Hyperbranched cyclic and multicyclic polymers by “a2+b4” polycondensations

At first, theoretical aspects of “a₂+b₄” polycondensations (meaning polycondensations of difunctional and tetrafunctional monomers) are discussed and compared with what is known about “a₂+b₃” polycondensations. The following review of experimental results is subdivided into three sections. First, syntheses of hyperbranched polyethers and polyesters by polycondensations based on equimolar feed ratios will be reported. Second, kinetically controlled (i.e., irreversible) syntheses of multicyclic polymers using equifunctional feed ratios (i.e., a₂/b₄ ratios of 2:1) will be described. In the third section, syntheses of multicyclic polymers via thermodynamically controlled (reversible) “a₂+b₄” polycondensations will be discussed. Characteristic for these polycondensations are again equifunctional feed ratios and metal alkoxides as “a₂” or “b₄” monomers, which catalyze rapid equilibration reactions. Finally, potential applications of the new polymers will shortly be mentioned. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1971–1987, 2009     

New succinyl‐spaced pyrazoles: Regioselective synthesis of 1,4‐bis[5‐(trichloromethyl)‐1H‐pyrazol‐1‐yl]butane‐1,4‐diones

The facile and convenient access by a conventional procedure in ethanol as solvent to a new series of succinyl‐spaced pyrazoles including 1,4‐bis[5‐(trichloromethyl)‐5‐hydroxy‐4,5‐dihydro‐1H‐pyrazol‐1‐yl]butane‐1,4‐diones (64–82%) and the respective dehydrated derivatives as 1,4‐bis[5‐(trichloromethyl)‐1H‐pyrazol‐1‐yl]butane‐1,4‐diones in 57–82% yields, from the regioselective cyclocondensation reactions of 4‐substituted 4‐methoxy‐1,1,1‐trichloroalk‐3‐en‐2‐ones with succinic acid dihydrazide, where the 4‐substituents are Me, Ph, 4‐FC₆H₄, 4‐ClC₆H₄, 4‐NO₂C₆H₄, 2‐furyl, and 2‐thienyl, is reported. J. Heterocyclic Chem., 2011.     

Allyl-containing polyaryl ethers with perfluorinated mono- and biphenylene fragments

A method for the synthesis of fluorinated allyl-containing bisphenol based on 4,4′-[(2,3,5,6-tetrafluoro-1,4-phenylene)bis(oxy)]diphenol has been elaborated. Curable aromatic polyethers have been prepared via polycondensation of the synthesized bisphenol with decafluorobiphenyl. The influence of bases, namely K₂CO₃ and NaH, on the molecular weights of polymers has been studied, and the conditions of their curing at allyl moieties have been found. Mechanical, physicochemical, and dielectric properties of allylcontaining polymers are dependent on the method of their preparation and curing.     

Multicyclic polyethers with pendant keto groups by polycondensation of silylated 1,1,1‐tris(4‐hydroxyphenyl)ethane

1,1,1‐Tris(4‐trimethylsiloxyphenyl)ethane, (silylated THPE), was polycondensed with 2,4‐difluoroacetophenone and 2,4‐difluorobenzophenone. All polycondensations were performed in N‐methylpyrrolidone with K₂CO₃ as promotor. The feed ratio THPE/difluoroaromat was varied from 1.0:1.3 to 1.0:1.5. Instead of hyperbranched polymers or gels, soluble multicyclic oligo‐ and polyethers were identified as main reaction products by MALDI‐TOF mass spectrometry in all experiments. At feed ratios around 1.0:1.5 multicycles free of functional group were the main products. However, when isomeric a₂‐monomers such as 2,6‐difluoroacetophenone, 2,6‐difluorobenzophenone (or 2,6‐difluorodiphenylsulfone) were used, gelation occurred at feed ratios as low as 1.0:1.1. An explanation of the different cyclization tendencies on the basis of different conformations is discussed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6233–6246, 2005     

Pd(0)‐catalyzed polyaddition of bifunctional vinyloxiranes with phenol derivatives: The synthesis of polymers containing an allyl aryl ether moiety in the main chain

