We present a versatile one-pot synthesis method for creating surface-anchored orthogonal gradient networks using a small bi-functional gelator, 4-azidosulfonylphenethyltrimethoxysilane (4-ASPTMS). The sulfonyl azide (SAz) group of 4-ASPTMS is UV (≤254 nm) and thermally active (≥100 °C) and, thus, enables us to vary the cross-link density in orthogonal directions by controlling the activation of SAz groups via UV and temperature means. We deposit a thin layer (∼200 nm) of a mixture comprising ∼90% precursor polymer and ∼10% 4-ASPTMS in a silicon wafer. Upon UV irradiation or annealing the layers, SAz releases nitrogen by forming singlet and triplet nitrenes that concurrently react with any C–H bond in the vicinity leading to sulfonamide cross-links. Condensation among trimethoxy groups in the bulk connects 4-ASPTMS units and completes the cross-linking. Simultaneously, 4-ASPTMS near the substrate reacts with surface-bound –OH motifs that anchor the cross-linked polymer chains to the substrate. We demonstrate the generation of orthogonal gradient network coatings exhibiting cross-link density (or stiffness) gradients in orthogonal directions using such a simple process.

中文翻译：

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用于创建梯度聚合物网络涂层的紫外线和热活性小型双功能胶凝剂

我们提出了一种通用的单锅合成方法，使用小型双功能胶凝剂 4-叠氮磺酰基苯乙基三甲氧基硅烷 (4-ASPTMS) 创建表面锚定的正交梯度网络。4-ASPTMS 的磺酰叠氮化物 (SAz) 基团具有紫外线 (≤254 nm) 和热活性 (≥100 °C)，因此，使我们能够通过控制 SAz 基团的激活来改变正交方向的交联密度通过紫外线和温度手段。我们在硅晶片中沉积了一层薄薄的混合物（~200 nm），该混合物包含~90% 的前体聚合物和~10% 的 4-ASPTMS。在紫外线照射或退火层后，SAz 通过形成单线态和三线态氮烯释放氮，这些氮烯同时与附近的任何 C-H 键反应，导致磺酰胺交联。主体中三甲氧基之间的缩合连接 4-ASPTMS 单元并完成交联。同时，底物附近的 4-ASPTMS 与表面结合的 –OH 基序发生反应，这些基序将交联的聚合物链固定在底物上。我们演示了使用这样一个简单的过程在正交方向上展示交联密度（或刚度）梯度的正交梯度网络涂层的生成。