oxazine rings intensively carried out which leaded to the absorption of oxazine ring rapidly decreased. With the ring-opening of oxazine rings, the formation of H-bonds between intramolecular and intermolecular chains increased [42]. However, the characteristic asorbtion of nitrile group at 2230 cm −1 did not exhibit an obvious decrease at various temperature except for 300 °C.…”

Synthesis and crosslinking reaction of a novel polymer containing benzoxazine and phenyleneethynylene moieties in the main chain

“…Poly( 1 )′ exhibited no clear absorption peaks assignable to the original benzoxazine rings. These IR spectroscopic data of the monomer and the polymers before and after heating confirmed the occurrence of ring‐opening reaction of the benzoxazine moieties upon heating to afford a network polymer …”

“…We have reported various π‐conjugated polymers including substituted polyacetylenes and polyphenyleneethynylenes, some of which adopt regulated higher‐order structures originating from the rigid main chain . We have recently synthesized polyacetylenes substituted with benzoxazine rings to find the high thermal stability presumably due to the synergistic effect of the π‐conjugated backbone and benzoxazine moieties . The combination of π‐conjugation and benzoxazine is a promising candidate of future coming high‐performance thermosetting resins exhibiting excellent heat resistance and thermal conductivity compared with conventional benzoxazine resins.…”