Synthesis And Properties Of Soluble Photosensitive Polyimide

Polyimide(PI)is a kind of organic polymer material with good heat resistance,radiation resistance,mechanical,chemical and dielectric properties.Its excellent properties make it widely used in aerospace,microelectronics and optoelectronics.applications,especially in the field of 3D printing in recent years.Light-curing 3D printing technology is in the stage of rapid development,and the corresponding photosensitive polyimide(PSPI)has become a research hotspot.At present,the poor solubility of PSPI has become a major problem in the field of photocuring 3D printing.This paper investigates the application strategy and latest progress of photosensitive polyimide in the field of photocuring 3D printing.The diamine monomer structure is designed to achieve the purpose of improving the solubility of polyimide,and innovatively in the monomer stage The introduction of crosslinkable groups makes polyimide photocrosslinkable and further improves its solubility.First,a class of diamine monomers with a rigid spiro ring structure spiro[fluorene-9,9’-xanthene] as the core was designed and synthesized.Acid anhydride(6FDA)and3,3’,4,4’-benzophenone tetracarboxylic dianhydride(BTDA)were polymerized to prepare polyamic acid PAA1 and polyimide PI1,respectively.Two vertical nonconjugated units of fluorene ring and xanthene ring in spiro[fluorene-9,9’-xanthene]make it have a rigid structure of three-dimensional bulky sterically hindered,and a series of derivatives synthesized from it Both have high melting point and glass transition temperature,improve the thermodynamic stability of the molecule,inhibit the crystallization of the molecule,and help improve the solubility of the polymer.Secondly,the structures of PAA1 and PI1 were characterized by 1H-NMR,FT-IR,high-resolution mass spectrometry and other testing methods,and the structures of the synthesized monomers and polymers were determined.The optical properties,solubility and thermal properties of the polymer were tested by UV-Vis absorption,solubility test,thermogravimetric analysis(TGA)and other methods.The experimental results showed that the spiro[fluorene-9,9’-xanthene] structure The introduction of polyimide effectively improves the solubility of polyimide.Finally,on the basis of the previous work,a cross-linkable acrylic group was introduced into the diamine monomer,and a new type of cross-linking monomer was designed and synthesized.Polyamic acids PAA2,PAA3 and photosensitive polyimides PSPI2 and PSPI3 were prepared by polymerizing crosslinkable monomers with 6FDA and BTDA.The structures and properties of the monomers and polymers were characterized and tested.PSPI conducts photocuring experiments.The test results show that the PSPI series photosensitive polyimide has good photochemical properties and solubility,and can undergo photocrosslinking and curing under ultraviolet light irradiation,and has a good application prospect in the field of photocuring 3D printing.