Data for Surface Relief Terraces in Double Gyroid-Forming Polystyrene-block-Polylactide Thin Films

This study describes the thin film self-assembly behavior of a polystyrene-block-polylactide (SL-G) diblock copolymer, which undergoes melt self-assembly in bulk into a double gyroid (DG) network phase with a cubic unit cell parameter a = 52.7 nm. Scanning electron microscopy (SEM) and grazing-incidence small-angle X-ray scattering (GISAXS) reveal that thermally annealing 140–198 nm thick copolymer films on SiO2 substrates below the morphological order-to-disorder transition temperature yields polydomain DG structures, in which the (422) planes are oriented parallel to the surface. Bright-field optical microscopy (OM) and atomic force microscopy (AFM) analyses further reveal the film thickness-dependent formation of topographical terraces, including islands, holes, and bicontinuous features. The occurrence of these features sensitively depends on the incommensurability of the as-prepared film thickness and the (211)-interplanar spacing (d211) of the DG unit cell. While the steps heights between adjacent terraces exhibiting characteristic “double wave” patterns of the DG (422) planes coincide with d211, previously unreported transition zones between adjacent terraces are observed wherein “boomerang” and “droplet” patterns are observed. These intermediate patterns follow the expected sequence of adjacent termination planes of the bulk DG unit cell along the [211] direction, as confirmed by comparisons with self-consistent mean-field theory calculations.

本研究阐述了聚苯乙烯-嵌段-聚丙交酯（polystyrene-block-polylactide, SL-G）二嵌段共聚物的薄膜自组装行为：该共聚物本体熔融自组装可形成立方晶胞参数a=52.7 nm的双 gyroid（double gyroid, DG）网络相。通过扫描电子显微镜（scanning electron microscopy, SEM）与掠入射小角X射线散射（grazing-incidence small-angle X-ray scattering, GISAXS）表征发现，在SiO₂基底上制备的140~198 nm厚共聚物薄膜，于低于其形貌有序-无序转变温度的条件下进行热退火，可得到(422)晶面平行于基底表面的多畴DG结构。明场光学显微镜（bright-field optical microscopy, OM）与原子力显微镜（atomic force microscopy, AFM）分析进一步揭示了薄膜厚度依赖的形貌台阶形成过程，其包含岛状、孔洞状及双连续状特征结构。这类特征结构的出现高度依赖于制备态薄膜厚度与DG晶胞(211)晶面间距（d211）的失配性。相邻台阶间的高度与DG(422)晶面典型“双波”图案特征一致，且恰好等于d211；同时还观测到此前未见报道的相邻台阶间过渡区域，其中存在“回飞棒”与“液滴”状图案。这些中间图案遵循体相DG晶胞沿[211]方向的相邻终止晶面的预期演化序列，该结论通过与自洽平均场理论（self-consistent mean-field theory）计算结果的对比得到了验证。