Thi Vo

Acidic CO2 electroreduction in membrane electrode assemblies suppresses parasitic carbonate formation and improves carbon utilization. Yet, practical implementations remain hindered by proton accumulation and alkali cation buildup that give rise to failure modes associated with hydrogen evolution, salt precipitation, and catalyst flooding. Here, we report a multiscale interfacial design for gas diffusion electrodes that addresses these challenges across multiple length scales. Our design employs a multilayer architecture in which a microscale hydrophobic porous silica overlayer sits below a nanoscale quaternary ammonium polyelectrolyte coating. The former regulates electrolyte intrusion via capillary pressure while the latter electrostatically restricts cation accumulation. Incorporation of a hydrophilic macromolecular component into the polyelectrolyte further induces complexation-driven charge densification while simultaneously establishing percolating water channels that enhance interfacial hydration and reduce cell voltage. Our design provides CO Faradaic efficiencies of 99% sustained over 162 h, with single-pass CO2 conversion efficiency of 77% at 200 mA cm–2, on a model Ag catalyst. Furthermore, we show that the design readily generalizes across catalyst platforms and translates to scale, delivering stable operation in a 25 cm2 electrolyzer with CO production rates of ∼62 mL min–1. Lastly, techno-economic analysis projects a pathway to cost-competitive CO production, highlighting hierarchical interfacial engineering as an effective strategy for acidic CO2 electrolysis at industrially relevant scales.

Directing macromolecular organization into spatially and orientationally defined nanostructures presents a grand challenge for bottom-up materials engineering. Common approaches borrow from protein design to create foldamers (folding oligomers), wherein information about desired morphology is programmed directly into its molecular sequence. However, due to their sequence-specific synthesis requirements, state-of-the-art approaches are mostly constrained to be oligomeric in nature. Along the same vein, directed folding of polymeric macromolecules via hydrophobic collapse serves as a promising alternative, but are mostly limited to globular structures with close-packed, amorphous internal ordering. Here, we present a polymer design that blends foldameric and hydrophobic features. Our polymer architecture consists of alternating helical foldamer and flexible oligomeric domains. Such an approach leverages rigid helical domains as steric barriers to suppress globular collapse of the flexible hydrophobic blocks, thereby directing chain folding into porous nanostructures exhibiting a diverse suite of polygonal geometries. Through a combination of scaling theory and molecular dynamics simulations, we show that the resulting size, shape, and pore cavity of the folded nanostructures can be a priori designed via tuning the lengths, rather than sequence, of the foldamer and/or flexible oligomeric domains. Furthermore, we show that the folded structures possess emergent intra-chain interactions at higher densities that drive multi-chain organization into crystalline configurations with spatially and orientationally defined pore distributions. We envision that controlled polymer self-assembly into this rich landscape of open, low-coordination morphologies will present new avenues for precision engineering of soft materials with applications spanning sensing, catalysis, separations, and adaptive devices.

Steroids, specifically bile salts and corticosteroids, treat bile synthesis disorders, liver dysfunction, and inflammation. However, these water-soluble steroid drugs are rapidly cleared from the desired sites of action in the body, necessitating multiple doses. Therefore, the development of particle-based steroid medications that offer elongated therapeutic activity is of paramount medical importance. Accordingly, steroid microparticles were developed via three fabrication processes in this work, where a metal or an organic acid facilitates steroid microparticle formation. Particles fabricated using these methods exhibit consistent shape, size, and crystallinity. Furthermore, results from our coarse-grained computational model show that hydrogen bonding dictates steroid monomer-monomer interactions that determine overall particle shape and size. In addition, we demonstrate the ability to induce steroid particle formation and tune the morphology of steroid drug particles by replacing the C21 side group (tail) with chemical analogs. Thus, this study opens opportunities for the clinical translation of particle-based steroid therapeutics as an alternative to the current steroid drug formulations.

Supramolecular self-assembly of conjugated amphiphiles is governed by the interplay between enthalpic attraction from π–π interactions and entropic penalties from geometry-mediated steric repulsions.

