Liquid Crystalline Polymorphism of 4-Alkyloxybenzylidene-4'-Alkyloxyanilines and Entropic Effects of Their Phase Transitions

This paper summarizes liquid-crystalline polymorphism of the asymmetrical 4-alkyloxybenzylidene-4'-alkyloxyanilines. In this group, containing 121 compounds, 6 types of mesophases were detected: nematic, smectic A, smectic C, smectic B, smectic I, and smectic G. Influence of both alkyl chain length on the type of mesophases and entropic effects of phase transitions are discussed

Liquid Crystalline Polymorphism of 4-Alkyloxybenzylidene-4'-Alkyloxyanilines and Entropic Effects of Their Phase Transitions

This paper summarizes liquid-crystalline polymorphism of the asymmetrical 4-alkyloxybenzylidene-4'-alkyloxyanilines. In this group, containing 121 compounds, 6 types of mesophases were detected: nematic, smectic A, smectic C, smectic B, smectic I, and smectic G. Influence of both alkyl chain length on the type of mesophases and entropic effects of phase transitions are discussed

SET-LRP of vinyl chloride initiated with CHBr 3 in DMSO at 25 °C

The development of Cu(0)/TREN/CuBr -catalyzed SET-LRP of VC initiated with CHBr in DMSO at 25 °C is reported. The use of CuBr additive allows for the first LRP of low molecular weight VC (target DP = 100), as well as lower Cu powder loading levels, improved I and control in the synthesis of higher molecular VC, targeted degree of polymerization = 350, 700, 1,000, 1,400. H NMR and HSQC confirm the bifunctionality of CHBr as an initiator and suggest that deleterious sidereactions such as the formation of allylic chlorides occur primarily at the onset of the reaction

Ultrafast synthesis of ultrahigh molar mass polymers by metal-catalyzed living radical polymerization of acrylates, methacrylates, and vinyl chloride mediated by SET at 25 degrees C

Conventional metal-catalyzed organic radical reactions and living radical polymerizations (LRP) performed in nonpolar solvents, including atom-transfer radical polymerization (ATRP), proceed by an innersphere electron-transfer mechanism. One catalytic system frequently used in these polymerizations is based on Cu(I)X species and N-containing ligands. Here, it is reported that polar solvents such as H2O, alcohols, dipolar aprotic solvents, ethylene and propylene carbonate, and ionic liquids instantaneously disproportionate Cu(I)X into Cu(0) and Cu(II)X-2 species in the presence of a diversity of N-containing ligands. This disproportionation facilitates an ultrafast LRP in which the free radicals are generated by the nascent and extremely reactive Cu(0) atomic species, while their deactivation is mediated by the nascent Cu(II)X-2 species. Both steps proceed by a low activation energy outer-sphere single-electron-transfer (SET) mechanism. The resulting SET-LRP process is activated by a catalytic amount of the electron-donor Cu(0), Cu2Se, Cu2Te, Cu2S, or Cu2O species, not by Cu(I) X. This process provides, at room temperature and below, an ultrafast synthesis of ultrahigh molecular weight polymers from functional monomers containing electronwithdrawing groups such as acrylates, methacrylates, and vinyl chloride, initiated with alkyl halides, sulfonyl halides, and N-halides