arXiv subjects

Sixtine de Chateauneuf-Randon

Publications and source records attributed to Sixtine de Chateauneuf-Randon.

4 recordsLinked to original sources

arXiv2026

Nanostructure of PEGDA-PEG hydrogel membranes and how it controls their permeability

The spacial heterogeneity of hydrogels composed of PEGDA and added polymer chains is expected to play a crucial role on their transport properties which can be exploited in filtration or tissue engineering. However little is known about the arrangement of the polymer chains in the matrix and the length scales of these heterogeneities. Here we combine solid-state NMR and Small Angle Neutron Scattering to unravel the structure and dynamics of PEGDA hydrogels containing added PEG chains of various concentrations. Our results show that the samples present heterogeneities in both the PEGDA and PEG concentrations and suggest that the PEG chains entangle with the PEGDA network. When plotting the sample permeability, K, as a function the specific surface of the PEGDA heterogeneities we obtain a master curve, showing that the heterogeneity of the PEGDA matrix controls the permeability of the sample. Moreover the scaling K ___ V/S suggests a structure composed of facetted PEGDA/PEG heterogeneities separated by a network of aqueous thin and flattened films in which the water can permeate.

cond-mat.soft↗

arXiv2024

Tuning the water intrinsic permeability of PEGDA hydrogel membranes by adding free PEG chains of varying molar masses

We explore the effect of poly (ethylene glycol) (PEG) molar mass on the intrinsic permeability and structural characteristics of poly (ethylene glycol) diacrylate PEGDA/PEG composite hydrogel membranes. We observe that by varying the PEG content and molar mass, we can finely adjust the water intrinsic permeability over several orders of magnitude. Notably, we show the existence of a maximum water intrinsic permeability, already identified in a previous study to be located at the critical overlap concentration C^* of PEG chains, for the highest PEG molar mass studied. Furthermore, we note that the maximum intrinsic permeability follows a non-monotonic evolution with respect to the PEG molar mass and reaches its peak at 35 000 g.mol-1. Besides our results show that a significant fraction of PEG chains is irreversibly trapped within the PEGDA matrix even for the shortest molar masses down to 600 g.mol-1. This observation suggests the possibility of covalent grafting of PEG chains to the PEGDA matrix. CryoSEM and AFM measurements demonstrate the presence of large micron-sized cavities separated by PEGDA-rich walls whose nanometric structure strongly depends on the PEG content. By combining our permeability and structural measurements, we suggest that the PEG chains trapped inside the PEGDA rich walls induce nanoscale defects in the cross linking density, resulting in an increased permeability below C^*. Conversely, above C^*, we speculate that partially-trapped PEG chains may form a brush-like arrangement on the surface of the PEGDA-rich walls, leading to a reduction in permeability. These two opposing effects are anticipated to exhibit molar-mass-dependent trends, contributing to the non-monotonic variation of the maximum intrinsic permeability at C^*. Overall, our results demonstrate the potential to fine-tune the properties of hydrogel membranes, offering new opportunities in separation applications.

cond-mat.soft↗

arXiv2023

Sieving and clogging in PEG-PEGDA hydrogel membranes

Hydrogels are promising systems for separation applications due to their structural characteristics (i.e. hydrophilicity and porosity). In our study, we investigate the permeation of suspensions of rigid latex particles of different sizes through free-standing hydrogel membranes prepared by photopolymerization of a mixture of poly (ethylene glycol) diacrylate (PEGDA) and large poly (ethylene glycol) (PEG) chains of 300 000 g.mol-1 in the presence of a photoinitiator. Atomic force microscopy (AFM) and cryoscanning electron microscopy (cryoSEM) were employed to characterize the structure of the hydrogel membranes. We find that the 20 nm particle permeation depends on both the PEGDA/PEG composition and the pressure applied during filtration. In contrast, we do not measure a significant permeation of the 100 nm and 1 $μ$m particles, despite the presence of large cavities of 1 $μ$m evidenced by cryoSEM images. We suggest that the PEG chains induce local nanoscale defects in the cross-linking of PEGDA-rich walls separating the micron size cavities, that control the permeation of particles and water. Moreover, we discuss the decline of the permeation flux observed in the presence of latex particles, compared to that of pure water. We suggest that a thin layer of particles forms on the surface of the hydrogels.

cond-mat.soft↗

arXiv2022

Large and non-linear permeability amplification with polymeric additives in hydrogel membranes

Hydrogels which are hydrophilic and porous materials have recently emerged as promising systems for filtration applications. In our study, we prepare hydrogel membranes by the photopolymerization of a mixture of poly (ethylene glycol) diacrylate (PEGDA) and large poly(ethylene glycol) (PEG) chains of 300 000 g.mol-1 in the presence of a photoinitiator. We find that this addition of free PEG chains induces a large and non-linear increase of the water permeability. Indeed, by changing the content of PEG chains added, we obtain variations of the hydrogel water permeability over two orders of magnitude. The highest water permeability values are obtained for the membranes when the PEG concentration is equal to its critical overlap concentration C*. Moreover, we find that the flow rate of water through the membranes varies non-linearly with the pressure. We relate this result to the deformability of the membranes as the applied pressure leads to a compression of the pores. This study provides new perspectives for the design of flexible hydrogel membranes with controlled permeability and their application in water treatment and bioseparation.

cond-mat.mtrl-sci↗