The controlled supramolecular assembly of poly(amic acid) ammonium salt (PAAS), a water-soluble polyimide precursor, with branched polyethyleneimine (PEI) is reported. By systematically varying the PAAS:PEI mass ratio, stable non-stoichiometric polyelectrolyte complex (PEC) nanoparticles are obtained, whose size, surface charge, and internal architecture are governed by the polymer in excess. Dynamic Light Scattering (DLS) reveals a non-linear evolution of hydrodynamic diameter, highlighting a pronounced chain compaction occurring in PEI-rich regimes. Transmission Electron Microscopy (TEM) provided morphological evidence of a core-shell organization governed by the polyelectrolyte in excess. Beyond colloidal characterization, these PEC nanoparticle dispersions can be readily cast into homogeneous films. Subsequent thermal treatment showed that complexation does not prevent imidization, supporting this approach as an aqueous route toward nanostructured polyimide-based films.

Polyimide (PI) membranes are attractive for demanding separation processes, but their fabrication typically relies on dipolar aprotic solvents that conflict with current environmental and safety targets. Here, we show that a commercial poly (amic acid) can be converted into a water-soluble poly (amic acid) salt (PAAS) and processed entirely from aqueous media to yield highly porous asymmetric PI membranes. The membranes are formed from a water-based PAAS casting solution through salt-conditioned, temperature-triggered phase separation, followed by glycerol-assisted thermal imidization that preserves the asymmetric macrovoid structure. The resulting PI films combine a thin dense skin with a highly porous sublayer of high overall porosity, delivering high purewater permeance while maintaining a tensile strength close to 50 MPa with excellent thermal stability characteristic of aromatic PI. Liquid-liquid displacement porometry and SEM confirm a well-developed, interconnected pore network that underpins the permeation performance, while filtration tests demonstrate stable water fluxes under elevated transmembrane pressures over multiple cycles. This work establishes an aqueous, PAAS-based route as a viable and scalable strategy for producing high-flux PI ultrafiltration (UF) supports. A comparative life cycle assessment further demonstrates that replacing NMP with water in the membrane formation step significantly reduces the environmental impacts and overall environmental cost, contributing to more sustainable polymeric separation materials.

This work provides a complete methodology to measure the storage modulus of vat 3D-printed polymers via Dynamic Mechanical Analysis (DMA) which could enable real intercomparison of printing materials mechanical performance. We propose an 8-step methodology that includes the determination of the linear viscoelastic region (LVER) and the glass transition temperature (Tα), as well as a stress relief annealing post-treatment that is proven to significantly reduce the dispersion of 3D-printed samples. The methodology applied to various 3D-printed resin samples, achieving repeatability and reproducibility values comparable to those of a reference molded PMMA.

The filtration membranes are often elaborated through a phase separation process where a polymer rich phase and a polymer poor phase spontaneously form through spinodal decomposition. One process that is still not well understood from a theoretical point of view is the non-solvent induced phase separation, where a thermodynamically stable film of a polymer mixture is put in contact with a bad solvent of the polymer. The invasion of the film by this non-solvent drives the film out of stability and leads to spinodal decomposition. During this phase separation, polymer poor and polymer rich regions form. In this article, we present a numerical study of the effect of kinetic coefficients, namely, the relative mobilities of polymer and solvent/non-solvent, on the observed patterns. Using 2D numerical simulations of the ternary Cahn-Hilliard model, we show that, for a given thermodynamic landscape, this parameter has dramatic effects: depending on its value, phase separation may or may not occur. We also show that it can affect the nature of the resulting pattern. In addition to analyzing 3D simulations, we characterize the final pattern using a quantitative indicator of connectivity and show that, for a wide range of initial compositions of the film, the final pattern is bicontinuous. Finally, we also quantify the transport properties of both polymer rich and polymer poor domains.

