A separator for a rechargeable battery includes a porous substrate and a heat-resistance layer disposed on at least one surface of the porous substrate, wherein the heat-resistance layer includes a cross-linkable binder, and the cross-linkable binder is derived from a polymer including a structural unit including an aromatic moiety and a (meth)acrylate group; and a rechargeable lithium battery includes the same.

A method for using citraconic anhydride and itaconic anhydride as addition cure end caps in reactions for forming polyamic acid oligomers and polyimide oligomers, is provided. Prepregs and high temperature adhesives made from the resulting oligomers, as well as, high temperature, low void volume composites made from the prepregs, are also provided.

Non-straight ducts for conducting fluids at temperatures higher than 280 C. and pressures higher than 4 bar made of a composite material and, particularly, hot air bleed ducts of an aircraft made of a carbon-fiber reinforced polymer aimed to reduce weight of the bleeding system by replacing most of the metallic material from which the bleeding ducts are currently made.

The present invention provides a porous polyimide or polyimide wet gel with excellent physical properties. One aspect provides a porous polyimide in which an average pore size (d) obtained by using small-angle x-ray scattering is 1.0 nm to 7.0 nm. One aspect provides a porous polyimide in which the minimum value of the differential coefficient when the logarithmic value log[I(q)] of the scattering intensity I(q) is differentiated by the logarithmic value log[q] of the scattering vector q is 1.0 to 0.0 within a range in which the size of the scattering vector q in small-angle x-ray scattering is 0.025 nm.sup.1 to 0.075 nm.sup.1.

A self-sensitizing negative polyimide precursor and a method for preparing the same, and use thereof. 4,4-dinitro-1,1-biphenyl-2,2-dicarboxylic acid is used as a starting material and undergoes an acylation reaction with thionyl chloride to afford compound 1. Compound 1 subsequently undergoes an esterification reaction with 2-hydroxyethyl methacrylate to afford compound 2. The nitro groups of compound 2 are then reduced to amino groups; after purification, an intermediate of the self-sensitizing negative polyimide precursor is obtained. The intermediate is polymerized with 3,3,4,4-benzophenone tetracarboxylic dianhydride to give a polyamic acid, namely the self-sensitizing negative polyimide precursor. Because the intermediate contains a benzophenone moiety, ultraviolet irradiation can generate free radicals, allowing the intermediate to act intrinsically as a photoinitiator. The dual photosensitive properties of the ketone carbonyl and double bond in the self-sensitizing negative polyimide precursor material provided by the present application can improve the exposure sensitivity of the resin.

The present disclosure provides a method of fabrication of physically crosslinked polyimide (PCPI) aerogels with significantly improved properties using no chemical crosslinker. The fabricated PCPI aerogels present high moisture resistance, hydrophobic behavior, ultralow density, ultrahigh porosity, excellent thermal stability, increased mechanical strength, and high mechanical flexibility. Also, samples have been successfully fabricated in a thin-film geometry with high mechanical flexibility and controlled thickness. Furthermore, some fabricated aerogel films present improved optical transparency of over 80%, which is the highest transparency reported so far for organic PI aerogels.

Provided is a porous polyimide composition having low colorability and high light transmittability. Provided is a porous polyimide composition, in which an average pore size (L) obtained by the following expression based on a pore volume (V) and a BET specific surface area (A) determined by a gas adsorption method: L=4V/A; is 5 nm or more and 500 nm or less, a light transmittance at 450 nm at a film thickness of 1 mm is 10% or more and 100% or less, and a degree of polymerization (n) is 5 or more and less than 40.

Aerogels comprising a hydrophobic polyimide moiety, including hydrophobic polyimide aerogels, as well as methods of manufacture and applications thereof, are generally described.

In one aspect, the disclosure relates to azide-containing poly(ether imide) polymers (PEIs; N.sub.3-PEI-N.sub.3) synthesized via a heterogenous diazotizationazidation reaction. In one aspect, the azide-containing PEIs can be solution-cast into films and then thermally crosslinked. In a further aspect, the crosslinked PEIs (X-PEIs) exhibit superior thermal and mechanical properties. In a still further aspect, X-PEIs display outstanding resistance to classical solvents for conventional PEI, including THF, DCM, chloroform, DMF, and NMP. In another aspect, with an initial number average molecular weight (M.sub.n) of 8.9 kDa, the disclosed azide-containing PEIs have a high crosslinking density and thus possess desirable thermal, mechanical, and solvent resistance properties.

A polyimide oligomer and a preparation method therefor, and a cured product having low-dielectric properties prepared therefrom. The polyimide oligomer has a structure as represented by formula (I) or formula (II), and the symbols in formula (I) and formula (II) are as defined in the description. Therefore, a dimer diamine is used to match a specific monomer and a ratio is adjusted, so as to prepare a free-radical-curable polyimide oligomer; and same has good thermal properties and excellent low-dielectric properties after being cured, so as to be used in the industry of high-frequency circuit boards.

##STR00001##