Self‐catalyzed silicon‐containing phthalonitrile resins with low melting point, excellent solubility and thermal stability

Abstract

A series of silicon‐containing self‐catalyzed phthalonitrile derivatives (SiPNs) have been successfully synthesized from reaction of 4‐(4‐aminophenoxy)phthalonitrile (APN) with corresponding chlorosilanes. The chemical structures of the SiPNs were confirmed by spectroscopic techniques. The introduction of silicon‐containing unit into the phthalonitrile structure has dramatically decreased the melting point from 143°C for APN to 40–60°C for the new SiPNs, which also exhibit improved solubility and are soluble in many common solvents. Differential scanning calorimetry analysis showed that they possess the self‐catalyzed behavior with the temperature of exothermic peak due to the self‐catalyzed reaction between 255 and 281°C. The cured SiPNs exhibit excellent thermal stability with glass transition temperature above 450°C, the temperature of 5% weight loss in range of 535–570°C under nitrogen, and 543–562°C under air. Their char yields at 1000°C are in the range of 80.2–82.6% in nitrogen, and 10.1–12.5% in air, respectively. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40919.

Mechanical and thermal properties of phthalonitrile resin reinforced with silicon carbide particles

“…Thus, phthalonitrile monomers containing aromatic ether, bisphenol-A, imide, thioether, and sulfone linkages between the terminal phthalonitrile units have been studied [9][10][11][12][13][14]. The second path was the study of the polymerization process which involves using the proper curing agent among the organic amines, strong organic acids, organic acids/amine salts, metallic salts and metals [15][16][17][18][19], or developing monomers which can be self-catalyzed [20][21][22][23][24][25]. The third one concerns the studies of the phthalonitrile resins as a matrix for composites.…”

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.…”

“…For instance, sterically rotatable meta, ortho-position bisphenoxyl moieties [16] along with flexible alkyl-centertrisphenoxyl [13b] and silane [17] structures were separately introduced to bind with phthalonitrile groups to generate monomers with low-melting point, wide processing window and excellent thermal properties. These monomers were competent to face more cost-effective processing methods such as resin transfer molding (RTM), resin infusion molding (RIM), and vacuum-assisted resin transfer molding (VARTM).…”

Reduced curing kinetic energy and enhanced thermal resistance of phthalonitrile resins modified with inorganic particles

“…Tremendous progress of novel high‐performance materials has been achieved in the last few decades . As one of them, the phthalonitrile resins (PN) were developed by the United States Naval Research Laboratory more than 30 years ago . Because of exceptional properties such as outstanding thermal and thermooxidative stability, excellent mechanical properties, fire resistant performance, and good moisture property, the phthalonitrile resins and their composites are supposed to be the most suitable materials for those harsh application conditions .…”