Aug 2026· ACS Macro Letters· 0 citations· 126 references
TL;DR
This perspective establishes NP–dynamic polymer interfaces as a programmable kinetic design parameter for controlling bond-exchange reactions in dynamic polymer networks, opening a pathway toward spatially defined covalent adaptable materials with application-specific and programmable dynamic behavior.
Abstract
Poly(ε-caprolactone) (PCL)-based dynamic polymers are promising adaptive biomaterials due to their biocompatibility, biodegradability, and high chain mobility; however, the onset temperature for bond-exchange reactions, often referred to as topology-freezing temperature, Tv, remains difficult to control and is typically treated as a bulk property governed by catalyst selection and network structure. Consequently, many reported dynamic polymers operate at temperatures well above the biomedical operating window, limiting their biomedical applicability. Here, we propose an interfacial kinetic engineering strategy in which nanoparticle–polymer interfaces act as localized kinetic regulators of dynamic covalent bond exchange. By tailoring nanoparticle (NP) surface chemistry, including functional group density, polarity, and catalytic activity, the activation energy (Ea) can be modulated at the nanoscale, enabling programmable control of Tv. Exchange kinetics in PCL-based dynamic polymers are expected to be highly sensitive to the local chemical environment, indicating that interfacial effects can decouple dynamic behavior from bulk composition. This perspective establishes NP–dynamic polymer interfaces as a programmable kinetic design parameter for controlling bond-exchange reactions in dynamic polymer networks, opening a pathway toward spatially defined covalent adaptable materials with application-specific and programmable dynamic behavior.
The fabrication of biohydrogel coatings faces a trilemma in balancing gelation speed, functional fidelity, and scalability. Rapid reactions often lead to heterogeneous networks due to kinetic trapping, whereas precise methods tend to be slow and difficult to scale. To address this challenge, we propose an Interfacial confined Mutual Catalysis (ICMC) strategy. This approach constructs a cyclic catalytic cascade in which the MXene surface catalyzes monomer polymerization, while the sulfonate groups on the monomer reciprocally enhance the catalytic activity of MXene, resulting in a self‐accelerating polymerization process. This method enables sub‐minute gelation at low temperatures, yielding self‐growing hydrogel coatings with tunable thickness (20–430 µm) and intrinsic multi‐functionalities, including ultra‐low friction (µ < 0.03), strong antibacterial activity (>99.2%), photothermal effect, and excellent biocompatibility. As a proof of concept, MXene‐hydrogel coated surgical sutures reduce surface friction by 83% relative to commercial sutures and significantly mitigate inflammation and epithelial hyperplasia in a rat wound model. Notably, the ICMC approach is compatible with roll‐to‐roll (R2R) processing, enabling continuous and programmable fabrication of multifunctional hydrogel coatings. This work opens a door for easy and scalable manufacture of hydrogels‐based functional biomaterials and medical devices.
Poly(3,4‐ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) hydrogels have emerged as a versatile class of mixed ionic‐electronic conductors for next‐generation bioelectronic interfaces, owing to their unique combination of high conductivity, mechanical compliance, and aqueous processability. This review systematically examines the chemistry‐driven design principles governing PEDOT:PSS hydrogel systems, with particular emphasis on how polymerization strategies, structural organization, and secondary doping regulate their electrical, mechanical, and interfacial properties. Key synthesis approaches, including in situ, oxidative, electrochemical, and solution polymerization, as well as physical fabrication methods such as freeze–thaw processing, ionic liquid gelation, electrospinning, and additive manufacturing, are critically analyzed in the context of network formation and charge transport pathways. The resulting hydrogels exhibit tunable modulus, enhanced conductivity, and robust adhesion, enabling stable performance under dynamic physiological conditions. Emerging applications in wearable and therapeutic bioelectronics, including electrophysiological signal monitoring, multimodal strain and pressure sensing, soft circuits, and therapeutic systems, are highlighted, demonstrating their ability to bridge the mechanical–electrical mismatch between conventional electronics and biological tissues. Despite significant progress, challenges related to long‐term stability, dehydration‐induced drift, acidity, scalability, and standardization remain. Future directions are outlined, focusing on sustainable chemistries and advanced manufacturing strategies to accelerate clinical translation and large‐scale deployment of PEDOT:PSS‐based bioelectronic systems.
Bangul Khan, Zainab Ali, R. Khalid et al.· Advanced Materials & Technol...· 0 citations
MXenes are a rapidly expanding family of two-dimensional transition-metal carbides, nitrides, and carbonitrides whose physicochemical behavior in aqueous and biological environments is dominated by their surface terminations (e.g., -O, -OH, and -F), rendering them intrinsically active solid-liquid interfaces. These terminations regulate interfacial charge distribution, hydration structure, adsorption equilibria, and colloidal stability, positioning MXenes as dynamic interfacial systems rather than passive nanomaterials. Rational control of surface termination chemistry therefore represents a central strategy for governing MXene interactions with electrolytes, proteins, and biological media. This review provides a comprehensive and critical analysis of recent advances in MXene surface-termination engineering from the perspective of interfacial and colloidal science, with emphasis on etching routes, post-synthetic modification, dimensional tailoring (2D, 3D, and emerging 4D architectures), and characterization approaches relevant to interfacial behavior. We examine how termination chemistry controls key interfacial properties, including zeta potential, dispersion stability in physiological electrolytes, hydration-mediated wetting, and protein corona formation, and how these interfacial factors collectively shape biological responses such as cytotoxicity, inflammatory signaling, antibacterial activity, and reactive oxygen species generation. Particular attention is devoted to termination-driven charge regulation and coordination chemistry at solid-liquid interfaces, which govern adsorption-desorption dynamics, molecular loading, and stimulus-responsive release, as well as the modulation of optical and magnetic responses. By critically comparing reported systems and explicitly addressing unresolved challenges related to termination heterogeneity, interfacial aging, and scalability, this review clarifies structure-interface-function relationships that underpin MXene performance in complex environments. Finally, we identify emerging strategies and open questions for designing surface-terminated MXenes with predictable and controllable interfacial behavior, highlighting their broader relevance as model systems for dynamic solid-liquid interfaces with bio-functional implications.
