拉曼Mapping成像研究聚苯乙烯/聚甲基丙烯酸甲酯共混体系的相态结构

Study on the phase structure of polystyrene/poly(methyl methacrylate)blend film by Raman Mapping imaging

利用拉曼光谱成像技术研究了聚苯乙烯/聚甲基丙烯酸甲酯(PS/PMMA)共混薄膜体系及其增容体系(增容剂为PS-b-PMMA嵌段共聚物)的相态结构及化学成分分布。实验结果表明,拉曼Mapping成像技术不仅可以得到PS/PMMA共混体系化学成分的精确分布图,同时也可以获取共混体系中分散相、界面相和连续相的分子指纹光谱。研究发现,共混体系中分散相和连续相组分分布与体系的组成紧密相关,当PS/PMMA质量比30/70时,分散相为PS,连续相为PMMA;当PS/PMMA质量比为50/50时,分散相为PS,但PS分子链仍存在于PMMA连续相中;当PS/PMMA质量比为70/30时,分散相为PMMA,连续相为PS。当增容剂PS-b-PMMA加入到PS/PMMA共混体系中后,分散相粒径减小、分布更加均匀、共混体系相容性指数(Nc)增大,说明PS/PMMA共混体系由完全不相容体系趋向变成半相容性体系,这是因为增容剂能增加PS和PMMA之间的相互作用,降低了体系的相分离程度,改善了共混体系的相容性。

In this paper,the phase structure and phase distribution of polystyrene/poly(methyl methacrylate)(PS/PMMA)blend with PS-b-PMMA block copolymer as the compatibilizer were studied by Raman spectroscopy imaging.The experimental results showed that Raman Mapping technology can not only provide accurate distribution of chemical components,but also give the molecular fingerprint spectra of dispersed phase,interface phase and continuous phase in the blend system.It is found that the phase structure of the blend system distributed in a“sea-island”form.When PS/PMMA=30/70,the dispersed phase was PS,and the continuous phase was PMMA;when PS/PMMA=50/50,the dispersed phase was PS,and PS also presented in the PMMA continuous phase;when PS/PMMA=70/30,the dispersed phase was PMMA,and the continuous phase was PS.The particle size of the dispersed phase decreased and distributed more uniformly when the block copolymer PS-b-PMMA was added into the PS/PMMA blend.Moreover,the semicompatible blends showed much smaller subphase distributions with less distinct interphase and increased compatibility number(Nc).It revealed that the compatibilizers could enhance the interaction between PS and PMMA,reduce the phase separation degree and improve the compatibility of the blend system.