α-sulfonated fatty acid esters: II. Solution behavior of α-sulfonated fatty acid polyethylene glycol esters

Sodium α-sulfonated, fatty acid polyethylene glycol monoesters [C _m H_2m+1CH(SO₃Na)COO(C₂H₄O) _n H] and diesters [C _m H_2m+1CH(SO₃Na)COO(C₂H₄O) _n COCH(SO₃Na)C _m H_2m+1], wherem=10–16 andn=1–35, were prepared by esterification of α-sulfonated, fatty acids with polyethylene glycols, followed by neutralization with NaOH. Crude products were purified by reversed-phase column chromatography on an octadecyl-modified silica gel. Characteristic solution behavior of these α-sulfonated fatty acid esters was, examined, and the following features were observed. All monoesters prepared in this work had Krafft points below 0°C and also possessed good calcium stabilities. Critical micelle concentrations of the monoesters increased monotonously, as a rule, with an increase in the number of oxyethylene units. These results suggest that the polyethylene glycol residue of the monoester behaves as a hydrophile. On the other hand, diesters possessed high water solubility, low foamability, and critical micelle concentrations that were lower by a factor of ten compared to those of the monoesters.     

Hydroformylierung von Buta-1,3-dien und butadienhaltigen Kohlenwasserstoffraktionen nach dem Zweiphasenverfahren

Two-phase Hydroformylation of Buta-1,3-diene and Hydrocarbon Mixtures Containing Buta-1,3-diene The two-phase hydroformylation of buta-1,3-diene with (HRh(CO)[P(m-C₆H₄SO₃Na)₃]₃ the Kuntz catalyst system with excess P(m-C₆H₄SO₃Na)₃) gives high yields of C₅-monoaldehydes. Main product in this mixture is the reactive trans- and cis-pent-3-enal. In consecutive reactions the pent-3-enal is partially hydrogenated to n-pentanal, but also-favoured by the protolytic milieu of the two-phase reaction- aldol condensated to 2-propenylheptadienal. The hydrogenation product of the propenylheptadienal, 2-propylheptanol-1, is a good plasticizer alcohol with a wanted low vapour pressure. Especially promising is the two-phase hydroformylation of the unrefined C₄-fraction of the naphtha pyrolysis: after a more than 95 per cent conversion of the buta-1,3-diene also more than 80 per cent of the n-but-1-ene in the C₄-fraction is hydroformylated mainly to wanted n-pentanal. Less than 5–10% of the n-but-2-enes and the isobutene in the C₄-fraction react under these conditions to oxo-products (2- and 3-methylbutanal). Acetylenic compounds in the C₄-fraction are converted quantitatively into products.     

Reversibly Redox‐Switchable Anionic Surfactant Contains Two Selenium Atoms

To better control the interfacial activities of selenium‐containing surfactants, a redox‐switchable anionic surfactant containing 2 selenium atoms, namely sodium 3‐((3‐(benzylselanyl)propyl)selanyl)propyl sulfate (SBSe₂S), has been designed and synthesized. Upon oxidation by H₂O₂, the 2 divalent selenide groups in the hydrophobic tail of SBSe₂S are converted into the corresponding selenoxides. The initial hydrophobic tail of SBSe₂S gets separated into 3 segments by 2 hydrophilic selenoxide groups, destroying the bola‐type structure. The interfacial activities of SBSe₂S in aqueous solution could thereby be switched off to a greater degree than in the case of its counterparts containing only a single selenium atom. After reduction with Na₂SO₃, the 2 selenoxide groups in SBSe₂S‐Ox are restored to the initial selenide. Consequently, the interfacial activities of SBSe₂S could be reversibly switched by alternate addition of H₂O₂ and Na₂SO₃, without obvious deterioration over 5 cycles.     

Catalytic conversions in water. Part 5: Carbonylation of 1-(4-isobutylphenyl)ethanol to ibuprofen catalysed by water-soluble palladium–phosphine complexes in a two-phase system

