Hydrogels are soft materials that have found multiple applications in biomedicine and represent a good platform for the introduction of molecular switches and synthetic machines into macromolecular networks. Tuning their mechanical properties reversibly with light is appealing for a variety of advanced applications and has been demonstrated in the past; however, their activation typically requires the use of UV light, which displays several drawbacks related to its damaging character and limited penetration in tissues and materials. This study circumvents this limitation by introducing all‐visible ortho‐fluoroazobenzene switches into a hydrophilic network, which, as a result, can be activated with green or blue light. Photoisomerization of the photochromic moieties is accompanied by a reversible tuning of the elastic modulus. The translation of molecular isomerization within the network into macroscopic modulation of its mechanical properties is attributed to different aggregation tendencies of the E and Z isomers of the azobenzene derivatives.

中文翻译：

---

绿光和蓝光可逆地调节含氟偶氮苯的水凝胶的弹性

水凝胶是在生物医学中有多种应用的柔软材料，是将分子开关和合成机引入大分子网络的良好平台。用光可逆地调节其机械性能吸引了许多高级应用，并且在过去已得到证明。然而，它们的活化通常需要使用紫外线，这显示出与紫外线的破坏特性以及在组织和材料中的渗透受限有关的若干缺点。本研究通过引入全可见邻位来规避此限制-氟偶氮苯切换成亲水网络，因此可以用绿光或蓝光激活。光致变色部分的光异构化伴随着弹性模量的可逆调节。网络内分子异构化对其机械性能的宏观调节的转化归因于偶氮苯衍生物的E和Z异构体的不同聚集趋势。