The majority of polymer membranes are fabricated through phase separation (PS) processes within polymer/solvent systems. Thermodynamic demixing results in the formation of two distinct phases: a rich polymer phase, which solidifies to form the final membrane structure, and a lean polymer phase, which generates the pores following solvent extraction. A critical challenge in this process is the precise control of the morphogenesis mechanisms, which significantly impact the final membrane architecture and, consequently, its functional properties, including permeability and selectivity. The kinetics of phase separation firstly depends on the region in the phase diagram. In the metastable region, the phase separation is governed by nucleation and growth mechanism. In the instable region (spinodal region), the dynamics of phase separation is spontaneous and is driven by spinodal decomposition. In this case, the Cahn-Hilliard equation is used to describe the phase separation dynamics. This equation describes the relaxation dynamics of order parameters driven by the local minimization of the Ginzburg-Landau free energy functional[1]. However, for other mechanisms, such as nucleation and growth, alternative theoretical descriptions may be required. In this study, we conducted simulations of phase separation in both Temperature Induced Phase Separation (TIPS) binary (polymer/solvent) and Non-solvent Induced Phase Separation (NIPS) in ternary (polymer/solvent/non-solvent) systems using 2D and 3D models. The thermodynamic potential was characterized by the Flory-Huggins-De Gennes theory [2]. By systematically varying the initial concentrations and the depth of thermal quenching in the polymer solution, we analyzed the influence of these factors on the phase separation dynamics. The simulation results were further examined using Fourier transform analysis to extract quantitative data on the growth laws governing the formation of microstructures. This work elucidates the impact of processing conditions and operational parameters on the morphology of polymer membranes, as well as on the kinetics of phase separation, providing insights that are crucial for optimizing membrane design and performance.

This research presents an experimental analysis of thermally induced phase separation (TIPS) dynamics in a polymer aqueous solution with very different viscosities (a factor of about a thousand) between separated phases but with no elastic character. The study encompasses the determination of the phase diagram for the polymer‐water system, and the exploration of phase separation (PS) dynamics in critical and off‐critical systems using laser scanning confocal microscopy (LSCM). Thus, domain growth is analyzed through a fast Fourier transform (FFT) from the confocal images, providing insights into the characteristic size and the structure factor scaling. The study focuses on 10 and 12 wt. % polyvinyl alcohol (PVA) solutions, revealing distinct morphologies and growth mechanisms. Despite the huge difference in viscosities between separated phases, PVA 10 exhibits characteristics of spinodal decomposition with interconnected structures and linear growth (L m (t) ∼ t 1 ), indicative of hydrodynamic coarsening. Conversely, PVA 12 shows a trend toward discontinuous structures with growth following L m (t) ∼ t 1/3 , suggesting a diffusion‐driven coalescence mechanism. Notably, both systems demonstrate self‐similar growth patterns despite the significant viscosity contrast, as confirmed by scaled structure factor analysis.

This study investigates the necessity of particle asymmetry for self-propulsion in nanomotors. While conventional wisdom posits that asymmetric designs are crucial for generating phoretic forces or localized bubble propulsion, recent research suggests that symmetrical particles may also exhibit motility. To address this debate, we developed a robust workflow for synthesizing gold grafted silica nanoparticles with precise control over size and shape, enabling the direct comparison of their motile behavior by dynamic light scattering and particle tracking velocimetry. Our results indicate that the inherent asymmetry generated during isotropic gold nanoparticle deposition onto silica surfaces may enable particle motility.

This study compares the mobility behaviour, in a H2O2 environment, of three different geometries of hybrid particle made of silica core functionalized by gold (nanoparticles or layer). It is known that the decomposition of H2O2 on gold surfaces drives mobility; however, the link between mobility orientation and the organization of gold on silica surfaces is still questionable. While conventional wisdom posits that asymmetric designs are crucial for generating phoretic forces or localized bubble propulsion, recent research suggests that symmetrical particles may also exhibit motility. To address this debate, we developed a robust workflow for synthesizing gold grafted silica nanoparticles with precise control over size and shape, enabling the direct comparison of their motile behaviour by dynamic light scattering and particle tracking velocimetry. Our results indicate, first, that a combination of techniques is necessary to overcome their intrinsic limitation and, second, that the inherent asymmetry generated by isotropic gold nanoparticle deposition onto silica surfaces may enable particle motility.