1-(4-Isobutylphenyl)ethanol (IBPE) was carbonylated to 2-(4-isobutylphenyl)propionic acid (ibuprofen) in an aqueous/organic two phase system using the water-soluble Pd(tppts)₃ catalyst [tppts = P(C₆H₄-m-SO₃Na)₃] in the presence of p-CH₃C₆H₄SO₃H at 363 K, 15 MPa CO pressure and a palladium concentration of 150 ppm without addition of organic solvents. Under these conditions the conversion of IBPE was 83% and the selectivity to ibuprofen 82% with no decomposition of the Pd(tppts)₃ catalyst. Both the activity and selectivity were strongly influenced by the tppts/Pd molar ratio and the nature of the added Brønsted acid. Maximum efficiency was observed for P/Pd = 10. Acids of weakly or non-coordinating anions, such as p-CH₃C₆H₄SO₃H, CF₃COOH or HPF₆ afforded carbonylation. No catalytic activity was observed in the presence of acids of strongly coordinating anions, such as HI. The water-soluble Pd/dppps catalyst [dppps = Ar_2-nPh_nP-(CH₂)₃-PPh_n′Ar_2-n′; Ar = C₆H₄-m-SO₃Na; n = nń = 0: 86% and n = 0, nń = 1: 14%] exhibited low catalytic activity and the major product obtained was the linear isomer of ibuprofen, 3-(4-isobutylphenyl)propionic acid (3-IPPA) with selectivities up to 78%. Replacement of tppts by a ligand containing less −SO₃Na groups such as monosulphonated triphenylphosphine (tppms) gives rise to a dramatic drop in the catalytic activity and selectivity to ibuprofen. No catalytic activity was observed using palladium catalysts modified with 2-pyridyldiphenylphosphine (PyPPh₂) and tris(2-pyridyl)phosphine (PPy₃) which are both water soluble in their protonated form. A catalytic cycle is proposed to explain the observed results. ©1997 SCI     

Surface oxidation of styrene butadiene copolymers: Study by laser ablation and secondary ion mass spectrometry

The capabilities of ion bombardment and laser ablation coupled to mass spectrometry as independent techniques to investigate the surface thermooxidative stability of polystyrene, polybutadiene polymers, and styrene butadiene rubber (SBR) copolymers were investigated. Surface chemical modifications were detected according to the polymeric structure. The degradation products detected by static secondary ion mass spectrometry appeared at m/z 29, 43, and 55. Their compositions were related to the general formulae C_nH_mO⁺ with n = 1–3 and m = 1–3 for polybutadiene and styrene butadiene copolymers, whereas polystyrene was not affected by the aging treatment. The C_nH_mO⁺ ions result from butadiene unit degradation. The laser ablation ionization Fourier transform ion cyclotron resonance mass‐spectrometry results confirmed the detection of C_nH_mO⁺ ions. Finally, it may be considered that the surface thermooxidative process of SBR copolymers begins with butadiene unit degradation. The development of butadiene unit oxidation showed a dynamic oxidation phase, which coincided with a loss of unsaturation. The influence of the polymer conformation (blocked, branched, and random) on the surface oxidation for 30% styrene SBR compounds was also studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1910–1917, 2003     

High pyroelectric performance in Pb0.99Nb0.02[(Zr0.57Sn0.43)0.94Ti0.06]0.98O3/Al2O3 composites by design

High pyroelectric performance around human body temperature is essential for ultra-sensitive infrared detectors of medical systems. Herein, toward human health monitoring, composite ceramics (1-x)Pb_0.99Nb_0.02[(Zr_0.57Sn_0.43)_0.94Ti_0.06]_0.98O₃/xAl₂O₃ (x = 0, 0.1, and 0.2) were designed. A metastable ferroelectric (FE) phase was induced in the anti-FE matrix by the Al₂O₃ component-induced internal stress, and in turn FE-anti-FE phase boundary was constructed. The ceramics at x = 0.2 exhibit high pyroelectric coefficient with p = 10.9 × 10⁻⁴ C·m⁻²·K⁻¹ and figures of merit with current responsivity F_i = 6.23 × 10⁻¹⁰ m·V⁻¹, voltage responsivity F_v = 12.71 × 10⁻² m²·C⁻¹, and detectivity F_d = 7.03 × 10⁻⁵ Pa^−1/2 around human body temperature. Moreover, the enhanced pyroelectric coefficients exist in a broad operation temperature range with a large full width at half maximums of 18.5°C and peak value of 29.2 × 10⁻⁴ C·m⁻²·K⁻¹ at 48.2°C. The designed composite ceramic is a promising candidate for infrared thermal imaging technology of noncontact human health monitoring system.     

