Phase separation plays a crucial role in toughening hydrogels. Thus, regulating the phase-separation structure is vital to understanding the toughening mechanism in phase-separated hydrogels. Current synthesis strategies often provide limited control on phase-separated structures. In this work, a library of short-alkyl-side-chain-modified hydrogels is fabricated as model phase-separated hydrogels to investigate the length effects of short alkyl side chains on the phase-separated structure, apparent mechanics, and dynamics. Short-alkyl-chain-modified polymers undergo vapor-induced phase separation from highly concentrated solutions and coalesce into a well-connected polymer-rich phase. With increasing length of the side chains, the polymer-rich domain thickens due to enhanced hydrophobic interaction. Rheology suggests that longer alkyl side chains result in higher “glass”-transition temperatures and slower dynamics. However, by correlating the stretch rate and temperature dependence of both the small deformation properties (linear rheology) and the large deformation properties (tensile behavior), we find that regardless of the length of the side chain, hydrogels become tough and strong when the tensile test temperature approaches the glass-transition temperature or the stretch rate matches the relaxation time in the intermediate frequency regime. The strength and toughness of the gels obtained in this work are the combined effect of phase separation and glass transition. This work sheds light on the design principles for the mechanical elements in phase-separated hydrogels.

Natural gels are constrained by a limited number of building blocks, yet based on time and space organization, they perform diverse functions. In contrast, the properties of synthetic hydrogels are frequently tuned through substantial changes in their chemical make-up, causing complex interplay between composition, structure, and properties. This work fabricates a series of hydrogels with identical compositions but disparate properties by selectively quenching the depth and path of a water vapor-induced phase separation process. These hydrogels are solely comprised of short alkyl side-modified polyvinyl alcohol at the same volume fraction, but they exhibit hierarchical differences across multiple length scales, including porous morphology (≈µm), hydrophobic clusters (≈10 nm), and molecular packing (subnm). The hierarchical discrepancy is explicitly related to the striking contrast in terms of turbidity, permeability, stretchability, and viscoelasticity, thus advancing the understanding of the relationship between multiscale structures and properties without interference from chemical formulations. In addition, the hydrogels exhibit excellent biocompatibility, acid-aided degradability, in situ healability, and underwater malleability. This work exploits a design principle to imitate the hierarchically specific tenet in nature, that is, the spatiotemporal organization of a single type of polymer via kinetic arrest of network-forming phase separation, rather than modulation of the chemical make-ups.

Severe Zn dendrite growth and side reactions greatly limit the application of aqueous zinc-ion batteries. Herein, we design a layer of polyionic liquid (PCAVImBr) film with a tunable pore size and charge density on the Zn anode to endow homogenized distribution of an electronic field, acerated Zn2+ permeation, and inhabitation of water entry. Such an optimal combination is achieved via a polymerization induced phase separation strategy, where the enhanced cross-linking density arrests the phase separation in a shallow depth and vice versa. Furthermore, the Zn@PCAVImBr electrode has good plating/stripping reversibility, which retains a 99.6% CE efficiency after 3000 cycles. The symmetric cells can achieve a cycle life of more than 2400 h at different current densities. It is worth mentioning that the NVO//Zn@PCAVImBr full cell can still reach a 91.2% capacity retention after nearly 4000 cycles at a high current of 10 A g–1, and provides new insights for the future research of zinc-ion battery anodes.

A series of polystyrene sulfonate threaded in MIL-101Cr(iii) composites both with and without cross-linkers were synthesized. These composites demonstrated superior activity and durability for the acid catalyzed reaction, thus highlighting the importance of surface properties, mobility and accessibility of active sites in determining the catalytic performance.

but donor cornea is scarce, [2] leading to delayed intervention and an increased probability of visual loss. [3] Furthermore, many patients cannot tolerate the donor cornea owing to repeated graft failure, autoimmune diseases, and ethical reservations. [4] To address these issues, effort has been devoted to exploring potential artificial corneas (keratoprostheses). [2] The prevailing keratoprosthesis approaches are either a pre-made synthetic prosthesis for restoring vision or a tissue-engineering scaffold for generating new tissue in situ. [5] Although tissue-engineered keratoprostheses can effectively regenerate the damaged cornea tissues, it is not free of ethical conundrums, and the immune rejection of the matrix's natural or artificial and donated cells can occur. [4b,6] In contrast, the completely synthetic cornea substitutes are merely constructed by synthetic materials, and thus overcome both sociocultural and policy difficulties in addition to avoiding viral invasion and immune rejection, [5,7,8] From the perspective of materials science, an optimal substrate for a synthetic cornea should combine vital features (Figure 1a) such as transparency for vision, processability for personalized geometry and size, [9] permeability for oxygen and nutrient transportation, and robustness to withstand the mechanical and environmental Corneal transplantation is impeded by donor shortages, immune rejection, and ethical reservations. Pre-made cornea prostheses (keratoprostheses) offer a proven option to alleviate these issues. Ideal keratoprostheses must possess optical clarity and mechanical robustness, but also high permeability, processability, and recyclability. Here, it is shown that rationally controlling the extent of arrested phase separation can lead to optimized multiscale structure that reconciles permeability and transparency, a previously conflicting goal by common pore-forming strategies. The process is simply accomplished by hydrothermally treating a dense and transparent hydrophobic association hydrogel. The examination of multiscale structure evolution during hydrothermal treatment reveals that the phase separation with upper miscibility gap evolves to confer time-dependent pore growth due to slow dynamics of polymer-rich phase which is close to vitrification. Such a process can render a combination of multiple desired properties that equal or surpass those of the state-of-the-art keratoprostheses. In vivo tests confirm that the keratoprosthesis can effectively repair corneal perforation and restore a transparent cornea with treatment outcomes akin to that of allo-keratoplasty. The keratoprosthesis is easy to access and convenient to carry, and thus would be an effective temporary substitute for a corneal allograft in emergency conditions.