Prediction of the glass transition temperature for compatible polymer blends of varying compositions

Compatible polymer blends have been found to have widespread commercial applications. The simplest criterion for judging polymer—polymer miscibility in the solid state is the glass transition temperature (T_g), which can vary widely according to blend composition for a compatible system.Recently, an equation which predicts the T_g of intimate mixtures of compatible polymers has been derived, based on classical thermodynamics. Only a knowledge of the T_g and heat capacity increment (ΔC_p) of each pure component is required to predict the T_g at any composition.In this paper, the validity of this entropy-based relationship is investigated for a variety of commercial compatible polymer blends, including some based on poly(vinyl chloride), polystyrene, and poly(2,6-dimethyl-,4-phenylene oxide). The T_g and ΔC_p of each pure component are measured with a Perkin-Elmer DSC-2 differential scanning calorimeter, are predicted glass transition temperatures are compared with those observed experimentally.     

BINAS - synthesis and use of a new ligand for propylene hydroformylation

BINAS is a new, very efficient ligand for propylene hydroformylation. BINAS is made by the sulfonation of NAPHOS. Different synthetic routes to NAPHOS are discussed. A new two step synthesis starting from 2,2′-bis(bromomethyl)-1,1′-binaphthyl is described.     

Über Blei-haltige Heterocyclen. II. Diphenyl-substituierte Thiaplumbocane,intra- und intermolekulare Koordinationserweiterung an tetraedrisch koordinierten PbIV -Atomen

On Heterocvclic Systems Containing Lead. II. Diphenyl Substituted Thiaplumbocanes, Examples for Expanding Coordination Tetrahedra around Pb^IV 5, 5-Diphenyl-1, 4, 6, 5-oxadithiaplumbocane (PbO8Ph2) and 2, 2-diphenyl-1, 3, 6, 2-trithiaplumbocane (PbS8Ph2) have been synthesized from diphenyl lead diacetate and the respective disodium dithiolates. The mass spectra point to rearrangements induced by reduction of Pb^IV to Pb^II in addition to fragments containing Pb^IV. ¹³C and ²⁰⁷Pb NMR spectra exhibit a weaker 1, 5-transannular interaction S …? Pb than O …? Pb. The crystal structures of two modifications of PbO8Ph2 (orthorhombic and triclinic) have been determined at ? 160°C and refined to R = 0.027 and 0.071. The two modifications contain four 8-membered rings crystallographical independent, three times chair-chair, once boat-chair conformation. Eight independent Pb^IV? S single bond distances range from 248.2(3) to 251.9(6) pm. The tetrahedral C₂PbS₂ configuration is expanded by one 1,5-transannular O …? Pb interaction (285,5(5) to 308(1) pm, monocapped) and further in the triclinic case by one intermolecular S …? Pb interaction (411(1) and 375(1) pm, bicapped). The crystal structure of the orthorhombic modification contains layers (8-membered ring) (phenyl)₂ analogous to the structure of CdI₂. In the triclinic case there are dimers arranged in analogy to the cubic closest packing.     

Advances in Organophosphorus Chemistry Based on Dichloro(methyl)phosphane

Besides phosphorus trichloride and phosphane, dichloro(methyl)phosphane is gaining importance as a starting material for the synthesis of organophosphorus compounds. It provides ready access to phosphonic, phosphinic and phosphonous acid derivatives, as well as their secondary products. The synthetic and application potential of organophosphorus compounds—based on industrially produced dichloro(methyl)phosphane—is illustrated by means of numerous examples.     

Probing the CH⋅⋅⋅π Weak Hydrogen Bond in Anesthetic Binding: The Sevoflurane–Benzene Cluster

Cooperativity between weak hydrogen bonds can be revealed in molecular clusters isolated in the gas phase. Here we examine the structure, internal dynamics, and origin of the weak intermolecular forces between sevoflurane and a benzene molecule, using multi‐isotopic broadband rotational spectra. This heterodimer is held together by a primary C? H???π hydrogen bond, assisted by multiple weak C? H???F interactions. The multiple nonbonding forces hinder the internal rotation of benzene around the isopropyl C? H bond in sevoflurane, producing detectable quantum tunneling effects in the rotational spectrum.