Organoselenium Chemistry. Preparation of Allyl and Homoallyl Amines by Aminomethylation of Phenylseleno-Substituted Allyl Tin Reagents

Metalation of methallyl phenyl selenide, allyl phenyl selenide, and methallyl phenyl sulfide followed by tri-n-butylstannylation gave exclusively the γ-stannylated sulfide or selenide (e.g., 1-phenylseleno-2-methyl-3-tri-n-butylstannyl-1-propene ( 5 )). Compound 5 reacts with a series of immonium electrophiles to give products of aminomethylation α- to selenium. Electrophiles have included N-(bromomethyl)phthalimide/ZnBr₂, Eschenmoser salt (dimethylmethyleneammonium iodide), and Mannich reagents generated in situ from diethylamine, piperidine, isopropyl sarcosinate and benzylmethylamine. The selenide from the last of these amines (N, 3-dimethyl-N-benzyl-2-phenylseleno-3-butenamine, 10 ) has been subjected to further transformations as follows: (1) treatment of 10 with trimethylstannyllithium results in replacement of phenylseleno by stannyl; this allyltin ( 11 ) can then again be aminomethylated giving compound 12 or 13 ; (2) oxidation of 10 gives amino alcohol 14 by [2, 3] sigmatropic rearrangement of the allyl selenoxide; (3) photolysis of 10 results in 1,3-rearrangement of the phenylseleno group; oxidative rearrangement of this allyl selenide gives amino alcohol 16 . The phthalimidomethylation product ( 6 ) is converted to a precursor for the side chain of the cytokinin zeatin by oxidation and [2, 3] sigmatropic rearrangement.     

Poly(di(ω-alkylphenyl)stannane)s

Poly(di(ω-alkylphenyl)stannane)s, [Sn(C _n H_2n Ph)₂] _m with n = 2–4, and a copolymer of di(3-propylphenyl)stannane and dibutylstannane of weight-average molar masses of 2–8 · 10⁴ g/mol were synthesized by dehydropolymerization of stannanes of the composition H₂SnR₂ using Wilkinson’s catalyst [RhCl(PPh₃)₃]. At least two methylene groups were required as spacers between the phenyl group and the tin atom for polymerization to occur. The polystannanes were characterized by, among other techniques, ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopy, thermal analysis and X-ray diffraction. The polymers featured properties different from those of the corresponding poly(dialkylstannane)s. Specifically, the [Sn(C _n H_2n Ph)₂] _m family displayed glass transitions at remarkably low temperatures, down to ca. −50 °C, and a lower value for a copolymer (−68 °C). Polymers [Sn(C_nH_2nPh)₂]_m with n = 2 and 3 and a copolymer at room temperature were of a gel-like concistence, which enabled facile orientation with shear forces. Finally, the temperature-dependent electrical conductivity was determined for poly(di(3-propylphenyl)stannane), which followed the law of typical semiconductors, with an activation energy for conduction of 0.12 eV.     

Combustion characteristics of fatty acid methyl esters derived from recycled cooking oil

The goal of this study is to find out the exhaust emissions differences produced by different kinds of fatty acid methyl esters (FAME) derived from used cooking oils and animal fats, as well as the importance of the purification step in exhaust emissions production. A total of 120 L of waste vegetable oil and 30 L of waste frying oil were collected and converted into three batches of FAME. There were two batches of FAME produced from waste vegetable oil (B01 and B02), and one batch of FAME produced by mixing 2% of waste frying oil with waste vegetable oil (B03). The FAMEs used in this study had higher density, kinematic viscosity, and flash point, but a lower gross heating value, when compared to the premium diesel. The B01 engine produced higher CO formation and the diesel-fuelled engine produced higher CO than the B02 and B03 did for engine speeds higher than 1400 rpm. Most of the FAME fuels produced higher CO₂ than the diesel fuel did. The FAME fuels emitted higher NO_x and PM, but lower SO₂, than the diesel fuel. C_nH_2n+2, diphenyl sulfone (C₁₂H₁₀O₂S), and diethyl phthalate (C₁₂H₁₄O₄) can be selected as the character index for the combustion of FAME.     

