Synthesis And Properties Of Polyimides Containing The Phthalazinone Moiety

In recent years, with the rapid development of high-technology industries,research of excellent processability and excellent thermal performance polyimides(PIs) has become an important research direction in advanced materials sciencebecause of its wide range of applications related to the photoelectric information，the field of microelectronics, aerospace and membrane separation. However, inmany cases they were insoluble and did not melt below the decompositiontemperature, which restricted their synthesis, characterizations, processing andapplication severely. From the molecular design, the design and synthesis ofnon-planar spatial structure of the asymmetric diamines or dianhydrides monomerswere used to prepare polyimide, improved polymer processing performance, withoutaffecting the polyimide resistance heat properties and chemical stability, in additionto access to certain functionality, and thus became a hot spot direction of thepolyimide modification and functional studies.This article was in-depth study to adhere to this idea, specifically, through thedesign and synthesis of unique distorted non-planar structure of the asymmetricdiamine monomer containing phthalazinone moiety, with two kinds of commercialdianhydride4’-(4,4’-isopropyl diphenoxy) bis (phthalic anhydride)(BPADA) and4,4’-diaminodiphenyl ether (ODA),to synthesis linear polyimides. Then, theimpact of changes in the polymer chain structure and substituent diamine phenolring of the polymers were explored. The specific content could be divided into thefollowing two aspects:1.Based on a series of six bisphenol-like compounds:1,2-dihydro-2-[4-(4’-hydroxyphenyl)] phthalazi-1-one,2’-methyl,3’-methyl-,3’-ethyl-,3’-isopropyl-, and3’,5’-dimethyl-substituted, reactions with4-chloronitrobenzeneresulted dinitro compounds, and six unsymmetrical diamines monomers withcorresponding reduction in high yields. The structures of the six monomers wereconfirmed by FT IR characterization. 2. Two series of polyimides were prepared from condensation between thesix diamine monomers and two commercial dianhydrides4,4’-(4,4’-isopropylidenediphenoxy) bis(phthalic anhydride)(BPADA) andbis-(3-phthalyl anhydride)ether(ODPA) by “low-temperature polycondensation andchemical cyclization” process. The structures of the PIs were confirmed by FT IRand1H NMR characterization. Illustrated by representative GPC tests, prepared PIshad high molecular weight. The PIs were easily soluble in the polar aprotic solvents(NMP, DMF, DMAC) and low boiling solvents (chloroform) and the chloroformsolution of these polymers could be cast into transparent and flexible films. Theinherent viscosities of the polymers were in the range of0.50~0.81dL/g. Moreover,the glass transition temperature (Tg) of the polymers were all above235oC and the10%weight loss temperatures of these polymers were in the range of445~523oC.The residual weight were in the range of51%~66%at800oC in nitrogen.