The palladium(0)‐catalyzed polyaddition of bifunctional vinyloxiranes [1,4‐bis(2‐vinylepoxyethyl)benzene ( 1a ) and 1,4‐bis(1‐methyl‐2‐vinylepoxyethyl)benzene ( 1b )] with oxygen nucleophiles such as hydroquinone and bisphenol A gave new unsaturated polyethers containing an allyl aryl ether moiety and pendant hydroxy groups. The polyaddition with 1a was largely affected by the phosphine ligands employed and the reaction temperature. The polyaddition with hydroquinone and bisphenol A was conducted at room temperature for 24 h in tetrahydrofuran in the presence of PPh₃ and gave the desired polyethers in good yields, the number‐average molecular weights (M_n) of which were 5700 and 7700, respectively. 1,2‐Bis(diphenylphosphino)ethane (dppe) was not effective in the polyaddition with 1a . The polyaddition of 1b with hydroquinone and bisphenol A gave the corresponding polyethers despite the kinds of ligands employed (PPh₃ and dppe), contrary to the polyaddition with 1a . The polyaddition of 1b with 4,4′‐biphenol was also carried out in the presence of Pd₂(dba)₃ · CHCl₃/dppe as a catalyst (where dba is dibenzylideneacetone) and afforded the expected polyether with a high M_n value (M_n = 24,900). In addition, vinyloxirane 1b could reacted with racemic 1,1′‐bi‐2‐naphthol to give the corresponding polyether in a good yield. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 476–482, 2003     

N‐(2‐Hydroxyethyl)‐N‐methyldithiocarbamato Complexes of Nickel(II) with Phosphorus Donor Ligands

Planar nickel(II) complexes involving N‐(2‐Hydroxyethyl)‐N‐methyldithiocarbamate, such as [NiX(nmedtc)(PPh₃)] (X = Cl, NCS; PPh₃ = triphenylphosphine), and [Ni(nmedtc)(P‐P)]ClO₄(P‐P = 1,1‐bis(diphenylphosphino)methane(dppm); 1,3‐bis(diphenylphosphino)propane (1,3‐dppp); 1,4‐bis(diphenylphosphino)butane(1,4‐dppb) have been synthesized. The complexes have been characterized by elemental analyses, IR and electronic spectroscopies. The increased νC–N value in all the complexes is due to the mesomeric drift of electrons from the dithiocarbamate ligands to the metal atom. Single crystal X‐ray structure of [Ni(nmedtc)(1,3‐dppp)]ClO₄·H₂O is reported. In the present 1,3‐dppp chelate, the P–Ni–P angle is higher than that found in 1,2‐bis(diphenylphosphino)ethane‐nickel chelates and lower than 1,4‐bis(diphenylphosphino)butane‐nickel chelates, as a result of presence of the flexible propyl back bone connecting the two phosphorus atoms of the complex.     

Biodegradable polymers based on renewable resources. VII. Novel random and alternating copolycarbonates from 1,4:3,6‐dianhydrohexitols and aliphatic diols

Novel copolycarbonates containing 1,4:3,6‐dianhydro‐D ‐glucitol or 1,4:3,6‐dianhydro‐D ‐mannitol units, with various methylene chain lengths, were synthesized by bulk and solution polycondensations, of several combinations of carbonate‐modified sugar derivatives and aliphatic diols. Bulk polycondensations of 1,4:3,6‐dianhydro‐2,5‐bis‐O‐(phenoxycarbonyl)‐D ‐glucitol or 1,4:3,6‐dianhydro‐2,5‐bis‐O‐(phenoxycarbonyl)‐D ‐mannitol with four α,ω‐alkanediols having methylene chain lengths of 4, 6, 8, and 10, respectively, at 180 °C afforded the corresponding copolycarbonates with number‐average molecular weight (M_n) values up to 19.₂ × 10³. ¹³C NMR analysis disclosed that these polymers had scrambled structures in which the sugar carbonate and aliphatic carbonate moieties were nearly randomly distributed along a polymer chain. However, solution polycondensations between 1,4:3,6‐dianhydro‐2,5‐bis‐O‐(p‐nitrophenoxycarbonyl)‐D ‐glucitol or 1,4:3,6‐dianhydro‐2,5‐bis‐O‐(p‐nitrophenoxycarbonyl)‐D ‐mannitol, and the α,ω‐alkanediols in sulfolane or dimethyl sulfoxide at 60 °C gave well‐defined copolycarbonates having regular structures consisting of alternating sugar carbonate and aliphatic carbonate moieties with M_n values up to 33.₈ × 10³. Differential scanning calorimetry demonstrated that all the copolycarbonates were amorphous with glass‐transition temperatures ranging from 1 to 65 °C, which decreased with increasing lengths of the methylene chain of the aliphatic diols. Additionally, all the copolycarbonates were stable up to 310–330 °C as estimated by thermogravimetric analysis. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2312–2321, 2003     

