High temperature polymers. II. High temperature polymers from 4,4′-[sulfonylbis-(p-phenyleneoxy)]dianiline

Novel aromatic diamines have been prepared which contain an ordered sequence distribution of thermally stable, flexible, or rigid units. The synthesis of these materials involves a nucleophilic displacement reaction in aprotic solvent with, for example, the alkali metal salt of p-aminophenol, optionally, the salt of a bisphenol and an activated aromatic halide. Such monomers are useful “building blocks” for various polymeric systems but are of special interest in those which can benefit from the high glass transition temperature imparted by polar or rigid moieties, together with improved impact properties conveyed by either groups. Polyimides and polyamide-imides are examples and display high heat distortion temperatures, good solvent resistance, excellent mechanical properties, high thermal and oxidative stability and depending on diamine structure and molecular weight, thermoplastic characteristics. The synthesis and properties of polyamides, polyimides and polyamide-imides based on 4,4′-[sulfonylbis(p-phenyleneoxy)] dianiline are presented in this paper.     

Phthalocyanine polymers. I. Poly[2,2′-(4,4′,4″-,4‴-metal phthalocyanino)-5,5′-bibenzimidazoles] as new high temperature resistant polymers

A novel class of poly(metal phthalocyanino) benzimidazoles were prepared by the condensation reaction between metal (Cu, Co, and Zn), 4,4′,4″,4?-tetracarboxyphthalocyanine, and 3,3′-diaminobenzidine. The reaction was investigated by melt and solution condensation methods. These polymers showed excellent thermal and thermooxidative stability and are noteworthy for their high char yield (86–90%) at 800°C in an anerobic atmosphere. Elemental analyses, spectra, and TGA studies were used to characterize these materials. Isothermal gravimetric analyses were carried out to determine their long-term thermal stability.     

New high temperature polymers. I. Wholly aromatic ordered copolyamides

Wholly aromatic ordered copolyamides of unusually high thermal stability were prepared by the condensation of aromatic diacid chlorides with symmetrical diamines containing preformed aromatic amide units in an ordered arrangement. The preservation of order in the condensation step was assured by using interfacial or solution polymerization techniques at temperatures below 50°C. Each polymer contains units derived from aminobenzoic acids, arylene diamines, and arylene diacids. By use of para- and meta- phenylene units, eight different polymers are possible; all were prepared. Differential thermal analyses and thermogravimetric analyses showed these polymers to have melting points or decomposition temperatures in a range from 410°C. for the all-meta polymer to 555°C. for the all-para one. Substitution of the internal N-hydrogens of the diamines with methyl groups or phenyl groups leads to additional ordered copolymers. Several were prepared, but their melting points were much lower than those of the parent polymers limiting their usefulness in high temperature applications. Tough pliable films were prepared from all eight unsubstituted polymers, and crystalline fibers with tenacities of ca. 6 g./den. were prepared from three of the polymers. The properties of the fibers were retained to a high degree even when determined at temperatures up to 400°C. Fibers aged at 300°C. for extended periods of time showed remarkable retention of fiber properties.     

High oven temperature — cold on-column injection for the automated CGC analysis of high molecular weight compounds such as triglycerides

Modification of the Carlo-Erba cold on-column injector for (automated) analysis of high molecular compounds at high oven temperature is described. The secondary cooling tube of the cold on-column injector is replaced by a lengthened tube through which a high air flow is directed. The injection site is maintained at 65–70 °C while the oven is at high temperature (? 300 °C). For automated injection, a short deactivated precolumn of 22 to 30 cm × 0.53 mm i.d. is coupled to the analytical column via a butt connector with make-up gas supply. For a triglyceride mixture, automatically injected at 300 °C, the mean % deviation for all peak areas was 1.8% and the mean % deviation for all retention times was 0.09 % for five consecutive runs.     

