嵌段共聚物PCL-b-PMMA薄膜的微相分离形貌

通过开环聚合(ROP)和原子转移自由基聚合(ATRP)制备了不同嵌段结构的嵌段共聚物PCL-b-PMMA,使用核磁共振(1H-NMR)和凝胶渗透色谱(GPC)对其结构进行了表征,通过原子力显微镜(AFM)研究了嵌段共聚物薄膜的微相分离形貌。结果表明,嵌段共聚物发生了微相分离,聚ε-己内酯(PCL)链段形成柱状微区;PCL链段体积分数较低时,薄膜表面以聚甲基丙烯酸甲酯(PMMA)链段聚集为主,但未在PCL柱状微区上方形成覆盖,从而在薄膜表面形成孔洞;随PCL链段体积分数增加及PMMA链段分子量下降,PCL柱状微区面积增加,向薄膜表面迁移并逐渐形成覆盖,造成薄膜表面孔洞消失。

Microphase Separation and Morphology of PCL-b-PMMA in Thin Films

Diblock copolymers of ε-caprolactone methyl methacrylate(PCL-b-PMMA) with different block ratio and chain length of the block were prepared by ring-opening polymerization of ε-caprolactone,following atom transfer radical polymerization(ATRP) of methyl methacrylate,initiated with PCL-Br.The structures of the copolymers were characterized by 1H nuclear magnetic resonance spectrum(1H-NMR) and gel permeation in chromatography(GPC).Atomic force microscope(AFM) was used to investigate the morphologies of the block copolymers in thin films.It was found that microphase separation occurred for all block copolymers,and cylindrical morphology of PCL microdomains was formed.For PCL-b-PMMA with lower volume fraction of PCL,most of the surface of the film was covered with PMMA segments,except for the areas on top of the PCL cylindrical microdomains,generating many holes on the surface of the film.With the increase of PCL fraction and the decrease of the length of the PMMA segments,the PCL cylindrical microdomain increased and moved towards the top of the film,and finally covered the surface.