Effect of central spacer chain structure on cationic cyclopolymerization tendency of divinyl ethers

To clarify the effects of the central spacer chain structure of divinyl ethers on their cationic cyclopolymerization tendencies, 1,4‐bis[(2‐vinyloxy)ethoxy]benzene ( 1 ), 1,4‐bis[(2‐vinyloxy)ethoxy]butane ( 2 ), 1,6‐bis[(2‐vinyloxy)ethoxy]hexane ( 3 ), 1,8‐bis[(2‐vinyloxy)ethoxy]octane ( 4 ), and 1,4‐bis[(4‐vinyloxy)butoxy]butane ( 5 ) were polymerized with the hydrogen chloride/zinc chloride (HCl/ZnCl₂) initiating system in methylene chloride (CH₂Cl₂) at 0 °C at low initial monomer concentration ([M]₀ = 0.15 M). The polymerizations of divinyl ethers 2 and 3 gave soluble polymers quantitatively. In contrast, the polymerizations of divinyl ethers 1 , 4 , and 5 underwent gel formation at high monomer conversion. The content of the unreacted vinyl groups of the obtained soluble polymers was measured by ¹H NMR spectroscopy. Judging from the relatively low vinyl contents of the polymers produced even in the early stage of the polymerization (monomer conversion < ～20%), the cyclopolymerization occurred to some extent for 2 , 3 , and 4 . On the contrary, the polymers produced from 1 and 5 exhibited the relatively high vinyl content, indicating that the cyclopolymerization tendencies of 1 and 5 were lower than those of 2 , 3 , and 4 . These results are discussed in terms of the structural variety of the spacer chains: (1) the presence of benzene ring ( 1 vs 2 ), (2) their length ( 2 vs 3 and 4 ), and (3) the position of ether oxygen ( 4 vs 5 ). © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4002–4012, 2002     

Manganese(II) and cobalt(II) complexes of 1,4‐bis(diphenylphosphinoyl)butane

The title complexes, catena‐poly[[[diaquadiethanolmanganese(II)]‐μ‐1,4‐bis(diphenylphosphinoyl)butane‐κ²O:O′] dinitrate 1,4‐bis(diphenylphosphinoyl)butane solvate], {[Mn(C₂H₆O)₂(C₂₈H₂₈O₂P₂)(H₂O)₂](NO₃)₂·C₂₈H₂₈O₂P₂}_n, (I), and catena‐poly[[[diaquadiethanolcobalt(II)]‐μ‐1,4‐bis(diphenylphosphinoyl)butane‐κ²O:O′] dinitrate 1,4‐bis(diphenylphosphinoyl)butane solvate], {[Co(C₂H₆O)₂(C₂₈H₂₈O₂P₂)(H₂O)₂](NO₃)₂·C₂₈H₂₈O₂P₂}_n, (II), are isostructural and centrosymmetric, with the M^II ions at centres of inversion. The coordination geometry is octahedral, with each metal ion coordinated by two trans ethanol molecules, two trans water molecules and two bridging 1,4‐bis(diphenylphosphinoyl)butane ligands which link the coordination centres to form one‐dimensional polymeric chains. Parallel chains are linked by hydrogen bonds to uncoordinated 1,4‐bis(diphenylphosphinoyl)butane molecules, which are bisected by a centre of inversion. Further hydrogen bonds, weak C—H...O interactions to nitrate anions, and weak C—H...π interactions serve to stabilize the structure. This study reports a development of the coordination chemistry of bis(diphenylphosphinoyl)alkanes, with the first reported structures of complexes of the first‐row transition metals with 1,4‐bis(diphenylphosphinoyl)butane.     

