(1)采用“二次模板”法制备,首先使用20 um PS 微球制备出逆反射结构色薄膜(RSCF)[5]模板(一次)。然后将聚二甲基硅氧烷(PDMS)预聚体及其固化剂按照10:1 的质量比混合均匀后涂敷在20 um-RSCF 模板上,静置2 h 待气泡消失,置于50摄氏度 干燥箱中加热24 h 后揭下,制备出上层PDMS 模板(二次);
(2)将75 wt%的A 胶与25 wt%的B 胶混合均匀后,涂敷在PDMS 模板上,之后将整体放入真空干燥箱中脱气10 min 以去除气泡;
(3)将整体放置于60摄氏度 干燥箱中加热3 h 后,升温至100摄氏度 继续加热1 h,待冷却后揭下PDMS 模板,即可得到具有单面穹顶(直径为20 μm)单层阵列结构的形状记忆逆反射结构色薄膜;
(4)将薄膜的一半放置在载玻片和具有空心“D”图案的掩模板中间形成“载玻片-薄膜-掩模板”的三明治结构,一起放入平口钳中;
(5)整体放置于85摄氏度 干燥箱中预热30 min 后热压5 min,保压状态下冷却至室温,即可得到一半无图案,一半有“D”图案的PRSCF(20 μm-PRSCF);
(6)同样,使用带有空心“F”图案的掩模板处理10 μm-薄膜,使用带有空心“U”图案的掩模板处理15 μm-薄膜,可得到一半无图案,一半有“F”图案的10 μm-PRSCF 和一半无图案、一半有“U”图案的15 μm-PRSCF。
An original shape memory polymer-based retroreflective structural color film was fabricated according to the previous method. Then, about half of this film was placed between a glass slide and a patterned mask (i.e., a “slide-film-mask” sandwich model), and put into a flat-nose plier and preheated at 85 °C (above the glass transition temperature (Tg) ≈ 68 °C; Figure S9, Supporting Information) for 30 min, and then pressed under 4 MPa for 5 min. After that, the film was cooled to room temperature under pressure.The PRSCF was placed on the backboard with its plane side upward. For noncoaxial conditions, the PRSCF was photographed at different angles by moving the camera only. For coaxial conditions, the PRSCF was photographed at different angles by moving the camera and light source simultaneously.