Photo-triggered large mass transport driven only by a photoresponsive surface skin layer
Photo-triggered large mass transport driven only by a photoresponsive surface skin layer
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DOI：
10.1038/s41598-020-69605-8
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发表时间：
2020-07-29
影响因子：
4.6
通讯作者：
Seki, Takahiro
中科院分区：
文献类型：
--
作者：
Kitamura, Issei;Kato, Keisuke;Seki, Takahiro
自25年前发现以来，许多研究报道了含偶氮苯聚合物膜的光诱导宏观质量迁移。已经提出了各种机制来解释这些运动。本研究探讨了光惰性侧链液晶聚合物（SCLCP）薄膜与光响应聚合物仅在自由表面和报告的最高表面的关键影响，以产生表面浮雕光栅（SRG）的SCLCP薄膜。采用Langmuir-Schaefer（LS）法或表面偏析法制备了含偶氮苯SCLCP的表面涂层。可忽略量的光响应皮肤层可以在图案化的UV光照射时诱导大的SRG。相反地，SRG形成偶氮苯SCLCP的运动受到顶部上十八烷基侧链聚合物的LS单层的存在的阻碍。通过考虑表面张力不稳定性驱动的Marangoni流，可以很好地理解这些结果。这种方法将为光惰性材料的表面形貌的原位铭刻铺平道路，并消除偶氮苯的强光吸收，这是光学器件应用中的一个缺点。
Since the discovery 25 years ago, many investigations have reported light-induced macroscopic mass migration of azobenzene-containing polymer films. Various mechanisms have been proposed to account for these motions. This study explores light-inert side chain liquid crystalline polymer (SCLCP) films with a photoresponsive polymer only at the free surface and reports the key effects of the topmost surface to generate surface relief gratings (SRGs) for SCLCP films. The top-coating with an azobenzene-containing SCLCP is achieved by the Langmuir-Schaefer (LS) method or surface segregation. A negligible amount of the photoresponsive skin layer can induce large SRGs upon patterned UV light irradiation. Conversely, the motion of the SRG-forming azobenzene SCLCP is impeded by the existence of a LS monolayer of the octadecyl side chain polymer on the top. These results are well understood by considering the Marangoni flow driven by the surface tension instability. This approach should pave the way toward in-situ inscription of the surface topography for light-inert materials and eliminate the strong light absorption of azobenzene, which is a drawback in optical device applications.