Concentrated hydrogen-bonded electrolytes (CoHBEs) are structured, electrochemically stable, less-volatile alternatives to aqueous and dilute nonaqueous electrolytes, however, with high viscosities that limit molecular diffusion. This work provides an understanding of the proton conduction mechanism in CoHBEs based on mixtures of acids and azoles and establishes a link between the structurally dictated transport properties and the proton-coupled electron transfer (PCET) reaction rates that can be leveraged for enhancing electrochemical reactions. Diffusion and relaxation NMR studies suggest a breaking of the viscosity-conductivity tradeoff, where at high azole concentrations (>45 mol%), Grotthuss transport is more likely with lowered proton transfer energy barriers between the azole and the acid according to the machine learning (ML) accelerated ab initio path integral MD (AI-PIMD) simulations. Proton conduction pathways are found to be switchable between the hydrogen bonding networks of the acid and the azole, with imidazole chain forming structures better facilitating Grotthuss hopping. Supported by small-angle neutron scattering studies, the chains are found to have six member molecules on average with maximum of 3 to 4 imidazole/imidazoliums at 50 to 60 mol%. Despite their high viscosities, the measured PCET rates for quinones and phenazines measured in the protic CoHBEs present relatively high electron transfer rate constants (k0 ~ 10-4 cm/s), validated by rotating disc electrode and scanning electrochemical microscopy measurements. The results demonstrate that strategic tuning of hydrogen-bond donor-acceptor interactions enables the decoupling of proton transport and viscosity, thereby impacting PCET reactions.

ABSTRACT Polymer powder bed fusion (PBF/P) is an additive manufacturing technology that fabricates end‐use products for many applications. Thermal‐induced phase separation (TIPS) has been adapted to produce spherical isotactic polypropylene (PP) powders suitable for PBF/P. In this study, the evolution of the i‐ PP crystalline structure is tracked as the material evolves from the as‐received pellets to TIPS produced powders to PBF/P printed parts in i ‐PP molecular‐weight blends. TIPS‐produced powders show composition‐dependent lamellar structures: long periods in the powder MW blends are larger than those in the pellets when the 12k i‐ PP composition is < 10% or > 33%, but similar to those in the 12k i‐ PP pellet when the 12k composition is 10%–33%. This is attributed to entropically driven surface enrichment of 12k chain and their early crystallization in the powder particles of blends between 10% and 33% 12k i‐ PP. Outside of this composition range, the larger molecular weight i‐ PP dominates the crystallization. In contrast, printed parts exhibit similar long periods across all blend compositions, suggesting that an energy density of the laser fully melts the crystals, which erases the thermal history of the blends. These results demonstrate the utility of scattering methods to guide the rational design of novel PBF/P feedstocks.

This study presents a closed-loop recycling strategy for post-consumer polyethylene terephthalate (PET) that avoids complete depolymerization to monomers, rather, demonstrating that controlled glycolysis to oligomers is sufficient for high-quality material recovery. Using a 1:1 triazabicyclodecene (TBD):methanesulfonic acid (MSA) catalyst and ethylene glycol (EG) at 180 °C, PET bottles were partially depolymerized to obtain uniform oligomeric products (Mn: 6.1 kDa; Mv: 9.8 kDa) rather than monomers, circumventing the need for harsh reaction conditions and complex purification steps. The repolymerization of these oligomers during solid-state polymerization (SSP) at 240 °C under vacuum was monitored to assess molecular weight recovery and the influence of retained species on reaction progress. Viscosity measurements reveal substantial chain growth, with viscosity-average molecular weights (Mv) reaching over 80% of virgin PET after 26 h of SSP. Gas chromatography-mass spectrometry (GC–MS) analysis indicates that additives and low-molecular-weight by-products persist through depolymerization and influence SSP kinetics, acting as both facilitators and inhibitors depending on their volatility and reactivity. Swelling experiments further demonstrate that pre-annealing treatments effectively reduce residual ethylene glycol, improving chain extension efficiency. Mechanical testing confirms that repolymerized PET recovers tensile properties comparable to virgin material. These results demonstrate that controlled oligomeric intermediates, rather than monomeric species, can serve as effective precursors for molecular weight regeneration. These findings challenge the conventional assumption that complete depolymerization to monomers is required for effective polymer recycling. More broadly, this work highlights the importance of oligomer distribution, additive retention, and phase behavior in governing degradation-repolymerization pathways, providing insight into more efficient and practical routes for polymer recycling.

