Synthesis and properties of a novel high temperature pyridine‐containing phthalonitrile polymer

Abstract

A novel pyridine-containing aromatic phthalonitrile monomer, 2,6-bis [4-(3,4-dicyanophenoxy)benzoyl]pyridine (BCBP) was synthesized from the nitro displacement of 4-nitrophthalonitrile by the phenoxide of 2,6-bis (4-hydroxybenzoyl)pyridine (BHBP). 4-(Aminophenoxy) phthalonitrile (APPH) was selected to promote the curing reaction, and the curing behavior has been investigated by differential scanning calorimetric (DSC), suggesting a wide processing window about 64 8C. Different curing additive concentrations resulted in polymers with different crosslinking degrees and subsequently influenced the performance of resins. The resulting BCBP polymer exhibited high glass transition temperatures exceeding 400 8C, outstanding thermo-oxidative stability with weight retention of 95% at 530 8C, indicating a significant improvement in thermal properties endowed by pyridine units. Additionally, it also showed a lower overall water absorption after submersion in boiling water for 50 hours.

Copolymerization modification: improving the processability and thermal properties of phthalonitrile resins with novel comonomers

“…The combined effects together lead to a storage modulus of the 55 mole ratio sample lower than that of the 37 mole ratio sample. Additionally, as presented in Table , all of the data showed far higher storage modulus relative to resorcinol‐based phthalonitrile containing aromatic ether phosphine oxide units, and pyridine‐containing phthalonitrile polymers …”

“…Usually, curing agents are employed to accelerate the polymerization of phthalonitrile resins to obtain desirable performance. Thus, research on curing agents and their mechanism of action has always been a concern . Typical curing agents are Lewis acids and aromatic diamines.…”

“…Recently, with the development of military and aerospace applications, the requirements for the high‐temperature performance of polymer materials are increasingly high . In order to meet such requirements, it is necessary to further enhance the performance of phthalonitrile resins.…”

Branched phenyl‐s‐triazine moieties to enhance thermal properties of phthalonitrile thermosets

“…Notably, the tan δ and loss modulus of the polymer peaked at around 480 °C, revealing a very high T g . Compared with PN oligomers like BCBP, BDCN, 2CN‐PEEK, TDPE and 1,6‐BDCN, T g of the b ‐PBP‐Ph15 network is higher than that of most PN thermosets. The reason can be interpreted as that T g depends on several factors such as chemical structure and crosslinked state.…”

“…Recently, a focus in the development of PN resins has been the modification of their thermal resistance . Thermostable moieties such as heterocyclic pyridine moieties, aromatic naphthyl structures,, silane‐bearing structures and s ‐triazine units, , have been separately introduced to PN oligomer backbones. Some of the cured resins exhibit glass transition temperatures ( T g ) exceeding 400 °C.…”