Superlattices of polyhedral nanocrystals exhibit emergent properties defined by their structural arrangements, but native nanocrystal ligands often limit their programmability. Polymeric ligands address this limitation by enabling tunable nanocrystal softness through modifications of polymer molecular weight and grafting density. Here, we investigate phase transitions in polymer-grafted nanooctahedra by varying polymer length, nanocrystal size, truncation, and ligand density. In two-dimensional superlattices, longer polymers or smaller nanooctahedra induce a transition from orientationally ordered to hexagonal rotator lattices. In three-dimensional superlattices, increasing polymer length drives transitions from Minkowski to body-centered cubic and plastic hexagonal close-packed phases, while higher grafting densities further enable transitions to simple hexagonal phases. Polymer brush and thermodynamic perturbation theories, supported by Monte Carlo simulations, uncover the entropic and enthalpic forces that govern these transitions. This work highlights the versatility of polymer-grafted anisotropic nanocrystals as building blocks for designing hierarchical superstructures and metamaterials with customizable properties.

Advances in experimental synthesis and computer simulations have led to the proliferation of anisotropy and particle geometry as popular handles for directed self-assembly. This paradigm employs entropy to direct building block organization into desired spatial and orientational orderings. Yet, how does a metric associated primarily with disorder give rise to ordered assemblies? We first explain the governing principles behind entropic crystallization and entropy maximization processes. We then show how entropic forces can produce emergent, attractive, and bond-like interactions between otherwise sterically repulsive particles. Building on these ideas, we establish entropy as a mediator of interparticle attraction in hard particle systems that relies on extrinsic, systems-level behaviors as opposed to intrinsic, particle-level properties. Finally, we present a theory of entropic bonding that formalizes the phenomena discussed into a rigorous mathematical framework and discuss relevant next steps for its development and applications of entropic crystallization in materials design.

Selective nanoparticle surface patterning presents incredible promise for broadening programmable materials design into a space beyond “close-packed” morphologies. These “patchy” particles impose directional attractions between neighbors that favor the formation of low-coordination, open structures previously inaccessible via their isotropically interacting nanoparticle counterparts. However, unlike patchy colloids, patches on nanoparticles are highly deformable, presenting challenges for their predictive design. Here, we present a multi-faceted approach combining theory and simulation to investigate the underlying forces governing interactions between nanoparticles with flexible patches. We first develop a thermodynamic perturbation theory to fundamentally capture the interplay between patch–patch merging and directional entropic forces in controlling particle organization. We then employ theoretical insights to explicitly consider how monomer geometry synergizes with monomer connectivity in sculpting the equilibrium morphologies for polymeric chains composed of anisotropic monomeric subunits. Theory predictions are then validated using simulations, with excellent agreement across both local and global length scales. Combined, our findings indicate that a large suite of orientational and structural diversity can be attained via precision engineering of how patch–patch and entropic forces between the anisotropic nanoparticles counterbalance each other. These findings on nanoscale patchy interactions offer newer avenues for directing the assembly process of novel polymeric and metamaterials.

Effectively utilizing MEK inhibitors in the clinic remains challenging due to off-target toxicity and lack of predictive biomarkers. Recent findings propose E-cadherin, a breast cancer diagnostic indicator, as a predictor of MEK inhibitor success. To address MEK inhibitor toxicity, traditional methodologies have systemically delivered nanoparticles, which require frequent, high-dose injections. Here, we present a different approach, employing a thermosensitive, biodegradable hydrogel with functionalized liposomes for local, sustained release of MEK inhibitor PD0325901 and doxorubicin. The poly(δ-valerolactone-co-lactide)-b-poly(ethylene-glycol)-b-poly(δ-valerolactone-co-lactide) triblock co-polymer gels at physiological temperature and has an optimal degradation time in vivo. Liposomes were functionalized with PR_b, a biomimetic peptide targeting the α₅β₁ integrin receptor, which is overexpressed in E-cadherin-positive triple negative breast cancer (TNBC). In various TNBC models, the hydrogel-liposome system delivered via local injection reduced tumor progression and improved animal survival without toxic side effects. Our work presents the first demonstration of local, sustained delivery of MEK inhibitors to E-cadherin-positive tumors alongside traditional chemotherapeutics, offering a safe and promising therapeutic strategy.

Synthesizing reconfigurable nanoscale synthons with predictive control over shape, size, and interparticle interactions is a holy grail of bottom-up self-assembly.