反相非水乳液法制备聚酰亚胺微球

在N,N-二甲基甲酰胺(DMF)/Pluronic-F127、十二烷基苯磺酸钠(SDBS)/液体石蜡(LP)反相非水乳液体系中,以均苯四甲酸二酐(PMDA)和4,4′-二氨基二苯醚(ODA)为单体合成聚酰胺酸(PAA),采用吡啶/乙酸酐脱水剂,对PAA化学酰亚胺化,并进一步热酰亚胺化,制得PI耐热微球.产物通过红外、热重、扫描电镜表征.结果表明,较高的固含量和良好的乳液分散性有利于PI微球的形成;反相非水乳液体系稳定的配比条件是,VDMF∶VLP为1∶4,MF127∶MSDBS为3:2,乳化剂用量为9 wt%;在此配比条件下,当固含量为20%,热酰亚胺化温度不高于330℃时,可制得分散良好、球形规整、高热稳定性的PI微球,其粒径约为10μm.

PREPARATION OF POLYIMIDE MICROSPHERES IN NON-AQUEOUS INVERSE EMULSION

A method was presented to prepare polyimide microspheres in non-aqueous inverse emulsion.The non-aqueous inverse emulsion was compounded with N,N-dimethyl formamide /(pluronic-F127,dodecylbenzenesulf) /liquid paraffin,in which the poly(amic acid) was synthesized with monomers of pyromellitic dianhydride and 4,4′-diaminodiphenyl ether.Then the polyimide particles were precipitated through the chemical imidization using the acetic anhydride /pyridine mixture as dehydrating agent.Ultimately,polyimide particles were completely imidized via thermal imidization.The stability of non-aqueous inverse emulsion were investigated,and the effects of solid content and thermal imidization temperature on the morphology of polyimide microspheres were also discussed.The properties of the product were characterized with FTIR,SEM and TG /DTG.The results showed that it was favorable to form the polyimide microspheres with higher solid content and better emulsion dispersity.The non-aqueous inverse emulsion was optimal when the volume ratio of N,N-dimethyl formamide to liquid paraffin was 1 ∶ 4,the mass ratio of pluronic-F127 to dodecylbenzenesulf was 3 ∶ 2,and the content of emulsifiers was 9 wt%.In addition,the polyimide particles were well dispersive,spherical and highly thermal stable with a narrow size distribution when the solid content was 20% and the thermal imidization temperature was less than 330℃.The average particle diameter was about 10 μm.