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The synthesis, processing, and engineering of halogen-free, low heat release, fire-resistant materials present important challenges in polymer materials chemistry. One approach to this problem involves the use of polymers that char upon decomposition, reducing the evolution of flammable gas and acting as an insulating layer. Demonstrated here is the synthesis of novel char-forming polyarylates prepared by interfacial polycondensation of 4,4‘-bishydroxydeoxybenzoin (BHDB) and isophthaloyl chloride. A variety of copolyarylates containing BHDB, bisphenol A (BPA), and isophthaloyl chloride were prepared and shown to exhibit superior fire resistance to many polymers in the low flammability category. A char yield of 42% and heat release capacity of 62 J/(g K) were measured for the BHDB-containing polyarylate, while polyarylates containing both BHDB and BPA combined desirable fire-resistant properties with appreciable polymer solubility and processability.

The synthesis, processing, and engineering of halogen-free, low heat release, fire-resistant materials present important challenges in polymer materials chemistry. One approach to this problem involves the use of polymers that char upon decomposition, reducing the evolution of flammable gas and acting as an insulating layer. Demonstrated here is the synthesis of novel char-forming polyarylates prepared by interfacial polycondensation of 4,4‘-bishydroxydeoxybenzoin (BHDB) and isophthaloyl chloride. A variety of copolyarylates containing BHDB, bisphenol A (BPA), and isophthaloyl chloride were prepared and shown to exhibit superior fire resistance to many polymers in the low flammability category. A char yield of 42% and heat release capacity of 62 J/(g K) were measured for the BHDB-containing polyarylate, while polyarylates containing both BHDB and BPA combined desirable fire-resistant properties with appreciable polymer solubility and processability.

The detailed mesophasic characterization of main chain liquid crystalline polyurethanes containing biphenyl mesogen, which were synthesized by the novel AB‐type self‐polycondensation approach, was carried out by using Differential Scanning Calorimetry (DSC), Polarized Optical Microscopy (POM), variable temperature X‐ray Diffraction (XRD), and Fourier Transform Infrared (FT‐IR) spectroscopic studies. The type of mesophase present in these polymers was identified to be the smectic A phase by POM and XRD studies. The smectic layer thickness was found to increase as the length of the spacer increased. The effect of temperature on the hydrogen bonding was analyzed by FT‐IR studies. The curve‐fitting analysis of the NH stretching and C&dbond;O stretching modes of vibrations indicated a gradual decrease in hydrogen bonding during the transition from the crystalline state to the mesophase. The mesophase to isotropic liquid transition was then accompanied by the complete disappearance of the hydrogen bonding. The biphenyl bands also showed changes during phase transitions due to the coupling of biphenyl vibration modes with the urethane linkage attached to it. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1903–1912, 2005

A homologous series of main-chain thermotropic liquid-crystalline polyesters containing rigid biphenyl mesogen and flexible methylene spacers were synthesized with the AB-type self-polycondensation approach. The polyesters were characterized with ¹H NMR, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, polarized light optical microscopy, and X-ray diffraction. These polyesters, containing trimethylene spacers on the acid side and various spacers on the alcohol side of the biphenyl mesogen, showed an odd–even effect in the transition temperatures and mesophase type. The even members showed higher transition temperatures than the odd ones. A normal smectic mesophase was observed for the even members, whereas the odd-membered counterparts exhibited a tilted smectic mesophase. To study the effect of connectivity, the mesophase characteristics of these polyesters were compared with those of the isomeric AB-type polyesters without any methylene spacer on the acid side of the biphenyl moiety. The mesophase characteristics were insensitive to whether the mesogen was connected to a carboxyl unit or a methylene unit. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2734–2746, 2004

Aqueous two-phase extraction (ATPE) is basically a liquid–liquid extraction technique employing two aqueous phases comprising either two polymers or a polymer and a salt. In addition to the other advantages it offers, ATPE is gaining increasing popularity as an environmentally benign technique because (1) it does not employ volatile organic compounds as solvents, (2) it involves phase-forming polymers that rely on the structuring properties of liquid water not only for the formation of phase systems but also for solubilizing the otherwise relatively insoluble hydrophobic solutes, (3) it exploits the remarkable properties of polymers such as polyethylene glycols, polyvinyl pyrrolidone (PVP) etc. and (4) it makes use of phase-forming components which could be recovered and recycled to a limited degree. In some modified form, ATPE is finding application in environmental remediation. ATPE is discussed by considering case studies involving extraction of enzymes for waste treatment and recovery of valuable by-products from waste, extraction of useful components of plant origin and extraction of natural colours. The scope of ATPE in the context of pollution prevention or application for environmental remediation is discussed. Advantages/limitations of ATPE are also discussed. Barriers to a widespread industrial application of ATPE are examined and possible solutions suggested.

Casein was treated with triethanolamine and made into films. The mechanical properties of the alkali treated casein films were studied under uniaxial and biaxial stress conditions. A reduction in longitudinal stress and elongation at break was observed with the simultaneous application of lateral stress.

Dodecamethylcyclohexaphosphazene N6P6Me12, 1, forms 1:1 complexes with palladium(II) chloride, 2, and platinum(II) chloride, 3. Their 31P, 1H, and 13C nmr spectra show them to be rigid molecules in solution, with an approximate plane of symmetry. Crystals of 2are orthorhombic, a = 17.4030(3), b = 15.4897(5), c = 10.7417(2) Å, Z = 4, space group P21212. The structure was determined from diffractometer X-ray data and refined by full-matrix least-squares methods to R = 0.031 for 3545 reflections with I ≥ 3σ(I). The metal atom has square planar coordination, and forms 6- and 10-membered chelate rings with the phosphazene ligand. The mean P—N bond length is 1.609 Å; the variation of bond lengths within the ring is consistent with model calculations of changes in bond order arising from the localization of bonding electrons.

Crystals of the title compound are orthorhombic, a = 7.387(1), b = 8.502(2), c = 14.662(2) Å, Z = 4, space group Pnma. The structure was solved by direct methods and refined by least-squares procedures to a final Rof 0.058, Rw = 0.097 for the 530 reflections with I > 3σ(I). The P3N3ring is slightly but significantly non-planar with a crystallographically-imposed mirror plane normal to the ring, and the PN bond lengths in order from the PMe2group are 1.601(7), 1.552(7), and 1.560(6) Å. The ring angles are 114.0(4)°, (PMe2); 120.0(4)°, PF2; 123.2(5)°, N(3); 119.6(5)°, N(4). The mean exocyclic bond lengths are P—C, 1.77(1), P—F, 1.522(6), and the exoangles are 107.4(4)° (PMe2) and 97.2(3)°, (PF2). The bond lengths within the ring are well described in terms of simple perturbation theory, but comparison with the structures of other molecules shows the importance of factors other than π-electron distribution.

A series of thermotropic main chain liquid crystalline polyurethanes containing biphenyl mesogens and flexible methylene spacers were synthesized using the novel AB-type self-polycondensation approach for the first time.

A series of thermotropic main chain liquid crystalline polyurethanes containing biphenyl mesogens and flexible methylene spacers were synthesized using the novel AB-type self-polycondensation approach for the first time.

The reaction of methyl-lithium with the phosphonitrilic fluorides (NPF2)3–5follows a predominantly geminal course, the third and fourth substituents in the tetrameric ring entering antipodally to the first two. This behavior, and the competitive occurrence of an addition reaction, is attributed to the π-inductive effect of the substituents on a delocalized homomorphic π-system.