M. A. Dheyab, Wesam Abdullah, Mutaz Mohammad Alsardi et al.· Advances in Colloid and Inte...· 1 citation
Multilayer hydrogels with spatially controllable mechanical and functional properties are increasingly valuable, yet their utility is often constrained by fabrication challenges such as weak interfacial adhesion as well as reliance on cytotoxic photoinitiators and UV exposure. This study presents a simple, robust, and photoinitiator-free method to engineer multilayer poly(ethylene glycol) (PEG) hydrogels using off-stoichiometry thiol–ene (OSTE) Michael addition chemistry. By deliberately utilizing an alternating thiol-rich and vinyl sulfone-rich PEG formulation, residual functional groups are preserved at the layer interfaces and subsequently form covalent bonds between the adjacent layers, enabling strong interfacial adhesion without UV irradiation, photoinitiators, or adhesives. The resulting hydrogels exhibited rapid and tunable gelation (1–5 min), with mechanical properties spanning ∼0.5–6 kPa through varying polymer concentration (5–10 wt %) and thiol–ene ratio (0.6–1.6). Ellman’s assay confirmed the presence of stoichiometry-dependent unreacted thiol groups, validating the proposed interfacial bonding mechanism. Peel tests revealed strong interfacial adhesion, with failure occurring within the bulk material rather than at the interface. Nanoindentation further revealed spatially defined stiffness profiles across the multilayer construct, confirming precise mechanical compartmentalization. The hydrogels displayed tunable swelling behavior and degradation profiles depending on the formulations. Additionally, all single- and multilayer hydrogels maintained high cytocompatibility (>90% NIH/3T3 mice fibroblast viability) independent of polymer concentration, thiol–ene ratios, or layering. Incorporation of alginate microparticles provided an additional strategy for modulating hydrogel properties, significantly reducing swelling and enhancing stiffness while preserving structural integrity. Overall, the findings established a platform for engineering heterogeneous hydrogel constructs with spatially controlled properties, biofunctionality, and compatibility features that make them relevant for biomedical applications.
Polymer-based coatings often incorporate fillers or inclusions into the polymer matrix to tune application-specific physical and chemical properties. Furthermore, the presence of specific solvents can either promote or impede dispersal of the inclusions and polymer chains. Here, all-atom molecular dynamics (MD) simulations are performed to probe the formation of interfacial regions in metal-organic framework (MOF)-polymer composites by including nanoscale crystallites of UiO-66 in a binder of a polyurethane or polyhydroxyurethane solvated with hexane or hexanol. We study the effect of different surface chemistries on the metal oxide nodes (hydroxyl, formate, or acetate groups), calculating polymer and solvent densities and interaction energies. We report secondary trends in chain adsorption (depletion) near the MOF surface as a function of different surface chemistries, while the polymer-solvent and solvent-solvent interactions appear as the primary factors controlling the interfacial uniformity. The simulations show that chain penetration into the MOF can be either entirely impeded by the choice of the blending solvent or promoted by the particular surface functionalization. Energetic barriers from the MD are directly extracted to quantify chain interpenetration of the MOF and reveal that interpenetration is a stabilizing process during interface formation and strongly dependent upon solvent presence and surface chemistry.
M. A. Browe, Adam R. Hinkle, I. Iordanov et al.· Langmuir· 0 citations
Ultra-small nanoparticles (USNPs), characterized by fast dynamics, ultra-small dimensions and dense surface functionalities, offer an underexplored yet powerful strategy to simultaneously modulate polymer behavior and NP assembly. Herein, we introduce a versatile materials design strategy based on USNP complexation to reprogram polymer chain dynamics and manipulate NP ordering. Using 1 nm metal oxide NP, H3PW12O40 (PTA) complexed with polyvinyl alcohol (PVA), we show that USNPs induce anomalous viscosity reduction via chain collapse, enabling residual-stress-free film fabrication. The size of PTA, significantly smaller than the polymer coil dimensions, combined with strong attractive interactions to PVA chains, induces chain collapse in solution. Their ultrahigh surface area disrupts polymer crystallinity and forms humidity-responsive supramolecular networks, demonstrating a humidity‑assisted proof‑of‑concept route for optical‑film orientation and fixation. Moreover, the energy barrier for USNP dynamics is substantially lower than that of colloidal NPs, allowing stretch-induced orientation under uniaxial extension. In situ x-ray scattering confirms unidirectional PTA orientation upon mechanical stretching, yielding promising birefringence (Δn ≈ 0.018). This work establishes USNP complexation as a versatile strategy to simultaneously reprogram polymer processability and achieve precise NP ordering for functional devices.
Jie Deng, Jiadong Chen, Bin Wang et al.· Angewandte Chemie· 0 citations