Synthesis pathway polyimide
Polyimide variety, in various forms, in the synthesis of a variety of ways, it can be selected according to various application purposes, this synthetic variable continuity on the other polymers are also difficult to have.
1. Polyimide mainly diamine and a dibasic acid anhydride synthesis, two monomers with numerous other heterocyclic polymers, such as polybenzimidazole, polybenzoxazole dumb yl, polybenzthiazole polyquinoline dumb Compare morpholine and polyquinoline monomer such as a wide source of raw materials, synthetic and easy. Dianhydride, diamine wide variety of different combinations of different properties can be obtained polyimide.
2. May be formed of a polyimide dianhydride and a diamine in a polar solvent, such as DM F, DMAC, NMP, or TH E / methanol mixed solvent of low temperature polycondensation to obtain a polyamic acid soluble, film forming or spinning after heating to about 300 ℃ dehydration ring into polyimide; may also be added acetic anhydride and the tertiary amine catalyst to the polyamic acid, the chemical dehydration cyclization to obtain a polyimide solution and a powder. Dianhydride and a diamine in a high boiling solvent may also be, in a solvent such as phenolic condensation heating step to obtain a polyimide. It can also consisting of a quaternary dibasic acid esters and diamine reaction to obtain a polyimide; and to be the first polyamide acid into polyimide polyisoprene, and then converted to the polyimide. These methods are the processing convenience, the former is called PMR method, you can obtain a low viscosity, high solid content solution in the processing window has low melt viscosity has a particularly suitable for the manufacture of composite materials; the latter increase solubility, in the process of transformation does not release low molecular weight compounds.
3. Just dianhydride (or four acid) and diamine purity qualified Regardless condensation method, are easy to obtain a sufficiently high molecular weight, adding unit anhydride or amine unit also can easily regulate the molecular weight.
4. To anhydride (or four acid) and diamine condensation, the molar ratio of long to achieve first-class, in a vacuum heat treatment, can greatly improve the low molecular weight solid pre-polymer molecular weight, giving processed and brought into powder Convenience.
5. Is easy to introduce reactive groups on the side chain or chain to form an active oligomers to obtain a thermosetting polyimide.
6 Use polyimide carboxyl group, esterification or salt formation, the introduction of photosensitive groups or amphiphilic polymers to obtain long-chain alkyl, or photoresist can be used for the preparation of LB films.
7. General Synthesis of polyimide process does not produce inorganic salts, for the preparation of an insulating material is particularly advantageous.
8. As the dianhydride and diamine monomer easy sublimation under high vacuum, it is easy polyimide film vapor deposition method is formed on the workpiece, in particular the use of the uneven surface of the device.