Development of photo-responsive flexible nano actuator for peristeric movement

在DMF中合成了以4,4′二氨基偶氮苯（DAA）为骨架的光响应性聚酰胺酸（PAA）和聚酰亚胺（PI）凝胶，并利用扫描显微光散射（SMILS）研究了光照射引起的网目尺寸变化。以4,4′-（六氟异丙基）二苯二酸酐（6FDA）、4,4′-氧化二苯酐（ODPA）、邻苯二酸酐（PMDA）为原料，与三官能团胺1,3,5-三（4-氨基苯基）苯（TAPB）端交联制备了三种不同的酰胺类低聚物。以PAA(OAA（6FDA/DAA)(4/3)-ν-TAPB）凝胶为例，smil显示，偶氮苯由纳米级转化为顺式的光异构化导致的网目尺寸变化为2.1 ~ 0.83 nm，与光照射下偶氮苯分子长度的变化相对应。此外，从宏观上发现，这种直径为0.2 mm的棒状聚酰胺酸凝胶在蓝色激光照射下可以快速剧烈地偏转，在可见光照射下可以可逆地变直。这种光致各向同性聚合物凝胶棒的宏观弯曲是通过在聚合物网络的主链中引入刚性芳环来实现的。通过制备聚酰胺酸管，研制了一种用于光致蠕动的柔性纳米驱动器。

Photoresponsive poly(amide acid) (PAA) and polyimide (PI) gels consisting of 4, 4' diamino azobenzene (DAA) in backbone were synthesized in DMF, and mesh-size changes induced by photoirradiation were investigated by using scanning microscopic light scattering (SMILS). Three different kinds of amide acid oligomers derived from 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 4,4'-oxydiphthalic anhydride (ODPA), pyromellitic dianhydride (PMDA), were end-crosslinked with trifunctional amine, 1,3,5-tris(4-aminophenyl)benzene (TAPB). In the case of PAA(OAA(6FDA/DAA)(4/3)-ν-TAPB) gels, SMILS has revealed that mesh size change due to the photoisomerization of azobenzene from nanoscopically trans-form to cis-form amounts to be from 2.1 to 0.83 nm, and corresponds to the change in molecular length of azobenzene upon photo-irradiation. Moreover, it was found macroscopically that this poly(amide acid) gel in a rod shape with a 0.2 mm diameter can be deflected quickly and sharply by blue laser irradiation and becomes straight reversibly by visible light irradiation. This photo-induced macroscopic bending of isotropic polymer gel rods was realized by introducing rigid aromatic rings into main chains of the polymer network. Novel flexible nano actuator for peristaltic motion induced by photoirradiation was developed by fabricating poly(amide acid) tube.