Poly(ε‐caprolactone) by combined ring‐opening polymerization and azeotropic polycondensation—the role of cyclization and equilibration

Using three different catalysts, water‐initiated polymerizations of ε‐caprolactone were conducted in bulk with variation of the monomer/water ratio. The resulting CH₂OH and CO₂H‐ terminated polylactones were subjected in situ to azeotropic polycondensations. With Bi‐triflate and temperatures, the polycondensations were not much successful and involved side reactions. With ZnCl₂, and especially SnCl₂, considerably higher molar masses were achieved. The substitution of toluene for chlorobenzene for refluxing gave better results. The polycondensations broadened the molar mass distribution of the ROP‐based prepolymers, and polydispersities between 1.4–1.8 were obtained. The MALDI–TOF mass spectra revealed that the polycondensations significantly enhanced the fraction of rings due to efficient “end‐biting” reactions. By comparison with copolymerization experiments and Sn methoxide‐initiated polymerizations, it was demonstrated that equilibration reactions, such as the formation of rings by “back‐biting,” did not occur. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

cis‐[1,4‐Bis(di­phenyl­phosphino)­butane](μ‐tetra­thio­tungstato)­palladium(II) N,N′‐di­methyl­form­amide hemisolvate hemihydrate

In the title compound, [1,4‐bis(di­phenyl­phosphino)­butane‐2κ²P,P′]­di‐μ‐thio‐1:2κ⁴S‐di­thio‐1κ²S‐palladium(II)­tung­sten(VI) N,N′‐di­methyl­form­amide hemisolvate hemihydrate, [PdWS₄­(C₂₈H₂₈P₂)]·0.5C₃H₇NO·0.5H₂O, the Pd atom is coordinated by two S atoms from the distorted‐tetrahedral [WS₄]²⁻ anion and two P atoms from the dppb mol­ecule [dppb is 1,4‐bis(di­phenyl­phos­phino)­butane] in an approximately square‐planar configuration. A puckered seven‐membered ring is formed by the Pd atom and the dppb ligand.     

Hydrolysis of aromatic polyurethane in water under high pressure of CO2

We have demonstrated a hydrolysis reaction of polyurethane (PU) under high pressure of carbon dioxide (CO₂) in water. We employed the PU sample, poly(methylene bis‐(1,4‐phenylene)hexamethylene dicarbamate), denoted as M‐PU, which was synthesized from 4,4′‐diphenyl methane diisocyanate and 1,4‐butane diol (BD). The optimum hydrolysis reaction condition was 190 °C under CO₂ pressures over 4.1 MPa in water medium, and 93% hydrolysis of M‐PU was achieved. After the reaction, the water‐soluble parts were obtained, and isolated by column chromatography. The isolated products were 4,4′‐methylenedianiline (MDA) and 1,4‐butane diol (BD), which were components of repeating unit of M‐PU. In addition, the hydrolysis reaction gave no byproduct. This hydrolysis under high pressure of CO₂ with water is a reaction by which M‐PU is selectively hydrolyzed into MDA and BD by cleaving urethane linkage. Moreover, the resulting hydrolyzed products were easily obtained by evaporation of aqueous layer after the reaction, indicating an efficient chemical recycling of PU was achieved. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2004–2010     

Rhodium‐Catalyzed 1,4‐Addition of Lithium 2‐Furyltriolborates to Unsaturated Ketones and Esters for Enantioselective Synthesis of γ‐Oxo‐Carboxylic Acids By Oxidation of the Furyl Ring with Ozone

Rhodium‐catalyzed 1,4‐addition of lithium 5‐methyl‐2‐furyltriolborate ([ArB(OCH₂)₃CCH₃]Li, Ar=5‐methyl‐2‐furyl) to unsaturated ketones to give β‐furyl ketones was followed by ozonolysis of the furyl ring for enantioselective synthesis of γ‐oxo‐carboxylic acids. [Rh(nbd)₂]BF₄ (nbd=2,5‐norbornadiene) chelated with 2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl (binap) or 2,3‐bis(diphenylphosphino)butane (chiraphos) gave high yields and high selectivities in a range of 91–99 % ee at 30 °C in a basic dioxane/water solution. The corresponding reaction of unsaturated esters, such as methyl crotonate, had strong resistance under analogous conditions, but the 1,4‐adduct was obtained in 70 % yield and with 94 % ee when more electron‐deficient phenyl crotonate was used as the substrate.     