Self‐Aggregation of Catanionic Surface Active Ionic Liquids in Aqueous Solutions

The self‐aggregation behavior of catanionic surface active ionic liquids (SAIL), 1‐alkyl‐3‐methylimidazolium alkyl sulfates, [C₄mim][C₁₆SO₄] and [C₆mim][C₁₄SO₄], in aqueous solutions was explored by several techniques. These results were analyzed together with the concerning data of [C₈mim][C₁₂SO₄] reported previously. The feature of these SAIL is that the total carbon number of the hydrophobic chains is kept constant, while only the length of the two hydrocarbon chains varies. Because of the different intermolecular and intramolecular interactions, the hydrophobic interaction of asymmetrical SAIL is enhanced, which explains the minimal CMC value of [C₄mim][C₁₆SO₄]. Thermal motion of hydrocarbon chains at the air–water interface leads to higher A_min and lower Γ_max values with the increasing asymmetry of two hydrophobic chains. The conductivity measurements reveal that the micellization process is spontaneous and entropy‐driven in the studied temperature range. This work indicates that the symmetry of alkyl chains can influence the aggregation behavior of [C_nmim][C_mSO₄] in aqueous solutions.     

Enhanced catalytic performance over Fe2O3-doped Pt/SO42 −/ZrO2 in n-heptane hydroisomerization

A series of Fe₂O₃-doped (1–5%) Pt/SO₄^2 −/ZrO₂ were prepared by a co-precipitation method. The incorporation of small amounts of Fe₂O₃ into Pt/SO₄^2 −/ZrO₂ results in an enhanced Brønsted acidity in the presence of H₂, which makes the Fe₂O₃-doped catalysts much more active than the undoped one for n-heptane hydroisomerization. A maximal yield of C₇ isomers appears at 3.5% Fe₂O₃.     

Structures and pyroelectric properties for [111]-oriented Mn-doped rhombohedral 0.36PIN-0.36PMN-0.28PT crystal

The crystal structures, pyroelectric properties, and thermal stability of [111]-oriented 0.5 mol% Mn-doped 0.36Pb(In_1/2Nb_1/2)O₃-0.36Pb(Mg_1/3Nb_2/3)O₃-0.28PbTiO₃ (Mn-0.36PIN-0.36PMN-0.28PT) ternary single crystal were investigated. The temperature dependence of the Raman spectra and dielectric properties revealed that the crystal exhibited a rhombohedral (R) structure at room temperature, and ferroelectric R → tetragonal (T) and ferroelectric T to paraelectric cubic (C) phase transitions at 130 and 175°C respectively. The single crystal had a high remnant polarization of P_r = 38 μC cm^–2 and coercive field of E_C = 12 kV cm^–1 at room temperature and a frequency of f = 100 Hz. The values of P_r and E_C decreased with increasing temperature, exhibiting anomalies near their phase-transition temperatures, which coincided with changes in the Raman spectra and dielectric properties. Furthermore, at 25°C and f = 100 Hz, the single crystal had high pyroelectric coefficients of p = 8.7 × 10⁻⁴ C m⁻² K⁻¹, figures of merit for the current responsivity of F_i = 3.5 × 10⁻¹⁰ m V⁻¹, the voltage responsivity of F_v = 0.08 m² C⁻¹, and the detectivity of F_d = 30.1 × 10⁻⁵ Pa^−1/2. These values were weakly dependent on temperature below 120°C. In addition, the room-temperature pyroelectric coefficients of the ternary single crystal maintain over 83% of the original value at thermal annealing temperatures below 120°C. These outstanding pyroelectric properties, together with high thermal stability, indicate that [111]-oriented rhombohedral Mn-0.36PIN-0.36PMN-0.28PT ternary single crystal is a new potential candidate for infrared detection applications.     

Promoting and inhibiting effect of SO2 on propane oxidation over Pt/Al2O3

SO₂ adsorption, SO₂ oxidation and oxidation of propane with oxygen in the absence and the respective presence of SO₂ in the feed gas were studied over unsulfated and sulfated 1% Pt/γ-Al₂O₃.Results showed that the promoting effect of SO₂ in the reaction flux on C₃H₈ oxidation over 1% Pt/γ-Al₂O₃ depends on the presulfating temperature. Catalytic activity measurements and FTIR absorption spectra showed that during propane oxidation, Pt/support interfacial adsorbed species were formed at temperatures 25–300 °C, inhibiting C₃H₈ oxidation. However, at higher temperatures these Pt/support interfacial adsorbed species were oxidized, leading to Pt/support interfacial sulfate species, which strongly promote propane oxidation.     

