pPDA／ODA-PMDA嵌段共聚酰亚胺薄膜的聚集态结构

Morphology of pPDA/ODA-PMDA Block Copolymer

通过控制2个组分的序列长度,制备了pPDA(对苯二胺)/ODA(4,4′-二氨基二苯醚)-PMDA(均苯四羧酸二酐)嵌段共聚酰亚胺(b-PI).采用偏光显微镜(PLM)、广角X射线衍射(WAXD)、透射电子显微镜(TEM)和力学性能测试研究了b-PI薄膜的聚集态结构.结果表明,所有b-PI薄膜均可结晶,生成微晶或不完善的小球晶.刚性棒状的pPDA-PMDA分子链段发生相分离,形成晶核,半刚性的ODA-PMDA分子链以pPDA-PMDA为晶核进行晶粒生长.在结晶过程中,晶核数目取决于pPDA/ODA比值及pPDA-PMDA(PP)链段长度,而晶粒尺寸依赖于ODA-PMDA链段(PO)的运动能力.通过调节二元胺的比例及2个嵌段组分的序列长度,可以对薄膜的聚集态结构实现可控制备,从而达到对性能的控制.

pPDA/ODA-PMDA block copolymers （b-PIs） with different segment length of two components were prepared. Morphology and properties of their films were investigated by polarizingmicroscope （ PLM）, wide-angle X-ray diffraction （ WAXD ）, transmission electron microscope （ TEM ） and tensil test. Measured results show all films of b-PI are crystalline. At first, phase separation of rigid segment of pPDA-PMDA takes place, forming nuclei. Then, semi-rigid segment of ODA-PMDA grows around the nuclei and forms small and imperfection grains. The number of nuclei is dependent of the ratio between pPDA and ODA and segment length of pPDA-PMDA（ PP）, while the size of grains is depended on the movability of ODA-PMDA（PO） segment. Morphology and properties of films can be controlled by changing the ratio of dianmines and segment length of two components.