共混顺序对非对称两嵌段共聚物增容体系微观形貌的影响和机理探究

Research on Effect and Mechanism of Mixing Sequence on the Morphology of Asymmetric Diblock Copolymers Compatibilized Heterogeneous Polymer Blends

研究了熔融共混过程中共混顺序对非对称的聚苯乙烯-b-聚甲基丙烯酸甲酯嵌段共聚物(PS-b-PMMA,分别命名为SM1和SM2)增容聚苯乙烯/聚甲基丙烯酸甲酯(PS/PMMA)共混体系微观形貌的影响。扫描电镜(SEM)结果发现:合适的共混顺序可以导致分散相相尺寸的明显降低。为研究其增容机理,还选择了聚甲基丙烯酸环己酯/聚甲基丙烯酸甲酯(PCHMA/PMMA)共混体系,并以SM1为增容剂。透射电镜(TEM)结果发现:当SM1首先与连续相PCHMA混合再与PMMA混合,几乎全部的嵌段共聚物分散在共混界面上,增容效率极大提高;反之,SM1首先与分散相PMMA混合再与PCHMA共混,胶束形成并存在于PMMA相内,未起到增容作用。

The morphologies of heterogeneous polystyrene/poly（methyl methacrylate） （PS/PMMA） blends were modified by the addition of two asymmetric PS-b-PMMA diblock copolymers, respectively coded as SM1 and SM2, and investigated as a function of mixing sequences in the melt blending. SEM results show a sharp decrease in dispersed phase dimension is observed with the selection of desired mixing sequence in both blends. In order to study the mechanism of the compatibilization, poly（cyclohexyl methacrylate） and poly（methyl methacrylate） blends （PCH- MA/PMMA） were investigated with the addition of SM1. TEM results show that when SM1 was first mixed with PCHMA and blended with the dispersed PMMA, almost all of the block copolymers span the interface and improve the inteffacial adhesion. In contrast, when SMa was first mixed with the dispersed PMMA and then blended with PCHMA, aM1 form in micelles, exist in the dispersed PMMA phase and thereby lead to lower compatibility.