Novel Synthesis And Properties Of Polyimide Based Triptyl Structure

Polyimides are a class of high performance polymers containing imide ring in themain chain. Due to its outstanding chemical, physical properties such as heatresistance, low dielectric constant, resistance to chemical corrosion, etc., are widelyused in aerospace, advanced composite material, separate film, microelectronicdevices, and many other fields. As one of representatives of heat-resistant polymermaterials, since the first reported in1908, polyimide has experienced more than acentury of development, because there is a high glass transition temperature, itsrefractory and dissolution, lead to problems such as difficult to machining, whichlimits the development of polyimide materials and the expansion of application fields.In this paper we succeed introducing the triptycene structure to main chain ofaromatic polyimides through molecular design and synthesis, get a series ofpolyimides with perfect thermal performance, and batter solubility. Major innovationsin the following:(1)In this paper, we designed and synthesized a new dianhydride monomertriptycene-2,3,6,7-tetracarboxylic acid dianhydride, based on molecular design.2,3,6,7-tetramethylanthracene and benzyne generated in situ from anthranilic acidunderwent a Diels-Alder reaction to give2,3,6,7-tetramethyltriptycene, Subsequentoxidized by KMnO4, dehydration under vacuum to afford a new dianhydridetriptycene-2,3,6,7-tetracarboxylic acid dianhydride. Structures of all thesecompounds were characterized by FT-IR and1H NMR spectrum.(2)A series of novel type of structure ofpolyimides (PIs) was synthesized fromtriptycene-2,3,6,7-tetracarboxylic dianhydride and para-phenylenediamine (PPDA),4,4’-diaminodiphenylmethane (DMA),4,4’-diaminodiphenylether (ODA) and thenovel diamine monomer2,6-diaminotriptycene (DAT) via low temperature solutioncondensation polymerization and chemical imidization. The structure and propertiesof the obtained polyimide were characterized by FT-IR, TGA and DSC. and thesolution property was also taken into account. The results shows that the PIs are soluble in the polar solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc). Compared with other polyimides, the polymer PId get bettersolubility, it can also be solved in m-cresol. The decomposition temperature (Td) forthe aromatic polyimide at5%weight loss are above511oC; and no glass transitiontemperatures can be found below300oC; and high weight residues at800°C upon to65%. And the decomposition temperature (Td) for the polymer PId at5%weightloss is403oC; and high weight residues at800°C only39%. the thermalperformance is decreased significantly.