International audienceNew soluble polyimides were prepared from a series of diamines and a tetracarboxylic dianhydride with a benzhydrol unit, 3,3‘,4,4‘-benzhydrol tetracarboxylic dianhydride (BHTDA), by one-step method polymerization. The diamines containing flexible units, bulky substituents, and/or noncoplanar conformation unit were prepared by the reaction of the corresponding bisphenol precursors and p-chloronitrobenzene, followed by catalytic reduction of the dinitro compounds. The polyimides obtained were soluble in various solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, pyridine, γ-butyrolactone, m-cresol, and even tetrahydrofuran except for polymer PId. The polymers were amorphous and had number-average molecular weight (n) in the range (3.0−10.2) × 104. The glass transition temperatures (Tg) of the polymers ranged from 268 to 341 °C. These polymers exhibited good thermal stability without significant weight loss up to 420 °C. The temperatures at 10% weight loss range from 457 to 524 °C in nitrogen and 449 to 519 °C in air, respectively. The polyimide films were found to be transparent, flexible, and tough. The films had a tensile strength range 72−105 MPa, an elongation range at break of 4−7%, and a Young's modulus range of 2.18−2.85 GP

In the present paper, we describe the synthesis and characterization of a novel negative-type soluble photosensitive polyimide (PSPI). A group of new photosensitive polyimides has been prepared by condensation of dianhydrides bearing photoreactive ester groups and aromatic diamines in N-methylpyrrolidone (NMP), followed by chemical imidization using acetic anhydride without acid acceptors such as pyridine or triethylamine. Thus, the starting monomer used in the synthesis of a commercial aromatic polyimide has been chemically modified with four different photosensitive groups (chlorine-free synthesis). All the intermediates as well as the resulting polymers have been characterized. The PSPI esters were found to be soluble in N-alkyl-substituted amides. Their irradiation with UV light induces cross-linking of the photoreactive ester groups. These systems change from being weakly to being heavily cross-linked during irradiation and do not swell during development. The remaining PSPI esters do not require thermal imidization because they are already imidized, and shrinkage is about 20% due to volatilization of photoreactive groups.

No abstract