Synthesis Pathway Of Polyimide
Polyimide variety, diversity, there are different ways in synthesis, therefore can be selected according to various application of variable connectivity, the synthesis is also difficult to have other polymer.
1.Polyimide is mainly composed of two yuan and two yuan amine anhydride synthesis, the two monomer and a number of other heterocyclic polymers, such as polybenzimidazole, polystyrene and dumb triazole, polybenzothiazole, poly of dumb phen and Polyquinoline monomers, wide source of raw materials, the synthesis is also easier. Two, two amine anhydride polyimide variety, different combinations can achieve different performance.
2.Polyimide can be composed of two anhydride and two amines in polar solvents, such as DMF, DMAC, NMP or THE/ by low temperature polycondensation mixed solvents of methanol, obtained polyamic acid soluble, film-forming or spinning after heating to 300 ℃ dehydration cyclization into polyimide; can also add acetic anhydride and tertiary amine catalysts to polyamide acid are chemical dehydration, cyclization, obtain polyimide solution and powder.Two amines and two anhydride can also in high boiling point solvent, such as heating phenolic solvent polymerization, a polyimide.In addition, also can obtain polyimide ester four yuan from two yuan and two yuan of amine acid；Can also be made of polyamide acid first into polyisoimide, and then converted to polyimide.These methods are convenient for processing, the former is called PMR method, can obtain low viscosity, high solid solution, with a low melt viscosity of the window in the process, the method is particularly suitable for manufacturing composite materials; the latter increased solubility, in the transformation process does not emit low molecular compounds.
3.As long as the two (or four acid anhydride) qualified and purity of two amines, using whatever polycondensation method, are very easy to obtain sufficiently high molecular weight, adding unit anhydride or amine unit can also be very easy to control the molecular weight.
4.In two (or four acid anhydride) and two amine condensation, as long as an equal molar ratio, heat treatment in vacuum, can improve the low molecular weight molecules pre solid polymer quantity greatly, so as to bring convenience and powder processing.
5. Easily in the end of the chain or chain into a reaction group to form active oligomer, resulting in thermosetting polyimides.
6.Using polyimide carboxyl, esterification or salt, get the amphiphilic polymer introducing photosensitive groups or long chain alkyl, can get the photoresist or for the preparation of LB film.
7.Synthesis of polyimide generally do not produce inorganic salt, the insulating material preparation is particularly advantageous.
soNorFifth,Flame retardant property
Polyimide polymer self quenching, smoking rate is low, the high vacuum outgassing rarely; stability in high temperature, high vacuum and irradiation, volatile matter little; flame retardant grade:
Can be used for the manufacture of tableware and medical equipment, and can withstand sterilization thousands of times, some polyimide has good biocompatibility. For example, in the blood compatibility test for non hemolytic, cytotoxic activity in vitro experiments for non-toxic. style= text-indent:0;mso-list:l0 level1 lfo1'10.Polyimide is non-toxic, can be used for the manufacture of tableware and medical equipment, and can withstand thousands of times disinfection. There are some polyimide has good biological compatibility, for example, in the blood compatibility test for non hemolytic, cytotoxic activity in vitro experiments for non-toxic.