An efficient approach to prepare ether and amide-based self-catalyzed phthalonitrile resins

Abstract

Phthalonitrile polymers with amide and ortho-, meta-, and para-substituted ether linkages in the backbone were synthesized successfully and their thermal properties were investigated. The monomer building blocks for these polymers were cured without the addition of catalysts due to the self-catalyzing nature of the monomer's amino group. The ether and amide functionalities in the chain enhanced their processability without compromising thermal stability. The resins exhibited a low complex viscosity over a wide processing window between the monomer melting temperature and the polymer cure temperature, with the processing temperature range varying significantly for para-, ortho-, and meta-substituted polymer architectures. All three systems exhibited high thermal and thermo-oxidative stability. The high char yields, which ranged from 66-75% at 900 °C under nitrogen atmosphere, and the high glass transition temperatures of the polymers indicate a high crosslinking density in the network structure.

Systematic study on highly efficient Thermal Synergistic Polymerization effect between alicyclic imide moiety and phthalonitrile: Scope, Properties and Mechanism

“…For procedure (b), no obvious T g are observed in the range of 500 °C for both molar ratio samples. With longer exposure at 375 °C, the samples have progressed to afford a resin with a high crosslink density (Table S1) and M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT mechanical properties reflecting its glassy state over the entire temperature range of the measurements, which shows that the cured polymers have excellent thermal properties, compared with other phthalonitrile polymers [2,4,6,[24][25][26]. The thermal and thermal-oxidative properties of the cured CC/CN blends at different cured extents with different molar ratios were evaluated up to 800 °C in TGA chamber at a heating rate of 10 °C/min under nitrogen and air atmosphere.…”

“…The CC/CN system was chosen to fully characterize the cure behavior and properties of the derived polymers. The cured polymers showed comparable or even higher thermal oxidation stability with almost no voids compared with that of the phthalonitrile resins promoted by traditional curing system of active hydrogen [2,4,[24][25][26]. Additionally, water absorbance at boiling condition and dielectric constant were characterized.…”

“…The char yields of all samples were found to be 0.0~0.8 % after heated to 800 °C. On the other hand, both of the cured polymers 55-ppc and 37-ppc did not exhibit obvious weight loss before the scanning temperature reached 450 °C in air atmosphere, similarly in N 2 atmosphere, while undergoing catastrophic weight loss between 600 °C and 750 °C in air atmosphere, implying superior performance in thermal-oxidative stability [9,[24][25][26]. The fractured cross section morphologies of 55-ppc and 37-ppc were studied by FE-SEM.…”

Enhanced thermal properties of phthalonitrile networks by cooperating phenyl-s-triazine moieties in backbones

“…This means the process window of the 5/6 mixture is about 70e88 C relying on the diamine inclusion. The values are comparable to those of many phthalonitrile monomers such as BZBPh [19b], 3b-c [39], and 4M-P [3b], but still lower than those of the RTM-processable resins like RPh [7a], N ¼ 2 [33], TDPE [13b], and HSiPN-ViSiPN [17] (see Table S5, column Process window). After gelation, the viscosity of the mixture increased abruptly as soon as the temperature was elevated to 275 C. Intriguingly, the viscosity then exhibited a steady trend from 300 C to 350 C, possibly because the increasing temperature generally drives the viscosity declined, simultaneously suppresses the curing rate (see Fig.…”

“…The fact is ascribed to the corresponding increase of the cross-linking density driven by the increasing 6 inclusion. Furthermore, owing to the presence of the thermally stable phenyl-s-triazine units in the polymer backbone, these thermal data are higher than those of many cured poly(aryl ether)-based phthalonitrile networks (e.g., PAEK-CN [40], PEN-t-BAPh [21a], , and also several oligomers disclosed by Keller [3f,9,33,41]), the ether-linked monomers (e.g.,BDS [42], BPh, BAPh, 6FPH [15b], RPh [7a], and monomers 1e3 [16b]), and the self-curable monomers (e.g.,2OeP [16a], 3a-b [39], and 4O-M [3b]), but slightly lower than those of the cured TDPE [13b] and silane-bearing HSiPN-ViSiPN [17] (The corresponding thermal data of the reported networks are summarized in Table S5). However, a certain length of the molecular chain of 5 lowers the cross-linking density of 7 as compared to the above mentioned phthalonitrile monomers, which weakens the role of phenyl-s-triazine groups, in turn to lower the thermal stabilities of (7) after cured with different mass ratios of 6 under N 2 atmosphere.…”