三元共聚聚酰亚胺薄膜的制备与性能

Preparation and properties of ternary copolyimide films

以4,4'-二氨基二苯甲烷(DDM)、4,4'-二氨基二苯醚(ODA)、均苯四甲酸酐(PMDA)为原料,通过改变DDM和ODA的物质的量比,制备了DDM含量(占整个二胺单体物质的量分数)分别为0%,25%,50%,75%的三元共聚聚酰亚胺薄膜,探究不同含量DDM的引入对聚酰亚胺薄膜物理力学性能的综合影响。结果表明,合成的聚酰亚胺材料已经完全亚胺化;随着DDM含量从0%增加到75%,质量损失5%时分解温度从357.6℃升高至531.2℃;引入DDM单体后聚酰亚胺薄膜在可见光(400~800 nm)范围内透过率均达到85%以上,此外由于DDM中亚甲基这一非极性基团的引入,使得聚酰亚胺薄膜的疏水性增强,接触角由未加DDM时的66.9°最高上升至92.1°;DDM的引入使得聚酰亚胺薄膜分子链中氢键的相互作用增强,在第三单体DDM含量为50%的条件下,薄膜的拉伸性能和导热性能最好,拉伸强度为192.46 MPa,断裂伸长率为10.23%,拉伸弹性模量为3.83 GPa,热导率由未加DDM时的0.348 W/(m·K)升高至0.399 W/(m·K),相比未加入DDM的聚酰亚胺分别提高了48%,42%,56%和15%。综上分析,该三元共聚聚酰亚胺薄膜在力学、导热性和透明度等性能方面具有良好表现,可广泛应用于电子元件的散热与航天器防护等领域。

Using 4,4'-diaminodiphenyl methane(DDM),4,4'-diaminodiphenyl ether(ODA)and homophenyltetramethylene anhydride(PMDA)as raw materials,by changing the molar ratio of DDM and ODA,ternary copolyimide films containing different DDM contents with 0%,25%,50%and 75%(DDM content is mole fraction of DDM in diamine monomers)were prepared.The comprehensive influences of DDM content on physical and mechanical properties of the polyimide films were investigated.The results show that the imidization of the synthesized polyimide material is completely finished.With the increase of DDM content from 0%to 75%,the temperature at 5%thermal weight loss increases from 357.6℃to 531.2℃.After the introduction of DDM monomer,the transmittance of the polyimide films in the range of visible light(400-800 nm)is more than 85%.In addition,the hydrophobicity of the polyimide films is enhanced due to the introduction of a non-polar group(methylene)in DDM,and the contact angle increases from 66.9°(without DDM)up to 92.1°.The hydrogen bond interaction in polyimide films was enhanced with the introduction of DDM.Under the condition that the third monomer DDM content is 50%,the tensile properties and thermal conduc-tivity of the film are the best,the tensile strength is 192.46 MPa,the elongation at break is 10.23%,the tensile modulus is 3.83 GPa,and the thermal conductivity increases from 0.348 W/(m·K)(without DDM)to 0.399 W/(m·K),which are increased by 48%,42%,56%and 15%respectively compared with those of the polyimide film without DDM.In summary,the ternary copolyimide film has good performance in mechanics,thermal conductivity and transparency,and can be widely used in the field of heat dissipation of electronic components and spacecraft protection.