Poly(amide imide)s containing functional nitrile groups for high performance materials

Cu(I)-Catalyzed addition-cycloisomerization difunctionalization reaction of 1,3-enyne-alkylidenecyclopropanes (ACPs)

A copper(i)-catalyzed three-component addition-cycloisomerization difunctionalization reaction of 1,3-enyne-ACPs with Togni I reagent and TMSCN under mild reaction conditions has been developed, affording 3-trifluoroethylcyclopenta[b]naphthalene-4-carbonitrile derivatives. The reaction proceeded through a copper(i)-catalyzed 1,4-addition of conjugated 1,3-enynes via a radical relay process and aromatic cycloisomerization of allene-ACP intermediates.

Copper-Catalyzed Radical 1,4-Difunctionalization of 1,3-Enynes with Alkyl Diacyl Peroxides and N-Fluorobenzenesulfonimide

Many reactions involving allenyl ion species have been studied, but reactions involving allenyl radicals are less well understood, perhaps because of the inconvenience associated with the generation of short-lived allenyl radicals. We describe here a versatile method for the generation of allenyl radicals and their previously unreported applications in the intermolecular 1,4-carbocyanation and 1,4-sulfimidocyanation of 1,3-enynes. With the assistance of the trifunctional reagents, alkyl diacyl peroxides or N-fluorobenzenesulfonimide, a range of synthetically challenging multisubstituted allenes can be prepared with high regioselectivity. These multisubstituted allenes can be easily transformed into synthetically useful structures such as fluorinated vinyl cyanides, lactones, functionalized allenyl amides, 1-aminonaphthalenes, and pyridin-2(1 H)-ones, and several novel transformations are reported. The results of radical scavenger and radical clock experiments are consistent with the proposed allenyl radical pathway. Density functional theory (DFT) and IR spectroscopy studies suggest the formation of an isocyanocopper(II) species in the ligand exchange step. On the basis of the results of IR, DFT, and diastereoselectivity studies, an isocyanocopper(II)/copper(I) catalytic cycle is proposed, which differs from the previously considered Cu(III) mechanism in cyanation reactions.

Low-Tg polyimides containing multiple ether linkages and cyano pendants

Some multi-ether linked polyimides (PIs) derived from two diamine monomers containing various amount of cyano groups are synthesized by a typical two-step polymerization. Meanwhile, the PIs with similar chemical structure but without cyano groups are prepared as counterparts for comparison purposes. The obtained PIs exhibit low glass transition temperature values of 211–258°C, which are associated with their multi-ether chemical structure. Furthermore, these PIs have high thermal stability, and the temperatures at 10% weight loss are in the range of 524–616°C under nitrogen atmosphere. It is found that the introduction of cyano groups would have a great influence on the properties of the PIs. The tensile strength and Young’s modulus of one cyano-containing PI reach 121 MPa and 1.4 GPa, respectively, which are much higher than those cyano-free ones. In addition, the cyano-containing PIs exhibit different behaviors of dielectricity and solubility in comparison with the corresponding cyano-free counterparts.

Synthesis and characterization of poly(amide-imide)s derived from a new ortho-functional unsymmetrical dicarboxylic acid

Herein, we report a new diacid monomer containing an imide ring and a methoxy pendant group, 3-trimellitimido-4-methoxybenzoic acid TMBA, for the preparation of poly(amide-imide)s.

Electromechanical properties of polyimide composites containing titanium dioxide nanotubes

Polyimide composite films were prepared by casting solutions resulting from direct mixing of a poly(amic acid) and titanium dioxide (TiO2) nanotubes (TNTs) onto glass plates, followed by thermal imidization. TNTs with outer diameters of approximately 10–12 nm and length of several hundreds of nanometers were synthesized by the hydrothermal method. The morphology of the nanotubes was investigated by using high-resolution transmission electron microscopy. The influence of TNTs content on structural, thermal, and electromechanical properties of pure polyimide and composite films was studied. The scanning electron microscopy and atomic force microscopy showed good compatibility between TNTs filler and polyimide matrix. The value of average roughness of film surface increases with increasing the content of TNTs. The films were flexible, tough, and exhibited high thermal stability. A study of microelectromechanical properties of these films was performed. The films showed nanometric displacements in the range of 250–800 nm when an electric voltage of 500 V was applied on their surface.

Synthesis and characterization of novel electrochromic poly(amide-imide)s with N,N′-di(4-methoxyphenyl)-N,N′-diphenyl-p-phenylenediamine units

Novel redox-stable and multi-colored electrochromic poly(amide-imide)s with N,N′-di(4-methoxyphenyl)-N,N′-diphenyl-p-phenylenediamine units were synthesized and characterized.

An anomalous trade-off effect on the properties of smart ortho-functional benzoxazines

A series of ortho-difunctional benzoxazine monomers containing amide, imide and amide–imide groups have been synthesized in order to obtain basic design rules toward preparing higher performance polybenzoxazoles based on smart benzoxazine chemistry.

Fabrication and characterization of novel highly transparent and organo-soluble poly(ether imide)s thin film for gas separation

New poly(ether imide)s with good solubility, film quality and thermal stability were synthesis for high-performance gas separation membrane by solution-casting.