Recycling polyolefins is a growing concern as these materials make up approximately 50% of plastic waste. This research focuses on elucidating the relationship between monomer sequence distribution of commercially available ethylene-propylene random copolymers and an ethylene/1-olefin copolymer and its effect on compatibilizer efficiency in high-density polyethylene (HDPE)/isotactic polypropylene (i-PP) blends. The compatibilization of both HDPE-rich and i-PP-rich blends was examined to determine the impact of matrix composition on the ability of these compatibilizers to enhance the mechanical properties of the phase-separated blend. Overall, the results show that increasing the concentration of the semicrystalline ethylene content and ethylene-ethylene-ethylene triad components in the copolymer compatibilizer improved the tensile toughness of both blends. The toughness of the HDPE-rich blend was improved by a maximum factor of 20, while the toughness of the i-PP-rich blend doubled in the presence of 5 wt% compatibilizer loading. These findings indicate that the compatibilization of these blends with random copolymers is entanglement-dependent; however, the presence of semicrystalline segments can greatly increase the compatibilizer efficiency. Additionally, ethylene-1-olefin copolymers appear to improve the toughness of the compatibilized blends the most in the HDPE-rich blends, whereas the ethylene-propylene copolymers are the most effective compatibilizer in the i-PP-rich blends.

Chemical recycling of condensation polymers is often rationalized on the basis of the intrinsic reactivity of ester and carbonate functional groups. However, under heterogeneous conditions relevant to plastic waste processing and environmental degradation, bulk depolymerization rates often diverge from trends predicted by homogeneous chemistry. Here, we investigate how polymer-solvent compatibility, catalyst strength, and phase behavior govern the heterogeneous glycolysis of carbonyl-containing polymers. Using poly(ethylene terephthalate) (PET), glycol-modified PET (PETG), and bisphenol-A polycarbonate (PC) as model systems, we examine depolymerization kinetics at 180 degrees C with ethylene glycol and bisphenol A as diols under both amphoteric organosalt (TBD : MSA) and strong base (TBD) catalysis. Despite substantial differences in crystallinity and glycol uptake, PET and PETG depolymerize at comparable rates under organosalt catalysis, while PC depolymerizes significantly more slowly under identical conditions. Time-resolved molecular weight analysis and thermal characterization demonstrate that these rate differences do not arise from crystallinity, swelling, or inherent carbonyl reactivity, but instead reflect solubility-limited kinetics that constrain the transition from heterogeneous to homogeneous reaction regimes. When polymer solubility is low, depolymerization remains heterogeneous and slow; when solubility is enhanced-either through increased polymer-diol compatibility or stronger base catalysis-rapid homogeneous depolymerization is observed, reversing apparent reactivity trends. These results establish solubility and phase behavior as primary determinants of depolymerization kinetics in heterogeneous polymer recycling systems. By demonstrating how catalyst selection and solvent compatibility can expose or overcome solubility limitations, this work provides mechanistic insight to design more energy-efficient and selective chemical recycling processes. More broadly, these findings suggest that polymers with limited solvent or water compatibility may resist chemical degradation in the environment, favoring fragmentation and persistence as micro- and nanoplastics. Understanding solubility-controlled depolymerization offers a pathway toward more sustainable polymer design and end-of-life chemical recovery.

Structured electrolytes, such as those with high salt concentrations (e.g., water-in-salt), offer a versatile platform for tuning interfacial structure, electric-field effects, and reaction selectivity in electrocatalysis. In this study, we investigate a potassium-based structured electrolyte for electrochemical CO 2 reduction using a combined experimental and computational approach. Electroanalytical measurements, X-ray scattering, nuclear magnetic resonance (NMR), and molecular dynamics (MD) simulations are employed to understand the bulk versus interfacial behavior of the electrolytes. These insights are used to rationalize the enhanced formation of multi-carbon products (about 80% Faradaic Efficiency) on the copper electrode and the high CO selectivity (>90% Faradaic Efficiency) on the silver electrode during electrochemical CO 2 reduction. In particular, we observe a strong compositional dependence, indicating an ideal condition for electrocatalytic reactions. In situ surface-enhanced Raman spectroscopy (SERS), electrochemical impedance spectroscopy, and MD simulations collectively suggest an interplay among interfacial crowding, proton availability controlled by water activity, and CO 2 transport in dictating electrocatalytic reaction outcomes. This presentation will highlight key findings on the role of aqueous structured electrolytes for selective electrocatalytic reactions.