Catalytic activity of supported metal particles for sulfuric acid decomposition reaction

Production of hydrogen by splitting of water in the thermochemical sulfur-based cycles that employs the catalytic decomposition of sulfuric acid into SO₂ and O₂ is of considerable interest. However, all of the known catalytic systems studied to date that consist of metal particles on oxide substrates deactivate with time on stream. To develop an understanding of the factors that are responsible for catalyst activity, we investigate the fresh activity of several platinum group metals (PGM) catalysts, including Pd, Pt, Rh, Ir, and Ru supported on titania at 850 °C and perform an extensive theoretical study (density-functional-theory-based first-principles calculations and computer simulations) of the activity of the PGM nanoparticles of different size and shape positioned on TiO₂ (rutile and anatase) and Al₂O₃ (γ- and η-alumina) surfaces. The activity and deactivation of the catalytic systems are defined by (i) the energy barrier for the detachment of O atoms from the SO_n (n = 1, 2, 3) species, and (ii) the removal rate of the products of the sulfuric acid decomposition (atomic O, S, and the SO_n species) from metal nanoparticles. We show that these two nanoscale features collectively result in the observed experimental behavior. The removal rate of the reaction products is always lower than the SO_n decomposition rates. The relation between these two rates explains why the “softer” PGM nanoparticles (Pd and Pt) exhibit the highest initial catalytic activity.     

Catalytic oxidation of hydrocarbons over Co3O4 catalyst prepared by CVD

The total oxidation of C₂H₂, C₃H₆, C₃H₈, n-C₄H₈, n-C₄H₁₀ and i-C₄H₁₀ was studied in a monolithic flow reactor under temperature-programmed mode and highly diluted conditions. The non-catalytic combustion of the investigated hydrocarbons leads to a substantial formation of CO and traces of methane at intermediate temperatures. This drawback was suppressed upon the deposition of a thin layer of Co₃O₄ on the monolith and all investigated hydrocarbons tend to light off at 250–290 °C. The apparent activation energy was found to exhibit a linear correlation with the C–H bond dissociation energy, indicating that the C–H activation is still the rate-limiting step.     

Micellization of Anionic Sulfonate Gemini Surfactants and Their Interactions With Anionic Polyacrylamide

Anionic sulfonate gemini surfactants 8‐s‐8(SO₃)₂ and 12‐s‐12(SO₃)₂ (s = 3, 6) were synthesized, and their micellization in aqueous solution at 25.0 °C and pH 9 was investigated. The results show that the critical micelle concentrations (CMC) of 8‐s‐8(SO₃)₂ are more than 2 orders of magnitude larger than those of 12‐s‐12(SO₃)₂, but the spacer length has a relatively small impact on the CMC. Moreover, the interactions of n‐s‐n(SO₃)₂ (n = 8, 12; s = 3, 6) with anionic polyacrylamide (PAM) at 25.0 °C and pH 9 were investigated using surface tensiometry, rheolgy, and scanning electron microscopy (SEM). The results indicate that the surface tension and rheological properties of PAM depend on the concentration of n‐s‐n(SO₃)₂. Below the critical aggregation concentration of C₁, surface tension is sharply reduced, the surface tension of n‐s‐n(SO₃)₂/PAM is lower than n‐s‐n(SO₃)₂ alone, but viscosity is almost unchanged with increasing C_{n‐s‐n(SO3)2}. Above C₁, surface tension reduces very slowly until the saturated concentration of C₂ is reached. Above C₂, surface tension rapidly reduces until C_M is attained, suggesting free n‐s‐n(SO₃)₂ micelles begin to form. In the region of C₁–C_M, the viscosity significantly increases. Above C_M, surface tension is basically unchanged and these curves coincide with those of the single surfactant system. Moreover, the viscosity is almost constant. The SEM images indicate that fibrous aggregates are formed below C₁, then transformed into multilayer fibrous aggregates above C₁, and further into fiber‐braided‐structured and spider‐web‐structured aggregates above C_M. The variation of viscosity is closely associated with the transformation of aggregates.     

Reactivity of aluminum sulfate and silica in molten alkali-metal sulfates in order to prepare mullite

With the aim of preparing mullite, reactions between aluminum sulfate and silica in appropriate proportions and molten sulfate media M₂SO₄ (M=Na and/or K) were performed at different temperatures. The powders obtained were characterized by XRD, FT-IR, SEM and TEM. The reactivity was the same in Na₂SO₄ and (K,Na)₂SO₄ media. The best results in terms of yield (98.3%) and weight of mullite produced (95%) were obtained in Na₂SO₄ at 950 °C. The mullite phase exhibits an acicular morphology (75×0.75 μm) and a specific surface area close to 20 m²/g. In K₂SO₄ medium, a potassium alumino silicate is formed as well as mullite.     

