Denis Bouyer

Dynamic Interactive Membranes with Pressure‐Driven Tunable Porosity and Self‐Healing Ability

When pressure is applied to dynamic interactive membranes consisting of micelles composed of a triblock copolymer, their morphologies can be fine-tuned. Membranes with a range of porosities are accessible which can regulate and thereby control filtration performance and also display effective autonomous healing.

Removal of nickel ions from aqueous solution by low energy-consuming sorption process involving thermosensitive copolymers with phosphonic acid groups

In order to remove metal ions from wastewaters, thermosensitive copolymers bearing sorption properties toward metal cations were prepared by free radical copolymerization between the N-n-propylacrylamide (NnPAAm) and the (dimethoxyphosphoryl)methyl 2-methylacrylate (MAPC1), followed by a hydrolysis of the phosphonated esters into phosphonic diacid groups ((h)MAPC1). The thermosensitivity and the sorption abilities of the resulting poly(NnPAAm-stat-(h)MAPC1) copolymers were studied. Lower Critical Solution Temperatures (LCST) of these copolymers ranged from 22 °C to 26 °C, depending on the molar ratio of phosphonated monomers and were lower than those obtained with usual poly(N-isopropylacrylamide)-based polymers. The influence of both the temperature and the pH on the sorption properties of the copolymers was evaluated for Ni(2+) cations. The most interesting results were obtained for temperatures around the LCST, i.e. when the proximity of the complexing groups favored the sorption of metallic cations. Concerning the pH effect, the maximum sorption capacity was obtained at pH 7, i.e. in the absence of competition between the sorption of H(+) and Ni(2+) ions on the phosphonic acid groups. The influence of the molar ratio of metal ions and phosphonate moieties was also studied and different sorption mechanisms were proposed.

Synthesis by RAFT of innovative well-defined (co)polymers from a novel phosphorus-based acrylamide monomer

The present contribution reports on the synthesis and controlled polymerization of a novel acrylamide monomer containing phosphonated moieties, namely diethyl-2-(acrylamido)ethylphosphonate. This monomer appears to be of great interest due to the phosphonated moieties, which can lead to a wide range of applications, associated with the chemical stability of the acrylamide compared to more common (meth)acrylate monomers. Reversible Addition–Fragmentation Transfer (RAFT) polymerization of this monomer was investigated using two different trithiocarbonate chain transfer agents, and it allowed the synthesis of poly(diethyl-2-(acrylamido)ethylphosphonate) with controlled molecular weight and low dispersity. Additionally, a diblock copolymer was successfully prepared by a similar RAFT procedure using thermosensitive poly(N-n-propylacrylamide) as a macro-chain transfer agent. A combination of both stimuli-responsive and phosphonated ester or phosphonic diacid (after hydrolysis) containing blocks appears valuable for drug delivery or water treatment, for instance.

A Review on Polymeric Membranes and Hydrogels Prepared by Vapor-Induced Phase Separation Process

In 1918, Zsigmondy and Bachmann presented a new method to induce phase separation of a homogeneous polymeric solution from a vapor phase. The so-called vapor-induced phase separation (VIPS) was born. In a century, the body of knowledge on polymer membranes and hydrogels prepared by VIPS has grown importantly, which suggests the need for a critical review. Slowness of mass transfers involved in VIPS, attributed to the resistance at the gaseous phase/liquid phase interface, permits reaching better control of polymer membrane formation than with the popular wet-immersion process. As a result, a broad variety of morphologies can be obtained and well controlled. The control of testing conditions and formulation parameters also permits tuning and tailoring morphologies, which arises in various membranes properties, and led scientists to investigate the possibility of forecasting mass transfers in VIPS. Therefore, at the end of the twentieth century, first models were developed to describe this process, and validated by comparing simulated data to experimental results. Afterwards, studies demonstrated the possibility of predicting membrane morphologies from the knowledge of operating conditions. This article aims at reviewing the work done so far reporting this process to prepare polymer membranes and hydrogels. The experimental set-ups will be introduced as well as the different polymer/solvent/nonsolvent and polymer/additive(s)/solvent/nonsolvent systems used and the morphologies obtained. The effect of testing conditions and formulation parameters on the structure of the matrices will be subsequently discussed. Close attention will be given to the fundamental theory of VIPS before moving onto the potential applications of such polymer matrices.

Removal of metal ions from aqueous effluents involving new thermosensitive polymeric sorbent.

In this work, new thermosensitive copolymers bearing phosphonated groups were synthesized and used to remove metal pollution. Sorption properties are brought by hydrolyzed (dimethoxyphosphoryl)methyl 2-methylacrylate (hMAPC1) monomer. N-n-propylacrylamide (NnPAAm) led to the thermoresponsive properties of the copolymers. Low lower critical solution temperature (LCST) values were observed, ranging between 20 and 25 °C depending on the molar ratio of each monomer in the copolymer. Sorption properties of these copolymers towards nickel ions were evaluated for increasing temperatures (10-40 °C), Ni ion concentrations of 20 mg L(-1) and pH values between 3 and 7. Best results were observed for temperatures just lower than the LCST (20 °C), when the copolymer was fully soluble in water solution. For temperature higher than the LCST, phosphonic diacid groups accessibility was considerably reduced by the precipitation of the thermosensitive part of the copolymer leading to lower sorption properties. In these conditions, the highest Ni removal by the copolymer was observed for pH = 7, when there was almost no competition between the sorption of H(+) and Ni(2+) ions on the phosphonic acid groups. These optimal conditions enabled removal of about 70% of the nickel in the synthetic effluent.