Managing the end-of-life of plastics is a challenging problem for a variety of reasons, including the complexity of recycling mixed waste streams. This is due to the inherent immiscibility of different polymers. One method to improve the properties of immiscible polymer pairs is through compatibilization. This study is designed to provide insight into the molecular mechanisms that result in the effective compatibilization of immiscible polymer blends that contain crystalline polymers, as crystalline polymers are a dominant fraction of the waste stream. In this study, the immiscible polymer pair examined contains polyvinyl chloride (PVC) and a polyolefin, as this pair of polymers is difficult to sort and make up a significant portion of commercial polymers in the waste stream. In these studies, the strength of the interface between amorphous poly(vinyl) chloride (PVC) and semicrystalline polyolefin elastomer (POE) compatibilized with chlorinated polyethylene (c-PE) are monitored as well as the strength of the interface between each homopolymer-compatibilizer pair. The results of this research show improvement in the interfacial adhesion at the c-PE/POE, c-PE/PVC and PVC/c-PE/POE interfaces as the blockiness of c-PE increases, which is interpreted to indicate that the entanglement of the compatibilizer with both the amorphous and semicrystalline phases is necessary to effectively compatibilize the biphasic interface. Further DSC, SAXS, and WAXS data provide evidence that semicrystalline compatibilizers can co-crystallize with the polyolefin elastomers, indicating that the co-crystallization can further strengthen the biphasic interface. Thus, this research provides insight into the molecular design of effective compatibilizers and the molecular level mechanisms that occur in compatibilized phase separated amorphous/crystalline polymer blends.

Neutron scattering and reflectivity are unique tools that offer insight into the ordering and structure of complex and multi-component materials on length scales from a few angstroms to 100’s of nanometers. We will discuss efforts in our group that use neutron scattering to elucidate the structure of novel electrolytes and correlate this structure to their performance. For instance. Microemulsions have been identified as a unique class of material that can be incorporated in energy storage systems (i.e. flow batteries). To correlate structure to performance, we use small-angle neutron scattering (SANS) to investigate the impact of surfactant molecular structure on the structure and properties of their oil/water microemulsions, which in turn impacts their performance in devices. More precisely, we examine the impact of the molecular structure of non-ionic surfactants on the morphology, domain size, and interfacial rigidity in water/toluene/surfactant microemulsions. In these studies, the structure and properties of water/toluene/surfactants microemulsions that contain Tween-20 and Brij-35 are determined by small angle neutron scattering. Tween-20 and Brij-35 were chosen as the are both non-ionic surfactants with similar atomic composition, but vary in their molecular structure where the Brij-35 is a linear molecule, while Tween-20 is branched. This variation in molecular topology impacts the assembly of the surfactant at the oil/water interface, which influences the rigidity of the interface and morphology of the microemulsion, which will be discussed. These structural changes are correlated to the conductivity and ion diffusion in these microemulsions. We will also present similar SANS studies that elucidate the impact of confinement to a porous carbon paper on the structure of the microemulsion. Porous carbon paper is often used as an electrode in electrochemical devices, and thus this structural variation is relevant to devices performance. The impact of surfactant molecular structure on these confinement effects is also under investigation.

Polymers are known to spontaneously produce microplastics (sizes 1 μm – 3 mm) and nanoplastics (10 nm – 1 μm). Still, the mechanisms by which environmentally-triggered Å-level random bond breaking events lead to the formation of these relatively large fragments are unclear. Significantly, $$\approx$$ 70% of commercial polymers are semicrystalline, with a morphology comprised of alternating crystalline and amorphous layers, each tens of nanometers thick. It is well-accepted that chain scission events accumulate in the amorphous phase. We show that this leads to mechanical failure and the concurrent release of particulate nanoplastics comprised of polydisperse stacks of lamellae even under quiescent conditions. Noncrystalline analogs, which do not have a well-defined microstructure, do not form nanoplastics. While the amorphous phase of the semicrystalline nanoplastics continues to degrade, crystal fragments do not, and hence, they temporally persist in the environment. These results stress the critical role of polymer microstructure and fracture mechanics on particulate nanoplastic creation. Polymers are known to spontaneously produce micro- and nanoplastics but the mechanisms by which environmentally-triggered Å-level random bond breaking events lead to the formation of these relatively large fragments are unclear. Here, the authors show that chain scission accumulates in the amorphous phase of a semicrystalline morphology which leads to mechanical failure and the concurrent release of nanoplastics even under quiescent conditions.

