Highly thermostable rigid-rod networks constructed from an unsymmetrical bisphthalonitrile bearing phthalazinone moieties

Abstract

Phthalazinone rigid-rod networks with excellent thermostability have been prepared by the polyaddition of an unsymmetrical phthalonitrile-functional phthalazinone, namely 4-(4-(4-(3,4-dicyanophenoxy)phenyl)-1-oxophthalazin-2(1H)-yl)phthalonitrile (5) in the presence of promoting agents. 5 was readily prepared via nucleophilic displacement of 4-(4-hydroxylphenyl)(2H)-phthalazin-1-one (1) with 4-nitrophthalonitrile (3) under mild conditions. The substitution of N-H in phthalazinone was accomplished via a novel N-C coupling reaction in an essentially quantitative yield, confirmed by spectroscopic studies as well as a model reaction of 4-(4-tolyl)(2H)-phthalazin-1-one (2). Green prepolymers (7a-7c) were obtained by the polymerization of 5 in its melt phase with the charge of aromatic diamines (6a-6c), and with concurrent cyclization a mixture of poly(iminoisoindolenine) oligomers was produced. The obtained amorphous 7a-7c show T g s ranging from 180 to 190 C depending on the amine nature. Both 5 and 7a-7c have a non-coplanar conformation and exhibit sufficiently good solubility in common solvents (e.g., DMSO, DMF, DMAc, NMP, CHCl 3 , etc.), and hence can be processed either from their melt or from solution. The insoluble networks (8a-8c) prepared by direct curing of 5 or by post-curing of 7a-7c exhibit excellent thermal properties together with superior long-term thermo-oxidative stabilities.

Self-promoted phthalimide-containing phthalonitrile resins with sluggish curing process and excellent thermal stability

“…The PIPN did not show a distinctive increase in viscosity within 150 min dwell at 325 C, 300 min at 305 C, and 450 min at 295 C. On the other hand, the viscosities of PIPN increased rapidly aer 160 min dwell at 325 C, 350 min at 305 C, and 500 min at 295 C. Based on this study, the polymerization of PIPN is an extremely slower process comparing with the polymerization process of phthalonitrile which is promoted by aromatic amines or aromatic phenols, 4,7,14 but it is a faster process comparing with the corresponding model compound BIPN (Fig. 4,13,15 However, for the AHCH, due to their amphoteric nature, the relationship between structures and reactivities is still a puzzle. 7 It has been proposed that the initial curing reaction occurs via the protonation of cyano group nitrogen followed by nucleophilic attack by base at the carbon (Scheme 2).…”

“…The DSC rst and second scan of PIPN monomer are shown in Fig. 13 Neither curve showed any thermal effects at elevated temperatures due to curing, which indicated that the polymerization of PIPN proceeded extremely sluggish and showed very low polymerization exothermic effect. The rst scan of DSC thermogram exhibited a smaller endotherm around 156 C and a bigger endotherm around 210 C, corresponding to loss of crystalline water and melting transition of PIPN monomer, respectively.…”

A Luminescent Hypercrosslinked Conjugated Microporous Polymer for Efficient Removal and Detection of Mercury Ions

“…Meanwhile, the obtained product is efficiently recoverable in most common organic solvents such as dimethyl sulfoxide (DMSO), N,N ‐dimethylformamide (DMF), N,N ‐dimethylacetamide (DMAc), N ‐methylpyrroli‐done (NMP), tetrahydrofuran (THF), and even diluted HCl solution (10 wt%), implying a physical–chemical stable nature. The excellent thermal and chemical stabilities of HCMP‐1 are most possibly resulted from the high charge transfer interactions between the 1,3,5‐triazine rings and aromatic/heterocyclic units . The immiscible network avoids unnecessary contamination to the detection system, being more convenient for extraction and separation of the probes relative to the small molecular ones.…”

Synthesis, curing kinetics and thermal properties of a novel self-promoted fluorene-based bisphthalonitrile monomer

“…These unique characteristics give the phthalonitrile resins a wide range of applications in marine, aerospace and microelectronic industries [5][6][7]. However, the polymerization of the neat phthalonitrile monomer is extremely difficult, requiring several days at elevated temperature before the gelation process occurs, which limits their wide uses and exaggerates its cost.…”