Sorption properties of a new thermosensitive copolymeric sorbent bearing phosphonic acid moieties in multi-component solution of cationic species

In this paper, original thermosensitive copolymers bearing phosphonic acid groups, namely the poly(N-n-propylacrylamide-stat-2-(methacryloyloxy)methylphosphonic acid) (P(NnPAAm-stat-hMAPC1)) were synthesized, and their sorption properties for three divalent cations (Ni(2+), Ca(2+), Cd(2+)) and one trivalent cation (Al(3+)) have been investigated. The sorption experiments were performed with increasing relative amount of cationic pollution compared to the amount of sorption sites (C(n+)/P ratio) in mono and multi-component solutions to investigate the sorption mechanisms. C(n+)/P proved to strongly affect the sorption capacity and high capacities were obtained for all cations at highest C(n+)/P ratios, reaching one mole of C(sorbed)(n+) per phosphonated moiety. For divalent cations, sorption mechanisms were likely to be described by electrostatic interactions only, whereas for aluminum trivalent cation the sorption not only resulted from electrostatic interactions but also from the formation of coordination binding. The selectivity of the phosphonic acid moieties for aluminum cations was demonstrated, highlighting the interest of P(NnPAAm-stat-(h)MAPC1) for their use for the treatment of metallic pollution from wastewater.

Experimental and Numerical Study on the Drying Process of Natural Rubber Latex Films

The formation of dry films from natural rubber latex was studied through the drying kinetics and compared with film preparations from two synthetic lattices. The experimental results clearly showed that all films displayed very similar behavior, although their chemical composition and particle size distribution were completely different. During the whole process, the evaporation flux was shown to be directly related to the remaining water volume fraction within the film and the reduction in the film transfer area. A numerical model was developed to describe the film formation process and the simulated results were in good agreement with the experimental results.

Self-assembly of PS-PNaSS-PS triblock copolymers from solution to the solid state

Block copolymer assemblies are fascinating objects that have been studied for years. In this work, the PS-PNaSS-PS ABA triblock copolymer was synthesized by RAFT polymerization and self-assembled in a selective medium (THF/water). Various morphologies of aggregates were identified (spheres, cylinders, and vesicles) but we focused on large compound vesicles which gave birth to porous materials after solvent evaporation. The change in solvent composition upon drying was modeled and correlated to the change in morphology observed using microscopy techniques such as AFM, TEM and cryo-TEM. The large compound vesicles were found to partially fuse to form a bulk material before the vesicular compartments were opened to yield pores of about 30 nm.

The first report on phosphonate-based homopolymers combining both chelating and thermosensitive properties of gadolinium: synthesis and evaluation

An original phosphonate-based acrylamide was first prepared in four steps including the incorporation of a valuable carbamoylmethylphosphonate moiety. This monomer was then polymerized, thus leading to poly(diethyl-6-(acrylamido)hexylcarbamoylmethylphosphonate) (P(CPAAm6C)), combining both thermosensitivity and chelating properties. The influence of different parameters (polymer concentration, salt, and acidity) on the P(CPAAm6C) cloud point was determined, mainly considering the salting-out and salting-in effect related to the Hofmeister series. Finally, it was proved that thermosensitive P(CPAAm6C) was efficient for the complexation of gadolinium below and above the cloud point. The latter logically depended on the Gd sorption. To our knowledge, the P(CPAAm6C) polymer represents the only example reported in the literature where only one monomeric unit can allow, on the one hand, the complexation of rare earth elements, in particular gadolinium, and, on the other hand, thermo-responsive properties. The poly(diethyl-6-(acrylamido)hexylcarbamoylmethylphosphonate) polymers open the way to new materials that could be used for the treatment of rare earth elements containing effluents, allowing their recovery while possibly recycling the homopolymer.

How to easily adapt cloud points of statistical thermosensitive polyacrylamide-based copolymers knowing reactivity ratios

The present contribution deals with the ease of controlling the thermosensitivity of statistical copolymers prepared by free radical polymerization playing on the reactivity ratios of both monomers used for the synthesis. The copolymers were prepared using N-n-propylacrylamide (NnPAAm) monomer to achieve the thermoresponsive properties. The second monomer was either (dimethoxyphosphoryl)methyl 2-methylacrylate (MAPC1) or diethyl 2-(acrylamido)ethylphosphonate (DAAmEP) in order to incorporate phosphonic acid moieties after hydrolysis. The architecture of these original statistical copolymers was determined by measuring the reactivity ratios of both (NnPAAm/MAPC1) and (NnPAAm/DAAmEP) monomer couples. By varying the chemical nature of the phosphonated-based monomer (methacrylate or acrylamide), it was possible to get different reactivity ratios, and as a consequence to significantly affect the thermosensitive behavior of the statistical copolymers for a constant proportion of phosphonic acid groups. Additionally, all copolymers showed similar sorption rates toward nickel cations (Ni2+).