Plastic particles in the range of 1 nm to 1 μm in diameter are nano pollutants in all environments, ubiquitous throughout the air, all waters and living organisms. The formation of nanoplastics (NP) occurs in different ways that include material abrasion, light exposure and even from normal use of plastic materials. In solvents, NP and small microplastics (< 10 μm diameter) differ from larger plastic particles in that they can mix and suspend, similar to other colloidal sized particles. In this study, we used normal mixing conditions and our novel solubilization method to generate polyethylene (PE) small microplastic and nanoplastic solutions (sM&NP), both in water and in common organic solvents. The sM&NP were examined using Raman spectroscopy and microscopy, transmission electron microscopy (TEM) and particle size analysis using dynamic light scattering (DLS) methods. The Raman data showed notable spectral changes compared to solid PE, which indicates significant molecular and morphological changes of the PE polymer when it is part of these sM&NP solutions or suspensions. In organic solvents, the spectral changes for sM&NP signified a loss of polymer crystallinity, while the changes in aqueous solutions suggest greater molecular reorganization of the polymer structure. These structural changes were supported by TEM images of the particles that appeared mostly amorphous with varying thickness. Importantly, the changed spectra of these small particles of PE likely render them more difficult to detect and study, particularly in real-world aqueous systems. These findings indicate that solubilized sM&NP are routinely modified by solvent exposure, and thereby interact differently from larger plastic materials, particularly in aqueous environments.

The research presented in this paper offers insight into the availability of intermediates in the depolymerization of polyethylene terephthalate (PET) to be used as feedstock to create value-added products. Monitoring the dispersity, molecular weight, end groups, and crystallinity of reaction intermediates during the heterogeneous depolymerization of PET offers insight into the mechanism by which the polymer chains evolve during the reaction. Our results show dispersity decreases and crystallinity increases while the yield of insoluble PET remains high early in the reaction. Our interpretation of this data depicts a mechanism where chain scission targets amorphous tie chains between crystalline phases. Targeting the tie-chains lowers the Mn of the polymer without changing the amount of recovered polymer flake. Chain scission of tie-chains and isolating highly crystalline PET lowers the dispersity (Đ) of the polymer chains, as the size of the crystalline lamellae guides the molecular weight of the depolymerized oligomers. When sufficient end groups of PET chains are converted to alcohol groups, the PET flakes break apart into highly crystalline and less disperse polymer. Our results also demonstrate that the oligomeric depolymerization intermediates are readily repolymerized, offering new opportunities to chemically recycle PET more effectively and efficiently, from both an energy and purification standpoint.

Schematic showing the ordering of free HPE polymer in D2O (left), static NOHM-I-HPE in D2O (middle), and NOHM-I-HPE in a negative potential in D2O (right) near a gold electrode.

Tough, semi-crystalline polymers such as poly(ether ether ketone) (PEEK) have recently gained popularity as Material Extrusion (ME) 3D printing feedstocks, but exhibit significant anisotropy when printed using fused filament fabrication (FFF). In this study, we seek to improve interlayer adhesion in PEEK FFF samples by combining the use of bimodal molecular weight polymer blends and post-process thermal annealing. Optimization of the loading of a secondary low molecular weight additive (LMWA) in the blend and identifying effective annealing temperatures leads to increases in the transverse tensile strength of PEEK prints by 250%. We interpret this strength improvement to be a product of tailoring the distribution of polymer crystallinity to induce trans-layer crystallization, which is facilitated by the addition of the LMWA. Thermal and optical analyses of annealed blend samples indicate that crystal structures are homogenously distributed within and between printed layers. The spatial distribution of crystals, and the resulting mechanical properties of the printed samples, are enhanced with incorporation of the LMWA and prescribed post-deposition annealing. The formulation and annealing protocols described herein represent a rational method to control the crystallization in FFF printed samples from crystalline polymers to maximize layer adhesion and improve print isotropy.

