PCL-b-PMMA／PEO共混薄膜的微相分离形貌

Microphase Separation Morphologies of PCL-b-PMMA/PEO Blending Films

通过聚氧化乙烯(PEO)与聚己内酯-聚甲基丙烯酸甲酯嵌段共聚物(PCL-b-PMMA)的共混来调节聚己内酯(PCL)与聚甲基丙烯酸甲酯(PMMA)嵌段的微相分离行为。采用原子力显微镜研究了PEO的质量分数和相对分子质量对PCL-b-PMMA/PEO共混薄膜微相分离形貌的影响。结果表明,共混薄膜形成了以PMMA/PEO为连续相,PCL呈柱状微区垂直于薄膜表面的微相分离形貌,PMMA/PEO链段无法在PCL柱状微区上方形成完全覆盖,导致薄膜表面形成许多孔洞。随着PEO含量增加,PCL链段聚集趋势增强,柱状微区尺寸不断增大;随着PEO相对分子质量的增加,PMMA/PEO在PCL微区上方形成的有效覆盖减少,薄膜表面的孔洞数量和尺寸增大;当PEO与不同嵌段比PCL-b-PMMA共混后,随嵌段共聚物中PCL链段体积分数增加,柱状微区向层状形态转变,薄膜表面孔洞消失。

Poly（ethylene oxide） （PEO） blended with diblock copolymers of ε-caprolactone and methyl methacrylate （PCL-b-PMMA） in order to modify microphase separation behavior and morphologies in PCL-b-PMMA/PEO blending film. Effects of PEO mass fraction and relative molecular mass on the microphase separation morphologies of PCL-b-PMMA/PEO thin films were investigated by AFM. The results show that microphase separation morphologies with PMMA/PEO as continuous phase and cylindrical microdomains of PCL oriented perpendicularly to the film surface were formed. The top of PCL cylindrical microdomains cannot be completely covered by PMMA/PEO segments, generating many holes on the surface of the film. With the increase of PEO content, the size of cylindrical microdomain of PCL increases due to the enhanced aggregation of PCL segments. When PEO with higher relative molecular weight was used, the efficient cover on the top of the PCL cylindrical microdomains with PMMA/PEO segments becomes less, leading to increased number and the size of holes on the surface of the film. As the volume fraction of PCL segments in PCL-b-PMMA increases, more PEO segments move towards the top of the film, giving rise to a transition of cylindrical microdomain of PCL to lamellar morphology, and finally the holes on the surface of the films disappear.