Poly-Schiff bases. I. Preparation of poly-Schiff bases from 4,4′-diacetyl diphenyl ether (DDE) with various diamines

Thermally stable and semiconducting poly-Schiff bases are synthesized by condensing 4,4′-diacetyl diphenyl ether with o-, m-, and p-phenylene diamines, benzidine, and ethylene diamine under different experimental conditions. These bases are insoluble in common organic solvents. They are characterized by infrared (IR) and viscosity measurements, thermal analysis, and the study of electricel properties at various temperatures. Variation of electrical conductivity σ with temperature followed the empirical relation σ = σ₀e^?E*/kT.     

High resolution mass spectrometry—I. Some substituted δ-lactones

The mass spectra of some δ-lactones substituted in various positions by methyl groups have been studied both by accurate mass measurements at high resulution and by deuterium labelling. The loss of carbon dioxide has been shown to be important only for a mono-substituted lactone. A fragmentation mode common to all the lactones studied is the elimination of the ring oxygen atom, plus the adjacent carbon atom with its substituents, as a neutral carbonyl molecule such as formaldehyde, acetaldehyde or acetone. Deuterium labelling has uncovered the existence of a rearrangement involving hydrogen transfer in an even-electron ion, and a mechanism involving a six-membered transition state is proposed for this. The bond fissions, common to all the lactones, by which the principal ions in the mass spectra arise, are summarised.     

Non‐mutagenic organic pigment intermediates. I. 3,3′‐Dipropoxybenzidine

Crystals of the title compound, C₁₈H₂₄N₂O₂, were grown from ethanol by slow evaporation and the structure has been determined. The mol­ecule resides on a crystallographic inversion center and the bi­phenyl moiety is essentially planar. The structure forms an infinite two‐dimensional array of N—H⋯π(arene) interactions parallel to the (101) direction.     

Decomposition of the t-butoxy radical — I. Studies over the temperature range 402–443 K

By allowing the t-butoxy radical to decompose in the presence of nitric oxide, it has been possible to determine rate constants for decomposition by the measurements of the relative rates (2) and (3) Process (3) is clearly pressure dependent. The value of k₃(∞) has been determined in the presence of several inert gases (CF₄, SF₆, N₂, and Ar) and a value of k₃ interpolated for atmospheric conditions. The results may be compared with those for other relevant alkoxy radicals at room temperature. Extrapolated values for k₃ in the presence of CF₄ lead to the result      

Block polymers from isocyanate-terminated intermediates. II. Preparation of butadiene–ϵ-caprolactam and styrene–ϵ-caprolactam block polymers

Polystyrene–nylon 6 and polybutadiene–nylon 6 block copolymers have been prepared from isocyanate-terminated prepolymers. From extraction and fractionation data the products obtained were found to be mixtures of both homopolymers and pure block copolymer. The polybutadiene–nylon 6 copolymers are extremely pliable at ambient temperatures even at high ?-caprolactam contents (70–80 wt-%). This is true even though these copolymers show a crystalline melting point at 213°C similar to poly-?-caprolactam. Presumably this unusual behavior occurs because of the nature of the synthesis which renders the butadiene portion of these copolymers the continuous phase. Plasticity measurements indicate that pliability is dependent on the molecular weight of the block poly-?-caprolactam.     

High temperature polymers. III. Diphenyl sulfone-based polyamide-imides

High temperature thermoplastic polyamide-imides were prepared from a new series of aromatic diamines containing the diphenylsulfone unit and alternatively, oxydiphenyl and diphenylisopropylidene units. The polymers were prepared in their completely imidized form by using a facile in situ chemical imidization reaction which offers several advantages over the conventional thermal imidization process. The sulfone-based polyamide-imides exhibited an excellent combination of moldability, thermal stability, mechanical properties and solvent resistance. Analysis of the properties of these polymers in terms of structural variations permits a useful correlation of the effect of various structural units on performance. The polar diphenyl sulfone and amide-imide units increase the glass transition temperature and improve solvent resistance while the oxydiphenyl and diphenylisopropylidene units improve thermoplasticity. Sulfone ether diamine polyamide-imide (VI) offers the best combination of high temperature performance and moldability.     