Understanding and controlling the fundamental processes governing the coalescence of polymers is vital to enable the design of polymeric materials for improved mechanical performance and quality of manufactured structures, including those fabricated via additive manufacturing techniques. Our group has utilized thermally induced phase separation (TIPS) to produce spherical and size controlled polypropylene (PP) powders from 12,000 (12k), 250,000 (250k), and 340,000 (340k) molecular weight (Mw) PP, including 50-50 wt% blends of 12k/250k,12k/340k, and 250k/340k, and a 33-33-33 wt% blend of 12k/250k/340k to investigate the impact of polymer Mw, and thus zero-shear viscosity, on particle coalescence and its implication in laser powder bed fusion. The particles exhibit similar size distributions with an average particle size, Dx(50), in the range of 58 mu m-86 mu m. The coalescence behavior of the powders, evaluated via hot-stage microscopy, show that adding 12k PP in the blend significantly alters the coalescence dynamics of the 250k and 340k PP, dramatically increasing their coalescence rate. The substantial drop in zero-shear viscosity with addition of 12k PP provides the driving force for the pronounced enhancement in coalescence. Strong agreement between experimental results and the Hopper model of coalescence is observed only if corrected for extensional flow, exemplifying the importance of extensional flow on the coalescence process. The results also indicate that the 12k PP in the blend does not surface segregate in the TIPS process, but is homogeneously distributed in the blend. More broadly, these results provide molecular-level insight into how control of powder molecular weight characteristics and viscosity can offer pathways to optimize the consolidation of particles in manufacturing processes, including laser powder bed fusion.

Recently, nanoparticle organic hybrid materials (NOHMs) have been considered promising electrolytes for energy storage applications due to their unique combination of properties, which include high thermal stability, negligible vapor pressure, and easy synthesis. However, the structural features of NOHMs in electrochemical systems are not well understood. Hence, we investigate the impact of grafting type (ionic vs covalent) on the structure and performance of NOHMs that consist of a silica core and grafted HPE polymer (Jeffamine M2070) in aqueous solution with and without the presence of the supporting electrolyte (0.1 M KHCO3) using small-angle neutron scattering. Careful analyses of the results indicate that even at low grafting density (0.8 chains nm(-2)) and concentration (1-3 wt %), ionic NOHMs solutions contain a free polymer that may interact with the grafted polymer, altering the assembly of NOHMs in solution. Our investigation also elucidates that the covalent NOHM solutions consist of both aggregated and dispersed NOHMs in the solution. Moreover, the addition of the supporting electrolyte affects the assembly and structure of the polymer in the ionic NOHMs solution significantly, whereas only a slight change in the conformation of the grafted polymer is observed for covalent NOHMs. These conformational changes alter the performance of the NOHMs solution, resulting in a dramatic change in viscosity. Careful analysis shows that this significant alteration of solution viscosity in the ionic NOHMs can be traced back to the presence of the free polymer that interacts with the grafted layer and the attenuation of this interaction between the free and grafted polymers with the addition of salt. Thus, these studies elucidate the impact of grafting type on the overall structure, assembly, and performance of functionalized NOHMs in aqueous solution and explicitly correlate the structure and assembly of NOHMs to their transport properties and must be considered when designing functional systems that incorporate NOHMs.

Powder bed fusion (PBF) is a promising technology in polymeric additive manufacturing, whose growth is inhibited by limited material options. In this manuscript, we report the use of thermally induced phase separation (TIPS) to controllably produce polymer powders of polypropylene that are suitable for PBF. Moreover, these studies provide crucial insight into the factors that govern the final size of the produced powder, offering fundamental insight that fosters the rational control of powder fabrication for PBF. More precisely, the impact of polymer concentration, molecular weight, and quench temperature on the size of the powder is demonstrated, where the particle size increases with solution concentration, quench temperature and molecular weight. The molecular weight dependence is consistent with a decrease in polymer solubility with an increase in chain length, while the solution concentration dependence can be explained by the relative fractions of the two phases in the precipitation process of polymer solutions. Careful analysis of the temperature and solution concentration dependence of the powder verifies that droplet coalescence is the governing mechanism in the phase separation‐based particle formation process. Therefore, this fundamental understanding provides pathways to use TIPS to produce powders suitable for PBF from a broad range of polymer solutions.

Poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA) is an organic radical polymer that is a promising active material in organic batteries. The proximity of the radical groups impacts the nature of charge transfer, in which closer packing promotes electron exchange; however, the chain conformation of PTMA is not well understood. Here, the conformation of PTMA in, and its thermodynamic interactions with, battery-relevant solvents is determined using small-angle neutron scattering (SANS). N-methyl-2-pyrrolidone (NMP) and 50:50 (wt %) ethylene carbonate/dimethyl carbonate (EC/DMC) mixtures with PTMA of varying radical content (68 vs 98%) and temperature (25 and 60 degrees C) are examined. Both solvents are theta solvents for PTMA irrespective of radical loading and temperature. PTMA attains an expanded chain conformation in NMP and a more compact polymer chain conformation in EC/DMC. Finally, the electrochemical performance of PTMA films formed from EC/DMC shows improved performance relative to those cast from NMP, which is interpreted to indicate that the compact conformation of PTMA in EC/DMC enables improved inter- and intrachain charge transfer.

