Abstract It is still difficult to precisely control microscopic wrinkles on the surface of functional materials, especially biomimetic soft hydrogels with an elastic modulus lower than 100 kPa. This is due to the difficulty in realizing the systematic and independent regulation of elasticity on the top surface and in the bulk of hydrogels, which is essential for the generation of surface microwrinkles. To overcome this problem, using a two-step photocrosslinking process with VIS and UV irradiation of a photocurable gelatinous sol, we developed a method for independently regulating the elastic modulus on the surface and in the bulk to obtain wrinkles on a biomimetic soft gel. Photocurable gelatin was first irradiated and crosslinked with VIS light in the presence of the water-soluble radical generator sulfonyl camphorquinone, which is effective in forming thick bulk gels. Next, the top surface of these precrosslinked gels was irradiated with UV light in the presence of surface-coated water-insoluble camphorquinone. As a result, this two-step photocrosslinking process enabled to independently control the elastic moduli of the surface and the bulk lower than 100 kPa and to generate several-micron-scale wrinkles on the soft hydrogel surface. To precisely design microwrinkles on a biomimetic hydrogel, a two-step photocrosslinking process with VIS and UV irradiation was developed. Photocurable gelatin was first crosslinked with VIS light in the presence of the water-soluble radical generator to form thick bulk gels. Next, the top surface of the gels was irradiated with UV light in the presence of surface-coated water-insoluble radical generator. This two-step photocrosslinking process enabled to independently control the elastic moduli of the surface and the bulk lower than 100 kPa and to generate several-micron-scale wrinkles on the soft hydrogels.

中文翻译：

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通过独立调节表面和软水凝胶主体中的弹性来精确设计微皱纹

摘要 功能材料尤其是弹性模量低于100 kPa的仿生软水凝胶表面的微观皱纹仍然难以精确控制。这是由于难以在顶部表面和大部分水凝胶中实现系统和独立的弹性调节，这对于表面微皱纹的产生至关重要。为了克服这个问题，我们使用可见光和紫外光照射可光固化凝胶溶胶的两步光交联过程，开发了一种独立调节表面和本体弹性模量的方法，从而在仿生软凝胶上获得皱纹。光固化明胶首先在水溶性自由基产生剂磺酰樟脑醌存在下用可见光照射并交联，这对于形成厚的散装凝胶是有效的。接下来，在表面涂覆的水不溶性樟脑醌存在下，用紫外光照射这些预交联凝胶的顶面。因此，这种两步光交联过程能够独立控制表面的弹性模量和体积低于 100 kPa，并在软水凝胶表面产生几微米级的皱纹。为了在仿生水凝胶上精确设计微皱纹，开发了一种具有可见光和紫外线照射的两步光交联工艺。光固化明胶首先在水溶性自由基产生剂的存在下用可见光交联，形成厚厚的凝胶。接下来，在表面涂覆的水不溶性自由基产生剂的存在下，用紫外光照射凝胶的顶面。