Chelate polymers. III. New polyazomethines of 5,5′‐methylene‐bissalicylaldehyde with siloxane diamines and their divalent metal complexes

Novel polymeric azomethines of 5,5′‐methylene‐bissalicylaldehyde with two siloxane diamines {H₂N(CH₂)₃(CH₃)₂SiO[(CH₃)₂SiO]_mSi(CH₃)₂(CH₂)₃NH₂, where m = 0 or 6.5} were obtained. Their structures were confirmed by elemental and spectral [IR, ultraviolet–visible (UV–vis), and ¹H NMR] analysis. The obtained polyazomethines were converted into the chelates of some divalent metals (copper, cobalt, and nickel). The resulting complexes were characterized by electronic and IR spectral measurements, elemental analysis, and thermal studies. From IR and UV–vis studies, the phenolic oxygen and imine nitrogen of the ligand were found to be the coordination sites. The thermogravimetric data indicated that the chelates were less stable than the corresponding ligands and that the thermostability depended on the siloxane segment length and the nature of the metal. Both the macromolecular ligands and the parts of the resultant chelates were soluble in common organic solvents, such as CHCl₃, CH₂Cl₂, dimethylformamide, and dimethyl sulfoxide. The surface compositions of the ligands and some chelates were examined by X‐ray photoelectron spectroscopy. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3169–3179, 2003     

Degradable dendritic polymers — A template for functional pores and nanocavities-

Degradable dendrimers are prepared as a template to create utrasmall cells when they get embedded in a polymer resin and to obtain well-defined cavities with particular chemical groups at their walls if the endgroups remain attached to the matrix. In a first approach cascade: (13-oxa-1-methylsilaundecenylidene): undecene was synthesised by the polyaddition reaction of methyl-di-undecenoxysilane as basic repeat unit. A multimodal weight distribution was found which appeared to be selfcontrolled to a limited molecular weight. Degradation was done with dry methanol and methanol with aqueous hydrochloric acid. In the case of dry methanol, the degradation products yielded only low molecular weight compounds while siloxane bonds were formed in the case the degradation was performed with methanol and aqueous hydrochloric acid. In order to create films with nanocavities, the degradable dendritic macromolecules were embedded in a methacrylate resin. Hole formation was illustrated by transmission electron microscopy for the case of 0.5 wt.-%, 5 wt.-% and 30 wt.-% of dendrimer content. However, aggregation of the dendritic molecules during the curing of the methacrylate resin could not be avoided. In order to suppress aggregation, cascade: (1-methylsilapropylidene): propene with methacrylate endgroups have been prepared which can be covalently linked to the embedding resin molecules. In a first approach the compatibility with the methacrylate resin was indicated by the optical transparency, while microscopy techniques were not capable to resolve the fine structure.     

The sulfonation of crosslinked poly(ether ether ketone)—Diffusion‐controlled kinetics

The effect of crosslinks introduced by ion irradiation with 11.7 MeV proton and 30 MeV helium ions on the reactivity of poly(ether‐ether‐ketone) (PEEK) to sulfonation have been investigated following the kinetics of the reaction at room temperature. Concentrated sulfuric acid was used as a swelling and sulfonating agent and the reaction was followed by changes in the FTIR spectrum. The rate of reaction decreased with the degree of crosslinking and the progress with time was consistent with diffusion control of the sulfuric acid into the crosslinked matrix. The results were consistent with the efficiency of the ions in crosslinking PEEK and in particular with the differences in their linear energy transfer (LET). © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 775–783, 2009     

New high temperature polymers. VI. Ordered heterocycle copolymers

A new class of linear, thermostable polymers is reported. The compositions are ordered heterocycle copolymers in which two different heterocycles alternate regularly along the polymer chain. Examples of combinations studied are: oxadiazole–benzimidazole, oxadiazole–pyromellitimide, and thiazole–pyromellitimide. The heterocycle copolymers, or alternatively, the corresponding precursor polymers, were prepared by condensing preformed di-or tetrafunctional blocks which contain one type of heterocycle with a second di- or tetrafunctional monomer under such conditions that no rearrangement of bonds occurred. The polymers are characterized in general by neither melting nor decomposing below 500°C. when heated in an inert atmosphere at a rate of about 10°C./min. Some of the copolymers are readily soluble in organic solvents; many, however, are soluble only in solvents such as concentrated sulfuric acid. In the case of the more intractable polymers, soluble precursor polymers can usually be prepared. In such precursor polymers only one of the heterocycles is preformed; the second heterocycle is formed by post-treatment after the polymer has been fabricated into an end product. All of the polymers yielded self-supporting films, some having very high strength; films of several of the polymers were hot-drawable. Drawn film of an ordered oxadiazoleimide copolymer was shown to be well oriented and moderately crystalline.     

