Shannon Declan P, Moon Joshua D, Barney Christopher W, Sinha Nairiti J, Yang Kai-Chieh, Jones Seamus D, Garcia Ronnie V, Helgeson Matthew E, Segalman Rachel A, Valentine Megan T, Hawker Craig J
Materials Department, University of California Santa Barbara, Santa Barbara, California 93106-5050, United States.
Materials Research Laboratory, University of California Santa Barbara, Santa Barbara, California 93106-5121, United States.
Macromolecules. 2023 Mar 15;56(6):2268-2276. doi: 10.1021/acs.macromol.2c02561. eCollection 2023 Mar 28.
Bioinspired iron-catechol cross-links have shown remarkable success in increasing the mechanical properties of polymer networks, in part due to clustering of Fe-catechol domains which act as secondary network reinforcing sites. We report a versatile synthetic procedure to prepare modular PEG-acrylate networks with independently tunable covalent bis(acrylate) and supramolecular Fe-catechol cross-linking. Initial control of network structure is achieved through radical polymerization and cross-linking, followed by postpolymerization incorporation of catechol units via quantitative active ester chemistry and subsequent complexation with iron salts. By tuning the ratio of each building block, dual cross-linked networks reinforced by clustered iron-catechol domains are prepared and exhibit a wide range of properties (Young's moduli up to ∼245 MPa), well beyond the values achieved through purely covalent cross-linking. This stepwise approach to mixed covalent and metal-ligand cross-linked networks also permits local patterning of PEG-based films through masking techniques forming distinct hard, soft, and gradient regions.
受生物启发的铁 - 儿茶酚交联在提高聚合物网络的机械性能方面已取得显著成功，部分原因是作为二级网络增强位点的铁 - 儿茶酚域的聚集。我们报告了一种通用的合成方法，用于制备具有独立可调共价双（丙烯酸酯）和超分子铁 - 儿茶酚交联的模块化聚乙二醇 - 丙烯酸酯网络。通过自由基聚合和交联实现对网络结构的初步控制，随后通过定量活性酯化学将儿茶酚单元进行后聚合引入，并随后与铁盐络合。通过调整每个构建块的比例，制备了由聚集的铁 - 儿茶酚域增强的双交联网络，其表现出广泛的性能（杨氏模量高达约245 MPa），远远超出了通过纯共价交联所达到的值。这种混合共价和金属 - 配体交联网络的逐步方法还允许通过掩膜技术对基于聚乙二醇的薄膜进行局部图案化，形成不同的硬、软和梯度区域。