It is well-established that micro and nanoplastics (MNPLs) are released from polymers through environmentally triggered bond breaking. However, the mechanism by which this Å-level process leads to nm-m sized fragments is poorly enunciated. Through experimental studies on three distinct chemistries, we demonstrate that only polymers with a semicrystalline morphology produce MNPLs under quiescent conditions. In this morphology, comprised of alternate crystalline and amorphous domains, chain scission occurs faster in amorphous regions. Through theoretical arguments, we show that tie molecules and bridging entanglements (“connectors”), which provide structural integrity to the semicrystalline structure by connecting two adjacent crystals, are preferentially broken. We propose that the cleavage of a threshold amount of connectors (i.e., scission of as little as 1% of chain bonds), leads to the spontaneous release of MNPLs. The resulting fragments comprise highly polydisperse stacks of lamellae, with an individual lamella – several nanometers thick - being the building block. Degradation of the crystals occurs over much longer time scales, explaining the environmental persistence of MNPLs, even under non-quiescent conditions. Since ~70 % of polymers are semicrystalline, engineering connectors may represent an effective strategy to reduce MNPL release rates.

Bisphenol A polycarbonates (PC) are among the important engineering thermoplastics utilized as feedstocks for melt extrusion additive manufacturing, including fused filament fabrication (FFF). However, limited diffusion of polymer chains between adjacent layers and complex thermal histories encountered during the printing process lead to poor interlayer adhesion, residual stress, and voids in the printed parts, which in turn leads to poor mechanical performance and mechanical anisotropy. To address these issues, our group has modified an FFF printer by integrating an ultraviolet (UV)-LED optical fiber into the printer head. This modification allows for real-time illumination of the printed structure during the deposition process, enabling a thorough investigation into its impact on the FFF process and the properties of the resulting printed parts. Examination of the mechanical behavior and fracture surfaces of the printed parts shows that PC printed with UV light attains higher toughness in both the transverse and longitudinal directions as well as decreased void space compared to PC printed without UV light. Careful analysis of the molecular weight characteristics of the printed parts shows that PC printed with UV light has a broader molecular weight distribution with an extended lower molecular weight tail compared to PC parts printed without UV light. This indicates that the polymer chain scission upon UV light exposure leads to the formation of shorter polymer chains and broader range of chain sizes, which in turn increases in the toughness of the UV-light-printed PC. These observations are interpreted to indicate that the change in molecular weight distribution upon UV illumination fosters improved interfilamentous diffusion, consequently lowering the interlayer voids and thus enhancing the mechanical performance. These findings therefore provide foundational insights into how UV light can be used to tune the molecular weight distribution of the polymer and thus impact the FFF process, offering a distinctive and straightforward strategy to tune the properties of parts created by extrusion additive manufacturing of a range of thermoplastics.

Microemulsions (MEs) have many industrial applications, where recent developments have shown that MEs can be utilized for electrochemical applications, including potentially in redox flow batteries. However, understanding the structure and dynamics of these systems, including at a surface, is needed to direct and rationally control their electrochemical behavior. While bulk solution measurements have provided insight into their structure, their assembly at an interface also impacts the electron (to the electrode) and ion (across the surfactant) charge transfer processes in the system. To address this shortcoming, neutron reflectivity experiments and molecular simulations have been completed that document the near surface structure of a series of deuterated water (D2O)/polysorbate-20/toluene MEs on hydrophilic and amphiphilic surfaces. These results show that the microemulsions form complex layered structures near a hard electrode surface, where most layers are not purely one component. Decreasing the D2O concentration in the ME increases the number of and purity of the layers established on the solid surface. These lamellar-type layers transition from the surface to the bulk microemulsion as a series of mixed layers (i.e., containing oil, water, and surfactant) that are consistent with perforated lamellae. Additionally, these mixed lamellae appear to become more perforated with oil and water pathways on an amphiphilic surface. The purity and thickness of these layers will influence the accessibility of an electrode by redox active species, as well as ion transport required to satisfy the electroneutrality condition. This figure depicts the neutron reflectivity experiment and resultant scattering length density profiles, revealing alternating oil- and water-rich layers that vary with surface hydrophilicity. Simulations confirm perforated lamellae in these layers.