A conjugated alkyne functional bicyclic polybenzoxazine with superior heat resistance

Abstract

A difunctional benzoxazine (coPh-apa) with a conjugated alkyne group is synthesized by the oxidative coupling reaction from a monocycle-benzoxazine (Ph-apa) containing an alkyne group. A model compound, 1,4-diphenylbutadiyne (coPa), is used to study the curing reaction process of coPh-apa by DSC, Fourier transform infrared spectroscopy, and 13 C NMR, and the results suggest that the conjugated alkyne groups are involved in the crosslinking reaction via the trimerization reaction of the conjugated alkynyl groups and the Diels-Alder reaction. Furthermore, thermal properties of the polybenzoxazine are studied by dynamic thermomechanical analysis and thermogravimetric analysis. A glass-transition temperature (T g s) of as high as 412 C and a char yield of 75.6% at 800 C under nitrogen are obtained with the aid of the conjugated alkyne groups. Its excellent heat resistance dominates most thermosetting resins and will serve for heat shields.

Toward Taming the Chemical Reversibility of Perfluoropyridine through Molecular Design with Applications to Pre- and Postmodifiable Polymer Architectures

“…The highest observed char yield at 900 °C belonged to poly1g which gave a value of 67%; this high thermal stability was attributed to the ability of the reactive alkynes to undergo a variety of curing reactions that result in crosslinks between the polymer strands with the curing mechanisms most likely being a combination of cyclotrimerization reactions, radical crosslinking reactions, and cycloaddition reactions. 25 Beyond improving the thermal stability of these systems, modification of poly1 led to improved glass-transition temperature (T g ) behavior. Thermal analysis of poly1 demonstrated that it was elastomeric with a T g well below 10 °C.…”

“…Just as was the case in poly1g, poly3c displayed gave the highest char yield of 60% compared with polymers poly3a−poly3f, which was attributed to the same mixture of competitive thermal curing processes. 25 Copolymerizations with Norbornene. Expanding upon the pre-and postfunctionalization of these polymer systems, monomers 1 and 3 were copolymerized with norbornene in THF to yield high-molecular-weight solution-processable polymers poly(1-co-NB) and poly(3-co-NB), respectively (Scheme 5).…”

Hybrids from silazane and allyl‐containing benzoxazine for low‐curing temperature and high‐flame retardance

“…The char yield of PBS increases (from 25.57% to 66.11%) with the gains of weight percent of silazane, but it is barely growing when the weight percent of silazane is more prominent than 80%. The char yield of PBS is nearly as high as acetylene‐functional benzoxazine 38–40 . All of the above results reveal that the cured PBS resin has excellent thermal stability.…”

Excellent antioxidizing, thermally insulating and flame resistance silica‐polybenzoxazine aerogels for aircraft ablative materials

“…Polybenzoxazine (PBO) is a new type of phenolic resin, which contains six-membered heterocycles of N and O elements and has outstanding strength and high char rate through adjusting the molecular structure, [7][8][9][10] also, possesses the advantages of a simple preparation process and low cost. [11][12][13] Therefore, PBO has become an active research topic as a matrix for thermal protection materials.…”