Synthesis and Surface Activities of Novel Succinic Acid Monofluoroalkyl Sulfonate Surfactants

Two environmentally friendly succinic acid monofluoroalkyl sulfonate surfactants were synthesized from maleic anhydride and polyethylene glycol mono (1H,1H,7H‐dodecafluoroheptyl) ether, i.e. H(CF₂)₆CH₂OCH₂CH₂OCOCH(SO₃Na)CH₂COOH (FEOS‐1) and H(CF₂)₆CH₂(OCH₂CH₂)₃OCOCH(SO₃Na)CH₂COOH (FEOS‐3). The obtained surfactants were characterized by FT‐IR, ¹H NMR, ¹³C NMR and ¹⁹F NMR in detail. The synthesized fluorinated surfactants have a high thermal stability on the basis of thermogravimetric analysis. Their surface properties were examined and the results show that FEOS‐1 and FEOS‐3 surfactants can reduce the surface tension of water to 25.55 mN m^?1 at 10.25 mmol L^?1 and 21.63 mN m^?1 at 8.33 mmol L^?1, respectively; meanwhile, the introduction of oxyethylene groups enhances the hydrophilicity and micellar forming ability and the longer oxyethylene chains the better surface properties. The Krafft points (K_p) of FEOS‐1 and FEOS‐3 were both below 0 °C, which was lower than perfluoro‐n‐heptanesulfonic acid sodium salt (n‐C₇F₁₅SO₃Na, K_p = 56.5 °C) at a similar length of fluorocarbon chains. Comparison studies on two surfactants above and the conventional fluorocarbon surfactants, perfluorooctanoate of ammonium (PFOA) show that the surfactants have comparable properties to PFOA, thus offering an environmentally friendly synthesizing alternatives to PFOA.     

Microporous PDMAEMA‐based stimuli‐responsive hydrogel and its application in drug release

The microporous hydrogels (Pn‐Cm gels) composed of poly(dimethylaminoethyl methacrylate) and carboxymethylchitosan were synthesized in situ radical polymerization by using nano γ‐Fe₂O₃ particles as pore‐agent. The microporous structure formed through eliminating the Fe₂O₃ particles was designed to achieve a faster response rate and better drug loading effect. Comparing to the neat gels, Pn‐Cm gels exhibit deteriorative mechanical properties with the increased pores, while the gels still keep the elastic network structure which could bear some degree of tensile and compression deformation. Meantime, Pn‐Cm gels show similar temperature and pH double responsiveness with same isoelectric point shrink as that of neat gels, the swelling ability decreases slightly, and the deswelling rate increases with the increase of pores. Moreover, the 5‐fluorouracil was used as a target drug to explore the potential of this gel applied as drug‐release system. For Pn‐Cm gels, the more pores and carboxymethyl chitosan inside the gels are beneficial to the drug loading, all gels show a burst release of drug, being followed by a slow and sustained release with different rate. Comprehensively, the Pn‐Cm gels exhibit a better sustained release effect in the simulated stomach condition (pH = 2.1), the related release mechanism could be interpreted by the superposition of Fickian diffusion. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45326.     

On the presence of polytetrahydrofuran in the polyspiro‐phosphazenes [NP(O2C12H8)]n prepared from [NPCl2]n and 2,2′‐dihydroxybiphenyl in THF as solvent

Polydichlorophosphazene [NPCl₂]_n reacts with the diphenol 2,2′‐(HO)C₆H₄‐C₆H₄(OH) in THF in the presence of K₂CO₃ to give the polymers [NP(O₂C₁₂H₈) · x(OC₄H₈)]_n (1) that contain variable ammouts of polytetrahydrofuran (PTHF) with x ranging from 0.05 to 0.8. This PTHF content (x) depends on the method followed to prepare the THF solutions of [NPCl₂]_n used for the reactions with the biphenol and can be made negligibly small, forming these solutions in the presence of K₂CO₃. This reveals the presence in the [NPCl₂]_n of acidic species capable of catalyzing the ring opening polymerization of THF. Polyphosphazene [NP(O₂C₁₂H₈)]_n (2) was prepared completely free of PTHF using dioxane as solvent. A comparison of the thermal behavior and morphological data of the polymers 1, 2, PTHF (5), and mixtures of [NP(O₂C₁₂H₈)]_n + x(OC₄H₈)_m (4) revealed that the products 1 are strongly interacting polymer blends and ruled out the possibility of block copolymers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 568–576, 2000