Photopolymerizable resins are increasingly used to generate complex 3D printed parts through stereo lithography, digital light processing (DLP) and liquid crystal display (LCD) 3D printing. Many challenges relating to the resin chemistry and printing parameters still exist and must be addressed in order to entirely control the properties of parts after printing. This work reviews the current knowledge and describes the potential of DLP/LCD methods for printed acrylate resins, as well as the steps necessary to achieve a better control over the mechanical properties of printed materials. Graphical abstract

The design of biocompatible multiple emulsions is an important challenge in the field of controlled delivery systems for protecting and delivering compounds encapsulated and protected in the innermost phase. In this paper, we use biocompatible water – Miglyol®812 water-in-oil-in-water (W/O/W) emulsions stabilized by a stimuli-responsive diblock copolymer consisting of poly(dimethylsiloxane) (PDMS) and poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) to design an easy-to-process new delivery W/O/W system. Such emulsions are formed in a single emulsification step. They present a high encapsulation yield and are shown to be stable over months. As such, the encapsulation of a hydrophilic dye (Alexa fluor) in the innermost water phase is successfully demonstrated over months. These emulsions are stimulable either by a shift in pH level or in ionic strength. The former destabilizes the multiple emulsion and leads to a simple one while the latter partly maintains the multiple character. Eventually both stimulations are effective in the dye release and molecular mechanisms are proposed for explaining the observed two-stage kinetics of release.

We examine how disordering joint position influences the linear elastic behavior of lattice materials via numerical simulations in two-dimensional beam networks. Three distinct initial crystalline geometries are selected as representative of mechanically isotropic materials with low connectivity, mechanically isotropic materials with high connectivity, and mechanically anisotropic materials with intermediate connectivity. Introducing disorder generates spatial fluctuations in the elasticity tensor at the local (joint) scale. Proper coarse-graining reveals a well-defined continuum-level scale elasticity tensor. Increasing disorder aids in making initially anisotropic materials more isotropic. The disorder impact on the material stiffness depends on the lattice connectivity: Increasing the disorder softens lattices with high connectivity and stiffens those with low connectivity, without modifying the scaling between elastic modulus and density (linear scaling for high connectivity and cubic scaling for low connectivity). Introducing disorder in lattices with intermediate fixed connectivity reveals both scaling: the linear scaling occurs for low density, the cubic one at high density, and the crossover density increases with disorder. Contrary to classical formulations, this work demonstrates that connectivity is not the sole parameter governing elastic modulus scaling. It offers a promising route to access novel mechanical properties in lattice materials via disordering the architectures.

Multiple w/o/w emulsions (MEs) are promising systems for protecting fragile hydrophilic drugs and controlling their release. We explore the capacity of a single pH-sensitive copolymer, PDMS60-b-PDMAEMA(50), and salts, to form and stabilize MEs loaded with sucrose or catechin by a one-step mechanical process or a microfluidic method. ME cytotoxicity was evaluated in various conditions of pH. Using the mechanical process, the most stable emulsions were obtained with Miglyol (R) 812 N and isopropyl myristate in a final pH range of 8-12 and [0.3 M-1 M] NaCl concentrations. Conversely, with the microfluidic method, isopropyl myristate at pH 3 without salt was more efficient. Catechin strongly affected the formation of droplets by the mechanical process but did not modify the conditions of stability of MEs obtained by the microfluidic method. The antioxidant power of catechin was preserved in the inner droplets, even in emulsions prepared by the mechanical method at pH 8. An incomplete release of sucrose and catechin from the emulsions was observed and attributed to the interaction of molecules with the copolymer through hydrogen bonding. This study highlights some of the barriers to break to formulate multiple emulsions stabilized by a PDMS-b-PDMAEMA copolymer or other polymers which can form hydrogen bonds interaction with encapsulated drugs.

Amphiphilic peptides that induce catalysis are interesting alternatives to natural enzymes thanks to robustness of their synthesis and the ability to induce certain types of conformations by specific motifs of amino acid sequences. Various studies aimed at mimicking the activity of serine proteases by designed peptides. Here we demonstrate that the order by which the catalytic triad residues are positioned along amphiphilic β-strands influences both assembly structures and catalytic activity. A set of three β-sheet amphiphilic peptides, decorated with different orders of the catalytic triad amino acids, Glu, His and Ser along the strands were evaluated for their catalytic hydrolysis efficiency of p-nitrophenyl acetate (pNPA) substrate. Among the three peptides, Ac-Cys-Phe-Glu-Phe-Ser-Phe-His-Phe-Pro-NH2 (ESH) achieved the greatest catalytic efficiency with a value of 0.19 M−1 s−1, at peptide concentration of 250 μM. This study sheds light on an overlooked factor in designing catalytic amphiphilic assemblies whereby charged residues that make up the active sites, are in fact engaged in intermolecular stabilizing interactions that in turn may hamper their catalytic action.

