Synthesis, characterization and properties of novel thermally stable poly(urethane-oxazolidone) elastomers

Oxazolidone-incorporated polyurethane elastomers based on hydroxyl terminated polycaprolactone, were synthesized and characterized. Reaction of epoxy-terminated polyurethane with isocyanate librated from a blocked polyisocyanate was the strategy followed. The reaction condition was optimized through preparation of model oxazolidones. Epoxy-terminated polyurethanes were prepared from reaction of glycidol with NCO-terminated polyurethane prepolymers and curing agent was synthesized from the reaction of trimethylol propane, toluene diisocyanate and N-methyl-aniline. Incorporation of heterocyclic oxazolidone groups into the polyurethane backbone caused improvements in thermal and mechanical properties. Investigation of structure-property relationship for prepared elastomers showed that the main determining factors for observed properties were crosslink density, crystallinity and content of oxazolidone rings.     

Synthesis and characterization of a novel high thermally stable energy compound： 1-（1-Adamantylamino）-2,4,6-trinitrobenzene

1-（1-Adamantylamino）-2,4,6-trinitrobenzene （1） as a potential energy material has been synthesized in excellent yield and characterized by FT-IR, 1H NMR and single crystallographic methods, and is thermally stable, decomposed in the range of 215- 72℃.     

Synthesis and ion-exchange properties of thermally stable stannic selenite

Stannic selenites have been synthesized under a variety of conditions. The most stable sample is prepared by mixing 0-0.5M solutions of stannic chloride and sodium selenite in the ratio of 1:1 at pH 1. It is a bifunctional amorphous material. A tentative structure has been proposed on the basis of chemical composition, pH titrations, infrared and thermogravimetric analyses. Its ion-exchange capacity is 0.75 and 0.73 meq g after drying at 50 degrees and 500 degrees respectively. Its analytical importance has been established by the following quantitative separations: Cu(2+) from Ni(2+), Co(2+), Fe(3+), Ga(3+) and In(3+), Fe(3+) from Pb(2+) and Sc(3+), and Sc(3+) from VO(2+).     

Synthesis and properties of thermally stable polyimides bearing pendent fluorene moieties

A new diamine monomer containing fluorene unit, 3,5‐diamino‐N‐(9H‐fluoren‐2‐yl)benzamide was successfully synthesized via the condensation of 2‐aminofluorene and 3,5‐dinitrobenzoyl chloride and subsequent reduction of the dinitro compound. A series of novel aromatic polyimides having pendent fluorenamide moieties were prepared from the reaction of the diamine monomer and various tetracarboxylic dianhydrides by a conventional two‐step polymerization process. The polyimides were obtained in quantitative yields with inherent viscosities of 0.33–0.44 dl/g. The resulting polymers dissolved in N‐methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide, N,N‐dimethylformamide, and dimethyl sulfoxide. The glass transition temperature of these polymers was in the range of 261–289°C. They were fairly stable up to a temperature around 450°C and lost 10% weight in the range of 498–556°C in nitrogen. The UV–vis absorption spectra showed that all of the polymers had absorption maxima around 320 nm. Cyclic voltammograms of the polyimides revealed an oxidation wave with a peak around 1.3 V. Copyright © 2014 John Wiley & Sons, Ltd.     

Novel thermally stable poly(thiourea-amide-imide)s bearing CS moieties and pyridine units in the backbone: Synthesis and properties

Novel thermally stable and organosoluble poly(thiourea-amide-imide)s (PTAIs) were synthesized through the condensation of various diamines with a new kind of aromatic diacid chloride monomer containing pyridine units, 2-(3-(2-(3-(chlorocarbonyl)pyridin-2-yl)-1,3-dioxoisoindoline-5-carbonyl) thioureido) nicotinoyl chloride, CPDITNC. Spectroscopic and elemental analyses were carried out for the structure elucidation of synthesized monomers. Accordingly, the ensuing PTAIs were characterized by FTIR, ¹H and ¹³C NMR techniques along with crystallinity, organosolubility, inherent viscosity and GPC measurements. Consequently, polymers bearing phenyl thiourea and pyridine moieties in the backbone exhibited good organosolubility in a variety of highly polar solvents such as DMAc, DMF, DMSO and NMP. PTAIs encompassed η_inh of 1.24-1.46 dL/g and two of the polymers showed crystalline behavior. Moreover, GPC measurements of polymers revealed M_w around 33,000-50,000. Thermal stability of these polymers was ascertained via 10% weight loss temperatures in the range of 548-562 °C (inert atmosphere). Ultimately, these polymers own high glass-transition temperatures about 264-270 °C.     