Bisorthoesters as polymer intermediates. I. Synthesis of bisorthoesters

Derivatives of three types of bisorthoesters, hexaalkyl orthoisophthalates, hexaalkyl orthoterephthalates, and hexaethyl orthooxalate, were synthesized. The orthoesters of isophthalic and terephthalic acid were prepared from α, α, α, α′, α′, α′ -hexachloro-m-xylene or hexachloro-p-xylene, respectively. It was found more advantageous to prepare initially the hexamethyl orthoesters by reacting the hexachloro compounds with sodium methoxide in methanol either at the boiling point of methanol or under pressure at temperatures up to 200°C. Transesterification with higher alcohols, for example, ethanol or propanol, with the aid of molecular sieves gave the higher bisorthoesters in high yield and high purity. Attempts to synthesize orthoisophthalates and orthoterephthalates of higher alcohols directly from the hexachloroxylenes and alkoxides of higher alcohols gave only low yields of impure products. The Pinner synthesis of the bisorthoesters from the corresponding dinitriles was also ineffective. The ease of purification of hexa-n-propyl orthoisophthalate and orthoterephthalate makes these orthoesters the favored candidates for use in polymer syntheses. Hexaethyl orthooxalate was prepared in a three-step synthesis from triethyl orthoformate by a convenient, but low yield reaction. All bisorthoesters were purified to give compounds which were monomer grade materials free of normal esters.     

Solid state NMR — A tool for studying molecular motion in polymers

After an introduction describing the development of ¹H, ²H, and ¹³C solid state NMR two sections on ¹³C and ²H NMR, respectively, outline the physical background as related with molecular motion. Some representative examples demonstrate the potential of recent NMR techniques in polymer dynamics studies.     

γ-Radiolysis of ketone polymers. I. Studies of symmetrical aliphatic ketones as model compounds

γ-Radiolysis of model ketones of the general structure R(C?O)R, neat and in hydrocarbon solution, show that the radio-chemical degradation of these aliphatic ketones can be explained by mechanisms analogous to those generally accepted for the photochemical decompositions of the same compounds. The G (type I) and G (type II) yields are found to decrease with increasing total chain length of the ketone as monitored by the products (R? H) and (CH₃CO? R), respectively. Differences in the relative yields of type I and II products are attributed to the higher incident energies involved in γ-radiolysis as compared to ultraviolet photolysis. Evidence is presented for energy transfer from paraffinic solvents to aliphatic ketonic solutes. Solid- and condensed-phase studies show the importance of rotational and diffusional mobility to the yields of the type II and I processes, respectively.     

High resolution mass spectrometry.—II Some substituted benzothiazoles

The mass spectra of nineteen substituted benzothiazoles have been recorded and the identity of the various ions in the mass spectra has been established by high resulution (accurate) mass measurement. Deuterium labelling has been used to elucidate the fragmentation processes of these compounds. The parent compound of the series, benzothiazole, exhibits the loss of hydrogen cyanide and carbon monosulphide from the parent ion as the most important decomposition pathways. The hydrogen atom concerned in the loss of hydrogen cyanide is shown to originate from the 2-position of benzothiazole, while in 2-substituted benzothiazoles, different mechanisms are apparent for the loss of hydrogen cyanide, and these are clarified by deuterium labelling. Some substituted benzothiazoles can lose sulphur from their molecular ions, a process which does not occur in benzothiazole itself. The substituted benzothiazoles undergo many other types of fragmentations, in some cases retaining the substituent, and in other cases losing it prior to collapse of the thiazole ring.