Small interfering RNAs (siRNA) are attractive and powerful tools to inhibit the expression of a targeted gene. However, their extreme hydrophilicities combined with a negative charge and short plasma half-life counteract their use as therapeutics. Previously, we chemically linked siRNA to squalene (SQ) which self-assembled as nanoparticles (NPs) with pharmacological efficiency in cancers and recently in a hereditary neuropathy. In order to understand the siRNA-SQ NP assembly and fate once intravenously injected, the present study detailed characterization of siRNA-SQ NP structure and its interaction with serum components. From SAXS and SANS analysis, we propose that the siRNA-SQ bioconjugate self-assembled as 11-nm diameter supramolecular assemblies, which are connected one to another to form spherical nanoparticles of around 130-nm diameter. The siRNA-SQ NPs were stable in biological media and interacted with serum components, notably with albumin and LDL. The high specificity of siRNA to decrease or normalize gene expression and the high colloidal stability when encapsulated into squalene nanoparticles offer promising targeted therapy with wide applications for pathologies with gene expression dysregulation.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Self-rolled polymer film: a promising route to microfluidic devices Rémy Brossard, Baptiste Sarrazin, Patrick Guenoun, Florent Malloggi

We present and fully characterize a flow cell dedicated to imaging in liquid at the nanoscale. Its use as a routine sample environment for soft X-ray spectromicroscopy is demonstrated, in particular through the spectral analysis of inorganic particles in water. The care taken in delineating the fluidic pathways and the precision associated with pressure actuation ensure the efficiency of fluid renewal under the beam, which in turn guarantees a successful utilization of this microfluidic tool for in situ kinetic studies. The assembly of the described flow cell necessitates no sophisticated microfabrication and can be easily implemented in any laboratory. Furthermore, the design principles we relied on are transposable to all microscopies involving strongly absorbed radiation (e.g. X-ray, electron), as well as to all kinds of X-ray diffraction/scattering techniques.

In the field of nanomedicine, nanostructured nanoparticles (NPs) made of self-assembling prodrugs emerged in the recent years with promising properties. In particular, squalene-based drug nanoparticles have already shown their efficiency through in vivo experiments. However, a complete pattern of their stability and interactions in the blood stream is still lacking. In this work we assess the behavior of squalene-adenosine (SQAd) nanoparticles - whose neuroprotective effect has already been demonstrated in murine models - in the presence of fetal bovine serum (FBS) and of bovine serum albumin (BSA), the main protein of blood plasma. Extensive physicochemical characterizations were performed using Small Angle Neutron Scattering (SANS), cryogenic transmission electron microscopy (Cryo-TEM), circular dichroism (CD), steady-state fluorescence spectroscopy (SSFS) and isothermal titration calorimetry (ITC) as well as in silico by means of ensemble docking simulations with human serum albumin (HSA). Significant changes in the colloidal stability of the nanoparticles in the presence of serum albumin were observed. SANS, CD and SSFS analyses demonstrated an interaction between SQAd and BSA, with a partial disassembly of the nanoparticles in the presence of BSA and the formation of a complex between SQAd and BSA. The interaction free energy of SQAd nanoparticles with BSA derived from ITC experiments, is about -8 kcal mol-1 which is further supported in silico by ensemble docking simulations. Overall, our results show that serum albumin partially disassembles SQAd nanoparticles by extracting individual SQAd monomers from them. As a consequence, the SQAd nanoparticles would act as a circulating reservoir in the blood stream. The approach developed in this study could be extended to other soft organic nanoparticles.

Building 3D ordered nanostructures by copolymer deposition on a substrate implies a full control beyond the thin film regime. We have used here block copolymers (BCPs) forming bulk lamellar phases to form thick, i.e. much thicker than the lamellar period, structured films on a substrate. Films are formed by a simple method of multiple successive coatings. The film structure is controlled using the combined action of surface templating and annealing time. Sections of the thick layers were characterized by scanning electron microscopy (SEM) after etching of one of the BCP moieties. We show that perfect hexagonally perforated films (HPL) with lamellae parallel to the substrate are formed for a wide thickness range up to 300 nm. Grazing incidence small angle X-ray scattering (GISAXS) confirms such an organization by revealing that perforations sit on a hexagonal lattice. A lamellar organization perpendicular to the substrate is shown to take over for thicker films. A scenario consistent with our observations is proposed, where the sequence of phases results from the balance between surface and stretching energy effects.

Sonochemically produced gold nanoparticles are organized into oriented block copolymer cylinders to obtain anisotropic plasmonic nanocomposite films.