Synthesis and characterization of thermally stable and flame retardant poly (benzoxazine-co-urethane) matrices

Abstract

The flame-retardant behavior of organic polymers is considered as very important criteria to utilize them in the form of coatings, encapsulants, sealants, and matrices for high performance industrial applications. A new type of poly (benzoxazine-co-urethane) (PBZ-co-PU) matrices have been developed using dimethylol benzoxazine monomers (BZM and BZE) and tris(p-isocyanatophenyl)thiophosphate (Desmodur) through A₂?+?B₃ approach followed by thermal curing. The molecular structure of developed PBZ-co-PU was confirmed by FT-IR spectra and their thermal stability and flame retardant behavior were studied by standard methods. Data obtained from TGA and DSC, indicate that the PBZ-co-PU possesses higher Tg, better thermal stability and LOI than those of neat PBZ. Further, it was also observed that among the two matrix systems (PBZ-co-PU-1 and PBZ-co-PU-2) studied, the PBZ-co-PU-1 based system exhibited higher T_g, thermal stability and flame retardant behavior than those of PBZ-co-PU-2.     

Synthesis and properties of highly thermally stable ultrathin films of fluorine-containing hyperbranched polybenzoxazoles

In this paper, we aimed to develop ultrathin films of hyperbranched polybenzoxazole with a thickness in the range between 1 and 100 nm. They are expected to have great potential for various applications as functional materials due to their high thermal stability, good chemical resistance and mechanical strength. The synthesis of various hyperbranched poly(o-hydroxyamide)s as precursors of polybenzoxazole was examined by the polycondensation of 2,2-bis(3-amino-4-hydroxyphenyl)propane (AHP) and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (AHFP) with 1,3,5-benzenetricarbonyl trichloride (BCC), yielding the corresponding hyperbranched poly(o-hydroxyamide), poly(AHFP_m-co-AHP_n-co-BCC_2.0), with M_n in the range between 12,870 and 22,210 in satisfactory yields. Poly(AHFP_3.0-co-BCC_2.0), poly(AHFP_2.25-co-AHP_0.75-co-BCC_2.0), and poly(AHFP_1.50-co-AHP_1.50-co-BCC_2.0) showed good solubility and film-forming ability, and ultrathin films 8.9–88.6 nm thick were prepared on silicon wafers. Heating of the ultrathin films of poly(AHFP_m-co-AHP_n-co-BCC_2.0) on a hot plate at 350 °C for 1 h afforded the corresponding ultrathin films of hyperbranched polybenzoxazole, poly(AHFP_m-cyclo-AHP_n-cyclo-BCC_2.0), with a thickness of 5.3–82.4 nm. Double-layer thin films consisting of resist materials on top of hyperbranched polybenzoxazole were also prepared.     

Synthesis of thermally stable aromatic poly(spiroorthocarbonate)s having a Cardo or bent structure

Novel poly(spiroorthocarbonate)s [poly(SOC)]s having a Cardo or bent structure were synthesized by polycondensation of several bis‐catechols having fluorene (BCFL), spirobisindane (BCSPI), or spirobischromane (BCSPC) in the structure with 2,2,6,6‐tetrachlorobenzo[1,2‐d:4,5‐d’]bis[1,3]dioxole (4ClBD). Synthesis of poly(SOC)s was confirmed by NMR and IR spectrometry. The poly(SOC)s obtained from BCFL or BCSPC were soluble in common organic solvents. The glass transition temperature of the poly(SOC)s was not detected by differential scanning calorimetry (DSC) in the range of 50–300 °C. The 10 wt % decomposition temperature of the poly(SOC)s was found to be above 400 °C. These results indicated the high thermal stability of the poly(SOC)s. Soluble poly(SOC)s could be possessed to form a film on a glass plate by the spin coat method. The obtained polymer films were 0.2 μm in thickness with 95% light transmission in the optical wavelength range. These results suggested that the Cardo or bent structure may block the packing of the main‐chain of the structure, which improves the solubility of the polymers, increases transparency, and enhances the thermal stability of SOCs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1409‐1416     

