我們已經研究對稱型且弱分離的嵌段共聚物—聚苯乙烯-b-聚（甲基丙烯酸甲酯），及其與低分子量均聚物—聚苯乙烯的混合物在混摻比例下的薄膜相行為。通過熱退火過程，根據混合物中均聚物的不同含量，獲得了幾種形態。為了觀察薄膜的內部結構並增加PS和PMMA域之間的對比度，使用氧氣等離子體蝕刻選擇性地去除了PMMA塊和PS表層。借助光學顯微鏡（OM）、原子力顯微鏡（AFM）、掃描式電子顯微鏡（SEM）、低掠角小角度 X 光散射技術（GISAXS）仔細識別了薄膜結構。這些獲得的形態包含穿孔層（Perforated Layer, PL）、雙連續螺旋（bicontinuous Double Gyroids, DG）、圓柱（Cylinder, C）等結構。穿孔層和雙連續螺旋僅存在於一個狹窄的體積分率。除了PS混合比例以外，空間侷限效應和熱退火溫度也會影響穿孔層和雙連續螺旋之間的相穩定性。在薄膜中，聚苯乙烯-b-聚（甲基丙烯酸甲酯）和聚苯乙烯的複雜二元相混摻的存在可歸因於通過添加聚苯乙烯來減輕packing frustration。;We have demonstrated the phase behavior in thin films of a symmetric weakly-segregated block copolymer, polystyrene-block-poly （methyl methacrylate）, PS-b-PMMA, and its mixtures with a low molecular weight homopolymer （polystyrene, PS） at different blending ratios. Through thermal annealing, several morphologies were obtained, depending on the different contents of homopolymer PS in the mixtures and annealing temperatures. To observe the inner structures in thin films and to increase the contrast between the PS and PMMA domains, oxygen plasma etching was used to selectively remove the PMMA block and PS skin layer. The thin film structures were carefully identified by means of optical microscopy（OM）, atomic force microscopy（AFM）, scanning electron microscope（SEM） and grazing-incidence small-angle X-ray scattering（GISAXS）. These obtained morphologies include perforated layers（PLs）, double gyroids（DGs）and cylinders（Cs）. PLs and DGs only existed in a narrow region. In addition to the blending ratios, spatial confinement effects and annealing temperatures also affected the phase stability between PLs and DGs. The presence of complex binary phases in thin blend films of PS-b-PMMA/PS is ascribed to alleviation of packing frustration through the addition of PS.
