Modular Synthesis and Patterning of High-Stiffness Networks by Postpolymerization Functionalization with Iron–Catechol Complexes

Abstract

Bioinspired iron–catechol cross-links have shown remarkable success in increasing the mechanical properties of polymer networks, in part due to clustering of Fe3+–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 Fe3+–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.

Study on Temperature-Controlled Branching Behavior with Self-Condensing Atom Transfer Radical Copolymerization of Latent Inimer and Styrene

“…where S b and S d represent the area integration values of the peaks labeled b and d in 1 H NMR, respectively (Figure 6a). As shown in Figure 6b, the detachment rate of furan varies greatly with temperatures.…”

“…Polymer science has advanced significantly through the invention of molecular constructs with functional applications. , The chemical community is focusing on the development of novel methodologies for producing polymers with complex topological structures, such as cycle polymers, polymer brushes, single-chain nanoparticles, helical polymers, etc. It has been proven that such complex chain architectures may give rise to unusual or unexpected properties of materials.…”

Macromolecular Metamorphosis in a Polymer Network via the Reversible Collapse of Single-Chain Nanoparticles

“…Polymer networks (PNs) consists of smaller components, known as “cross-links” and “strands,” that are linked together via covalent or noncovalent/supramolecular interactions. − They are universal, essential, and widely used materials that have been extensively studied and include supramolecular networks, , nanoparticle gels, and metal–organic framework networks . While these networks have been widely studied, there are still numerous challenges that require further attention to acquire a complete understanding of these networks.…”

Interfacial Fabrication of Supramolecular Polymer Networks Using Mussel-Inspired Catechol–Iron Complexes

“…Dynamic catechol–iron chemistry is correlated to the hardness and high extensibility of the cuticle of mussel byssal threads and suggested to impart self-healing properties. − The stability constants of tris- and bis-catechol–Fe 3+ complexes are among the highest values of metal–ligand chelates, and the catechol–Fe 3+ coordination can respond to different stimuli. − Using catechol–Fe 3+ complexes as cross-linkers, dynamic cross-linked polymer networks, including hydrogels and bulk systems, have been developed that exhibit excellent mechanical, self-healing, and responsive properties. − Inspired by the remarkable features of catechol–Fe 3+ complexes, it is highly desirable to design and construct catechol–Fe 3+ complex-based supramolecular polymers at the liquid–liquid interface, where the multiple stimuli-responsiveness and excellent mechanical properties are expected to be integrated.…”