Synthesis Of Diamine Monomers Containing Naphthalene Structure And Their Application In Polyimide

Polyimide（PI）is a kind of high-performance polymer material.Flexible structure design and excellent gas separation properties make PI as an attractive membrane material in the field of gas separation.Like other gas separation membrane materials,gas permeability and selectivity are still limited by the trade-off relationship.The aromatic polyimide with ortho-hydroxyl group can form rigid rod-shaped polybenzoxazole structure after thermal rearrangement,which greatly improves the gas permeability and selectivity.In this thesis,two novel diamine monomers containing naphthalene ring structure were synthesized,and a series of o-hydroxy polyimide films and thermal rearrangement（TR）polymer films were prepared.（1）The diamine 1,5-bis（4-amino-5-hydroxyphenoxy）naphthalene（NDBAP）w as synthesized and polymerized with six kinds of dianhydride 3,3’,4,4’-biphenyl tetracarboxylic dianhydride（BPDA）,4,4’-（4,4’-isopropyldiphenoxy）dianhydride（B PADA）,1,2,3,4-cyclobutane tetracarboxylic dianhydride（CBDA）,4,4’-（hexafluoroi sopropyl）diphthalic anhydride（6FDA）,pyromellitic dianhydride（PMDA）and 3,3’,4,4’-diphenyl ether tetracarboxylic dianhydride（ODPA）for preparing PI membra nes.The results showed that the gas permeabilities increased with the increase of thermal rearrangement temperature.The gas permeabilities of TR（NDBAP-6F DA）-450 were 268.4,249.3,56.78 and 7.87 Barrer for H₂,CO₂,O₂and N₂,re spectively.The ideal selectivity for CO₂/N₂,O₂/N₂and H₂/N₂were 31.67,7.21and 34.1,which exceeded the 2008 Robeson upper limit of O₂/N₂.（2）A series of copolymer membranes were prepared by copolymerization of NDBAP,9,9’-bis（3-amino-4-hydroxyphenyl）fluorene（BAHPF）and 6FDA as monomers.The results showed that with the increasing content of BAHPF,the gas permeabilities of TR membrane increased.The gas permeabilities of H₂,CO₂,O₂and N₂of TR（NDBAP-BAHPF-6FDA）-6:4 were 354.88,374.36,95.12 and 13.09 Barrer,respectively,and the ideal selectivity of CO₂/N₂,O₂/N₂and H₂/N₂were 27.11,7.46and 28.22,approaching the 2015 upper limit of O₂/N₂.（3）The diamine 1,6-bis（4-amino-5-hydroxyphenoxy）naphthalene（NDBPA）was synthesized and polymerized with five kinds of dianhydrides（BPDA,BPADA,CBDA,6FDA,ODPA）to obtain five PI and TR membranes.The results indicated that the gas permeabilities increased with the increase of thermal rearrangement temperature.The gas permeabilities of TR（NDBPA-6FDA）-450 were 210.32,220.4,32.34 and 5.62 Barrer for H₂,CO₂,O₂and N₂,respectively,and the ideal selectivity of CO₂/N₂,O₂/N₂and H₂/N₂were 37.42,5.75 and 39.22,respectively,close to the 2008Robeson upper limit of O₂/N₂.（4）A series of copolymer membranes were prepared by copolymerization of NDBPA,BAHPF and 6FDA as monomers.After further heat treatment,TR membranes were obtained.The results reflected that the gas permeabilities of TR membrane increased with the increase of BAHPF content.The gas permeabilities of H₂,CO₂,O₂and N₂of TR（NDBPA-BAHPF-6FDA）-5:5 treated at 450°C were 244.5,278.9,45.78 and 6.53 Barrer,and the ideal selectivity of CO₂/N₂,O₂/N₂and H₂/N₂were 38.5,7.21 and 43.92 respectively,which exceeded the 2008 Robeson upper limit of O₂/N₂.