The synthesis of a 1,1′-bi-2-naphthol-based bis(ether anhydride) and aromatic polyimides derived therefrom * *This project was supported by the National Natural Science Foundation of China

Synthesis and Characterization of Processable Aromatic Polyimides

Two novel aromatic diamine monomers, Bis-4,4′[(4-aminophenyl-2,2′-isopropylidene phenyloxy)] diphenylsulfone and Bis-4,4′[(4-aminophenyl-2,2′-isopropylidene phenyloxy)] benzophenone were synthesized and characterized by IR and 1H-NMR. A series of processable polyimides were prepared by polycondensation of diamines with aromatic dianhydrides. The polyimides were characterized by infrared, 1H-NMR, X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, gel-permeation chromatography, solution viscosity and solubility. Polyimides were soluble in polar approtic solvents and increases in solubility in common organic solvents were observed due to the presence of flexible groups and methyl groups in the chain backbone. The polyimides exhibited good thermal stability, and the temperature at which 10% weight loss occurred ranged from 378 to 465 °C in nitrogen. X-ray diffraction measurements revealed that the polyimides were amorphous.

Synthesis and Characterization of New Fluorinated Polyimides derived from 9, 10-bis[3'-trifluoromethyl-4' (4''-aminobenzoxy) benzyl] Anthracene

A new diamine monomer 9,10-bis [3'-trifluoromethyl-4'(4''-aminobenzoxy) benzyl] anthracene (TFAA) was synthesized that led to a number of novel fluorinated polyimides by thermal imidization route when reacted with different commercially available dianhydrides such as 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhydride) (BPADA), 4,4'-oxydiphthalic anhydride (ODPA), 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA). These polyimides showed very high thermal stability with decomposition temperature (5% weight loss) 500— 550 °C in nitrogen depending on the exact structure. Transparent thin films of these polyimides exhibited tensile strengths of 40—74 MPa, a modulus of elasticity 2.33—2.9 GPa and elongation 5—10% depending on the exact polymer structure. Except for the polymer derived from PMDA, these polymers exhibited good solubility in common organic solvents. The polyimides showed absorbance spectra in the visible region and broad peak in photoluminescence spectra.

Synthesis and Characterization of Organosoluble Polysiloxaneimides Derived from Siloxane-containing Aliphatic Dianhydride and Various Aromatic Diamines

A new siloxane-containing monomer, 5,51- exo-(1,1,3,3,5,5-hexamethyl-trisiloxane -1,5-diyl) bisbicyclo[2,2,1]heptene-2,3- endo-dicarboxylic anhydride (3) was synthesized by the hydrosilylation reaction of 1,1,3,3,5,5-hexamethyl-trisiloxane (1) and cis-5-norbornene- endo-2,3-dicarboxylic anhydride (2). A series of organosoluble polysiloxaneimides (PI 5a-e) was prepared from the dianhydride 3 and several aromatic diamines 4 by a one-step high-temperature polycondensation method and the structures were characterized by IR and NMR. The effects of the main chain siloxane groups on the properties of PIs were evaluated by solubility, thermal stability and dielectric properties in addition to optical and water adsorption. The PIs were readily soluble in polar aprotic solvents such as NMP, DMAc and CHCl 3 at room temperature, except PI 5a, which was only soluble in polar amide type solvents at elevated temperature. PIs 5a-e had glass transition temperatures between 138 and 251°C in N2 and the 5% weight loss temperature ranged from 460 to 470°C under air. The PIs could be cast into flexible and tough films from DMAc solution. The films had tensile strengths of 44—52 MPa, tensile moduli of 0.56—0.68 GPa and elongations at break from 5.8—7.9%. The PI films exhibited good optical UV-vis transparency with wavelength cutoff of 269—289 nm and transmittances over 90% at 400 nm, and dielectric constants of about 2.76—2.65 with low water adsorption (0.3—0.4%).