Synthesis and characterization of thermally stable sulfonated polybenzimidazoles

A series of sulfonated polybenzimidazoles (sPBI-IS) with controlled sulfonation degrees (SDs) were synthesized from various stoichiometric ratio mixtures of 5-sulfoisophthalic acid monosodium salt (SIPN), 4,4′-sulfonyldibenzoic acid and 3,3′-diaminobenzidine by solution copolycondensation in poly(phosphoric acid). The resulting sulfonated polymers were characterized by means of FTIR, ¹H NMR and GPC, in addition to TGA and DMA. The number-average molecular weights (M_n) of the sPBI-IS are in the range of 45,500-64,000, and the polydispersity indices (M_w/M_n) vary from 1.9 to 2.4. The synthesized sPBI-IS samples present good solubilities in polar aprotic solvents and they are easy to form the transparent, flexible and tough films by solution casting. These polymer membranes show excellent thermal stabilities and dynamic mechanical properties. The thermal stability of the sodium form sPBI-IS remarkably increases with increasing SD. However, the acidic form sPBI-IS presents less thermal stability than the non-sulfonated sample (sPBI-IS0). The onset decomposition temperature (T_d) and the glass-transition temperature (T_g) of the acidic form sPBI-IS70 are 439 °C and 196 °C, respectively. The sulfonated membranes show higher storage moduli and loss moduli than sPBI-IS0. The resulting sPBI-IS membranes with high hygroscopicity show potential application as the high temperature proton exchange membrane in fuel cell.     

Synthesis and ion-exchange properties of cerium(IV) molybdate

Cerium(IV) molybdate, prepared under the optimum conditions of concentration, acidity etc., shows exchange capacity of 0.96 meq per g of exchanger. The sorption of a large number of metal ions has been investigated and the compound shows promising behaviour as cation exchanger. Numerous separations of analytical and radiochemical interest have been performed on the columns of this exchanger with great efficiency.     

Synthesis and structure of new water-soluble and stable tantalum compound: ammonium tetralactatodiperoxo-mu-oxo-ditantalate(V)

The stable water-soluble tantalum complex with lactic acid (ammonium tetralactatodiperoxo-mu-oxo-ditantalate(V)), (NH4)4[Ta2(C3H4O3)4(O2)2O].3H2O, was prepared in the crystalline form. According to the single-crystal X-ray diffraction data, this compound forms a monoclinic cell with a = 13.85(2) A, b = 9.06(1) A, c = 12.32(2) A, and beta = 116.30 degrees , space group C2 (No. 2), and has Z = 2 molecules per unit cell. The solid-state 13C NMR data and low flack parameter are consistent with the determined structure. Appearance of the same vibration modes in Raman and IR spectra supports the choice of the space group without inversion symmetry. The solution of the tantalum complex was successfully applied for the synthesis of two photocatalytic materials, NaTaO3 and Sr2Ta2O7.     

Synthesis and properties of stable aromatic bis(nitrile oxides)

A number of stable bis(nitrile oxides) based on dimesitylmethane and didurylmethane and their analogs in which two aromatic rings are joined by various bridging groups were synthesized. The thermal isomerization of the bis(nitrile oxides) to diisocyanates and the relative reactivities of the bis(nitrile oxides) in 1,3-dipolar cycloaddition to styrene were studied.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1398–1403, June, 1991.     

Synthesis and properties of thermally stable and optically active novel wholly aromatic polyesters containing a chiral pendent group

5-(2-Phthalimidyl-3-methyl butanoylamino)isophthalic acid (5), as a novel diacid monomer containing phthalimide and flexible chiral groups, was prepared by the reaction of 2-phthalimidyl-3-methyl butyric acid chloride (4) with 5-aminoisophthalic acid (5AIPA) in dry N,N-dimethylacetamide (DMAc). A series of novel polyesters (PE)s containing phthalimide group was prepared by the reaction of diacid monomer 5 with several aromatic diols via direct polyesterification with the tosyl chloride/pyridine/dimethylformamide (DMF) system as a condensing agent. The resulting new polymers were obtained in good yields with inherent viscosities ranging between 0.37 and 0.61 dL g⁻¹ and were characterized with FT-IR, ¹H NMR, elemental and thermogravimetric analysis techniques. These polymers are readily soluble in amide type solvents such as DMAc, DMF, 1-methyl-2-pyrrolidone, hexamethyl triaminophosphine, dimethyl sulfoxide and protic solvents such as sulfuric acid. Thermogravimetric analysis showed that the 10% weight loss temperature in a nitrogen atmosphere was more than 345 °C, which indicates that the resulting PEs have a good thermal stability as well as excellent solubility.