Laurano Rossella, Boffito Monica, Cassino Claudio, Midei Ludovica, Pappalardo Roberta, Chiono Valeria, Ciardelli Gianluca
Department of Mechanical and Aerospace Engineering, Politecnico di Torino, 10129 Turin, Italy.
Department of Science and Technological Innovation, Università del Piemonte Orientale, 15121 Alessandria, Italy.
Materials (Basel). 2023 Feb 28;16(5):2024. doi: 10.3390/ma16052024.
Temperature and light responsiveness are widely exploited stimuli to tune the physico-chemical properties of double network hydrogels. In this work, new amphiphilic poly(ether urethane)s bearing photo-sensitive moieties (i.e., thiol, acrylate and norbornene functionalities) were engineered by exploiting the versatility of poly(urethane) chemistry and carbodiimide-mediated green functionalization procedures. Polymers were synthesized according to optimized protocols maximizing photo-sensitive group grafting while preserving their functionality (approx. 1.0 × 10, 2.6 × 10 and 8.1 × 10 thiol, acrylate and norbornene groups/g), and exploited to prepare thermo- and Vis-light-responsive thiol-ene photo-click hydrogels (18% /, 1:1 thiol:ene molar ratio). Green light-induced photo-curing allowed the achievement of a much more developed gel state with improved resistance to deformation ( 60% increase in critical deformation, γL). Triethanolamine addition as co-initiator to thiol-acrylate hydrogels improved the photo-click reaction (i.e., achievement of a better-developed gel state). Differently, L-tyrosine addition to thiol-norbornene solutions slightly hindered cross-linking, resulting in less developed gels with worse mechanical performances (~62% γL decrease). In their optimized composition, thiol-norbornene formulations resulted in prevalent elastic behavior at lower frequency compared to thiol-acrylate gels due to the formation of purely bio-orthogonal instead of heterogeneous gel networks. Our findings highlight that exploiting the same thiol-ene photo-click chemistry, a fine tuning of the gel properties is possible by reacting specific functional groups.
温度和光响应性是广泛用于调节双网络水凝胶物理化学性质的刺激因素。在这项工作中，通过利用聚氨酯化学的多功能性和碳二亚胺介导的绿色功能化程序，设计了带有光敏部分（即硫醇、丙烯酸酯和降冰片烯官能团）的新型两亲性聚（醚-聚氨酯）。根据优化方案合成聚合物，在保留其功能的同时最大限度地提高光敏基团接枝率（约1.0×10、2.6×10和8.1×10个硫醇、丙烯酸酯和降冰片烯基团/克），并用于制备热响应和可见光响应的硫醇-烯光点击水凝胶（18% /，硫醇:烯摩尔比为1:1）。绿光诱导的光固化能够实现更发达的凝胶状态，同时提高抗变形能力（临界变形γL增加60%）。添加三乙醇胺作为硫醇-丙烯酸酯水凝胶的共引发剂可改善光点击反应（即实现更发达的凝胶状态）。不同的是，向硫醇-降冰片烯溶液中添加L-酪氨酸会略微阻碍交联，导致凝胶发育较差且机械性能更差（γL降低约62%）。在其优化组成中，由于形成了纯生物正交而非异质的凝胶网络，硫醇-降冰片烯配方在较低频率下比硫醇-丙烯酸酯凝胶表现出更普遍的弹性行为。我们的研究结果表明，利用相同的硫醇-烯光点击化学，通过使特定官能团反应可以对凝胶性质进行微调。