Co‐MOFs Containing Flexible α,ω‐Alkane‐dicarboxylates and Bis(imidazole) Ligands: Synthesis,Structure, and Properties

Three structurally related flexible bis(imidazole) ligands reacted with Co(NO₃)₂ · 6H₂O and succinic acid (L₁) to yield three new metal‐organic frameworks {[Co(L₁)(L₂)] · (H₂O)}_n ( 1 ) [L₂ = 2‐bis(imidazol‐1‐yl)ethane], {[Co(L₁)(L₃)](H₂O)}_n ( 2 ) [L₃ = 1,4‐bis(imidazol‐1‐yl) butane], and {[Co(L₁)(L₄)] · (H₂O)}_n ( 3 ) [L₄ = 1,4‐bis(2‐methyl‐imidazol‐1‐yl)butane], respectively. These complexes were synthesized under solvothermal conditions and characterized by elemental analysis, IR spectroscopy, single‐crystal and powder X‐ray diffraction, as well as thermal analyses. Interestingly, the ligands in these complexes exhibit different conformations and further cause three different configurations. Complex 1 shows a three‐dimensional (3D) framework, which is connected by two‐dimensional (2D) layer structures through hydrogen bonds. Complex 2 is a diamond structure with threefold interpenetration. Complex 3 is a 3D framework linked by hydrogen bonds like complex 1 .     

Metal‐Free‐Mediated Oxidation Aromatization of 1,4‐Dihydropyridines to Pyridines Using Visible Light and Air

A metal‐free and environmentally friendly aerobic aromatization photosensitized by organic dye eosin Y bis(tetrabutyl ammonium salt) (TBA‐eosinY) has been developed. With the aid of K₂CO₃, the aerobic catalytic system converts 1,4‐dihydropyridines to their corresponding pyridine derivatives efficiently under visible light irradiation (λ=450 nm) at room temperature.     

Bipodal 1,1′‐acyl‐3,3,3′,3′‐tetraalkylbis(thiourea) ligands with flexible C3, C4 and C6 spacer groups

In the structures of 3,3,3′,3′‐tetraethyl‐1,1′‐(propane‐1,3‐diyldicarbonyl)bis(thiourea), C₁₅H₂₈N₄O₂S₂, (I), 3,3,3′,3′‐tetraethyl‐1,1′‐(butane‐1,4‐diyldicarbonyl)bis(thiourea), C₁₆H₃₀N₄O₂S₂, (II), and 3,3,3′,3′‐tetrabutyl‐1,1′‐(hexane‐1,6‐diyldicarbonyl)bis(thiourea), C₂₆H₅₀N₄O₂S₂, (III), compound (I) displays resonance‐assisted hydrogen bonding, (II) exhibits an inversion centre, and both (II) and (III) are characterized by intermolecular hydrogen bonds between the carbonyl O atoms and thioamide H atoms, leading to chains of hydrogen‐bonded molecules throughout the structures. The accurate structural data for these molecules is expected to assist in molecular modelling and other studies currently in progress.     

Efficient Preparation of 2, 2′‐Disubstituted‐3, 3′‐(1, 4‐phenylene)bis‐thienopyrimidin‐4‐ones Based on an aza‐Wittig Reaction

Tandem aza‐Wittig reaction of iminophosphorane with 1, 4‐phenylene diisocyanate followed by intramolecular heteroconjugate addition annulation after addition of a nucleophilic reagent (amine, phenol, and alcohol), in the presence of catalytic K₂CO₃ or NaOR, gives selectively the functionalized substituted 2, 2′‐di(alkylamino, aryloxy)‐3, 3′‐(1, 4‐phenylene)bis(thieno[3, 2‐d]pyrimidin‐4(3H)‐ones) and 2, 2′‐di(alkylamino or alkoxy)‐3, 3′‐(1, 4‐phenylene)bis(3, 5, 6, 7‐tetrahydro‐4H‐cyclopenta[4, 5]thieno[2, 3‐d]pyrimidin‐4‐ones).     

