Membranes are a critical component of redox flow batteries (RFBs), and their major purpose is to keep the redox-active species in the two half cells separate and allow the passage of chargebalancing ions. Despite significant performance enhancements in RFB membranes, further developments are still needed that holistically consider conductivity, selectivity, stability, sustainability, and cost. In this Focus Review, structure−property relationships that have led to advances in membranes for various RFB types (vanadium, zinc, iron, etc.) are analyzed. First, two strategies to increase conductivity are highlighted: tuning membrane microstructure and controlling electrolyte uptake. Next, selectivity improvements through size and/or Donnan exclusion are reviewed. With respect to stability, methods to enhance the mechanical robustness of membranes and factors that affect chemical stability are discussed. Additionally, avenues to reduce battery cost and increase sustainability are explored. Future directions are suggested, which include how more in-depth theoretical studies, microstructure optimization, and enhanced characterization will push the field of RFB membranes forward.

Serving as a decades old answer to synthetic proteins, polypeptides possess beneficial chemical and mechanical characteristics as well as secondary structure that can lead to the formation of complex nanostructures. Utilizing these characteristics, scientists have strived toward developing "smart" materials to aid in drug delivery, wound healing, and tissue engineering. In this Perspective, we discuss some aspects of the current state of oligopeptide and polypeptide research and highlight important fields relating to the self-assembly of traditional polypeptides, peptide amphiphiles, hydrogels, protein−polypeptide conjugates, and multiarm or branched systems. This Perspective serves to highlight the recent (2015−present) advances in block oligo/polypeptides, specifically self-assembly of NCA-derived polypeptides, peptide amphiphiles, hydrogels, protein conjugation, and dendrimer/ star polymers. Our primary focus is to outline the importance of oligo/polypeptide structure and nanoarchitecture and how these parameters dictate self-assembly and/or function.

A soybean based coating with thermally responsive Diels-Alder linkages has been prepared following an automotive 2-component formulation. The resulting coatings displayed the capability to be healed following physical deformation by a thermal stimulus, and such a material has significant potential for end users. Various curing agents were employed, and resulted in variation of scratch resistance and re-healablity. Different thermally responsive soybean resins were synthesized to have varying amounts reversible and nonreversible linkages when incorporated into the coating. Additionally, different isocyanates were added at differing ratios of NCO : OH in search of the optimum coating. It was found through the analysis of rehealability, hardness, gloss, and adhesion that the optimal combination was an acetylated resin (no irreversible crosslinks) with 54% reversible Diels-Alder linkages at an NCO : OH ratio of 5 : 1 using isophorone diiscocyanate. Materials were evaluated via differential scanning calorimetry (DSC), scratch resistance, Koenig hardness, gloss measurements, and topographical analysis.

Using Diels–Alders (DA) chemistry as a dynamic-covalent linkage, we explored the kinetic growth mechanism of polymer structures including starlike materials and nanogels. The use of reversible addition–fragmentation chain transfer (RAFT) polymerization allows for precise control of DA linkages within the polymer backbone. Controlling the competition between intra- and intermolecular cross-linking reactions allows for the preparation of polymer structures that can expand their volume after cleavage of the DA linkages as determined by dynamic light scattering (DLS). Macroscopically, this would be analogous to untying a rope ball knot, commonly termed a “monkey’s fist”.