Synthesis and characterization of polyimides from 4-(diphenyl phosphine oxide)phenyl pyrromellitic dianhydride

Visible-light-induced ligand to metal charge transfer excitation enabled phosphorylation of aryl halides

We herein described a visible light induced nickel(II)-catalyzed cross-coupling of secondary phosphine oxides with aryl halides. The Ni(I) species and chlorine atom radical Cl˙ were generated via the ligand to metal charge transfer (LMCT) process of the NiCl2(PPh3)2, which allows nickel(IV)-phosphorus species in situ formation, giving various tertiary phosphine oxides under photocatalyst-free conditions.

Synthesis and characterization of novel fluorinated poly(ether imide)s containing pyridine and/or phenylphosphine oxide moieties

4-(4-Trifluoromethylphenyl)-2,6-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]pyridine (9FPBAPP), as a new aromatic diamine, was prepared by a modified Chichibabin reaction of 4-(4-nitro-2-trifluoromethylphenoxy)acetophenone with 4-triflouromethylbenzaldehyde, followed by a catalytic reduction. A series of fluorinated poly(ether imide)s containing pyridine and/or phenylphosphine oxide moieties were prepared from bis(3-aminophenyl)phenylphosphine oxide (BAPPO), 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), and 9FPBAPP via a conventional two-step thermal imidization procedure with various mole ratios of BAPPO and 9FPBAPP. All the polymers were amorphous and soluble in common organic solvents such as N, N-dimethylacetamide and N-methyl-2-pyrrolidone and had Tg’s of 277–285°C, 5% weight loss temperature of 521–550°C in nitrogen. Furthermore, high char yields and good limited oxygen index values indicated that these polymers exhibited good thermal stability and flame-retardant property. Tough and flexible polymer films also had good mechanical properties with tensile strengths of 75–99 MPa, tensile moduli of 1.1–1.6 GPa, and elongations at break of 12%–24% and low dielectric constants of 2.81–3.53 (1 MHz), as well as high optical transparency with the ultraviolet cutoff wavelength in the range of 350–384 nm.

P-Arylation of secondary phosphine oxides catalyzed by nickel-supported nanoparticles

Nickel-supported nanoparticles were used as catalysts for ligand-free Hirao coupling between secondary phosphine oxides and aryl halides.

Synthesis and properties of the novel polyimides containing cyano and biphenyl moieties

A series of cyano-functionalized polyimides (CN-PIs) were prepared and derived from a novel diamine monomer having cyano and biphenyl groups. Meanwhile, another series of PIs without cyano groups (H-PIs) were prepared as counterparts for comparison purposes. Both series of PIs exhibited good solvent resistance, good thermal stability, remarkable film-forming ability, and excellent tensile properties. The Tg values of CN-PIs were 260–330°C, which were 10–17°C higher than the corresponding –CN free H-PIs. The CN-PIs exhibited no obvious decomposition below 470°C, and their 5% weight loss temperatures were above 568°C under nitrogen atmosphere. All the CN-PI films had high tensile strength and Young’s moduli, which were related to their rigid backbones and strong interactions between molecular chains. Due to their higher molar polarization, CN-PIs expressed the higher dielectric constants (3.29–3.69 at 1 MHz) in comparison with the corresponding H-PIs. CN-PIs exhibited the improved transparency, and both CN-PIs and H-PIs had better transparency than commercial Kapton® film. Introducing –CN groups could have an effect on the coefficient of thermal expansion and peel strength of the PIs. The peel strength of the PI, which was derived from cyano-functionalized diamine monomer and 4,4′-oxydiphthalic anhydride, could even reach 1.10 N mm-1, suggesting its strong interaction to copper matrix and potential use in flexible circuit board.