A novel two‐dimensional CuSCN network templated by 2,2′‐dimethyl‐1,1′‐(butane‐1,4‐diyl)bis(1H‐imidazol‐3‐ium) cations

The cation‐templated self‐assembly of 1,4‐bis(2‐methyl‐1H‐imidazol‐1‐yl)butane (bmimb) with CuSCN gives rise to a novel two‐dimensional network, namely catena‐poly[2,2′‐dimethyl‐1,1′‐(butane‐1,4‐diyl)bis(1H‐imidazol‐3‐ium) [tetra‐μ₂‐thiocyanato‐κ⁴S:S;κ⁴S:N‐dicopper(I)]], {(C₁₂H₂₀N₄)[Cu₂(NCS)₄]}_n. The Cu^I cation is four‐coordinated by one N and three S atoms, giving a tetrahedral geometry. One of the two crystallographically independent SCN⁻ anions acts as a μ₂‐S:S bridge, binding a pair of Cu^I cations into a centrosymmetric [Cu₂(NCS)₂] subunit, which is further extended into a two‐dimensional 4⁴‐sql net by another kind of SCN⁻ anion with an end‐to‐end μ₂‐S:N coordination mode. Interestingly, each H₂bmimb dication, lying on an inversion centre, threads through one of the windows of the two‐dimensional 4⁴‐sql net, giving a pseudorotaxane‐like structure. The two‐dimensional 4⁴‐sql networks are packed into the resultant three‐dimensional supramolecular framework through bmimb–SCN N—H...N hydrogen bonds.     

Two new cadmium(II) coordination polymers based on bis(1,2,4‐triazol‐1‐yl)alkane ligands and pyrazine‐2,3‐dicarboxylic acid

Assemblies of pyrazine‐2,3‐dicarboxylic acid and Cd^II in the presence of bis(1,2,4‐triazol‐1‐yl)butane or bis(1,2,4‐triazol‐1‐yl)ethane under ambient conditions yielded two new coordination polymers, namely poly[[tetraaqua[μ₂‐1,4‐bis(1,2,4‐triazol‐1‐yl)butane‐κ²N⁴:N^4′]bis(μ₂‐pyrazine‐2,3‐dicarboxylato‐κ³N¹,O²:O³)dicadmium(II)] dihydrate], {[Cd₂(C₆H₂N₂O₄)₂(C₈H₁₂N₆)(H₂O)₄]·2H₂O}_n, (I), and poly[[diaqua[μ₂‐1,2‐bis(1,2,4‐triazol‐1‐yl)ethane‐κ²N⁴:N^4′]bis(μ₃‐pyrazine‐2,3‐dicarboxylato‐κ⁴N¹,O²:O³:O^3′)dicadmium(II)] dihydrate], {[Cd₂(C₆H₂N₂O₄)₂(C₆H₈N₆)(H₂O)₂]·2H₂O}_n, (II). Complex (I) displays an interesting two‐dimensional wave‐like structure and forms a distinct extended three‐dimensional supramolecular structure with the help of O—H...N and O—H...O hydrogen bonds. Complex (II) has a three‐dimensional framework structure in which hydrogen bonds of the O—H...N and O—H...O types are found.     

Synthesis and properties of a bisphenol A based phthalonitrile resin

A multiple aromatic ether linked phthalonitrile was synthesized and characterized. The oligomeric phthalonitrile monomer was prepared from the reaction of an excess amount of bisphenol A with 4,4′‐difluorobenzophenone in the presence of K₂CO₃ as the base in an N,N‐dimethylformamide/toluene solvent mixture, followed by end capping with 4‐nitrophthalonitrile in a two‐step, one‐pot reaction. The monomer properties were compared to those of the known resin 2,2‐bis[4‐(3,4‐dicyanophenoxy)phenyl]propane after being cured in the presence of bis[4‐(4‐aminophenoxy)phenyl]sulfone. Rheometric measurements and thermogravimetric analysis showed that the oligomeric phthalonitrile resin maintained good structural integrity upon heating to elevated temperatures and exhibited excellent thermal properties along with long‐term oxidative stability. The ether‐linked phthalonitrile resin absorbed less than 2.5% water by weight after exposure to an aqueous environment for extended periods. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4136–4143, 2005