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Surface-attached hydrogel films with well-controlled chemistry are a new approach of polymer thin layers and an actual alternative to polymer brushes and layer-by-layer assemblies. The advantage is that the thickness of hydrogel films can widely range from a few nanometers to several micrometers. Hydrogel films can also remarkably respond to stimuli such as temperature: (i) the thickness change is of great amplitude, fourfold and more, which could not be reached with the geometry of polymer brushes or layer-by-layer assemblies, (ii) the time response is very short (less than 1 s), and (iii) the swelling-to-collapse transition is narrow (a small temperature change of a few degrees may be enough). Poly(N-isopropylacrylamide) (PNIPAM) is the most temperature-responsive polymer investigated with a lower critical solution temperature (LCST) of around 32 °C. However, it is relevant to have the available polymers responding to various transition temperatures with the advantage of keeping the same chemistry. Poly[oligo(ethylene glycol) methacrylate] (PEGMA) meets these specifications since its transition temperature can be finely tuned with the number of oligo ethylene glycol units, while it attractively combines biocompatibility with PEG side chains. Here, we report the synthesis and the temperature-responsive properties of poly(PEGMA) hydrogel thin films. We used a simple, versatile, and well-controlled approach through thiol-ene click reaction, the so-called cross-linking and grafting, to synthesize surface-attached poly(PEGMA) hydrogel films with various thickness. We show that the transition temperature of poly(PEGMA) hydrogel films ranges from 15 to 60 °C if the number of PEG units is from 2 to 5. This transition temperature can also be finely adjusted for hydrogel films containing copolymers or mixing homopolymers of PEGMA with a suitable ratio. Moreover, the LCST properties, swelling-to-collapse amplitude and transition temperature, are not sensitive to salt. In particular, there is no effect on the LCST properties of surface-attached poly(PEGMA) hydrogel films in phosphate saline buffer, which is promising for applications in biology such as injectable hydrogels, drug delivery systems, hydrogel-based microfluidic valves, and flow switches for biotechnologies.

International audience; Driven by the growing concern about the release of untreated emerging pollutants and the need for determining small amounts of these pollutants present in the environment, novel biosensors dedicated to molecular recognition are developed. We have designed biosensors using a novel class of grafted polymers, surface-attached hydrogel thin films, on conductive transducers as a biocompatible matrix for biomolecule immobilization. We showed that they can be dedicated to the molecular recognition of diclofenac (DCL). The immobilization of the aptamer onto surface-attached hydrogel thin films by covalent attachment provides a biodegradable shelter, providing the aptamer with excellent environments to preserve its active and functional structure while allowing the detection of DCL. The grafting of the aptamer is obtained using the formation of amide bonds via the activation of carboxylic acid groups of the poly(acrylic acid) hydrogel thin film. For improved sensitivity and higher stability of the sensor, a high density of the immobilized aptamer is enabled. The aptamer-modified electrode was then incubated with DCL solutions at different concentrations. The performances of the aptasensor were investigated by electrochemical impedance spectroscopy. The change in charge-transfer resistance was found to be linear with DCL concentration in the 30 pM to 1 μM range. The detection limit was calculated to be 0.02 nM. The improvement of the limit of detection can be mainly attributed to the three-dimensional environment of the hydrogel matrix which improves the grafting density of the aptamer and the affinity of the aptamer to DCL.

We investigate the adsorption of pH- or temperature-responsive polymer systems by ellipsometry and neutron reflectivity. To this end, temperature-responsive poly (N-isopropylacrylamide) (PNIPAM) brushes and pH-responsive poly (acrylic acid) (PAA) brushes have been prepared using the &ldquo, grafting onto&rdquo, method to investigate the adsorption process of polymers and its reversibility under controlled environment. To that purpose, macromolecular brushes were designed with various chain lengths and a wide range of grafting density. Below the transition temperature (LCST), the characterization of PNIPAM brushes by neutron reflectivity shows that the swelling behavior of brushes is in good agreement with the scaling models before they collapse above the LCST. The reversible adsorption on PNIPAM brushes was carried out with linear copolymers of N-isopropylacrylamide and acrylic acid, P(NIPAM-co-AA). While these copolymers remain fully soluble in water over the whole range of temperature investigated, a quantitative adsorption driven by solvophobic interactions was shown to proceed only above the LCST of the brush and to be totally reversible upon cooling. Similarly, the pH-responsive adsorption driven by electrostatic interactions on PAA brushes was studied with copolymers of NIPAM and N,N-dimethylaminopropylmethacrylamide, P(NIPAM-co-MADAP). In this case, the adsorption of weak polycations was shown to increase with the ionization of the PAA brush with interactions mainly located in the upper part of the brush at pH 7 and more deeply adsorbed within the brush at pH 9.

International audience; A new strategy for the fabrication of micropatterns of surfaceattached hydrogels with well-controlled chemistry is reported. The “grafting onto” approach is preferred to the “grafting from” approach. It consists of cross-linking and grafting preformed and functionalized polymer chains through thiol−ene click chemistry. The advantage is a very good control without adding initiators. A powerful consequence of thiol−ene click reaction by UV irradiation is the facile fabrication of micropatterned hydrogel thin films by photolithography. It is achieved either with photomasks using common UV lamp or without photomasks by direct drawing due to laser technology. Our versatile approach allows the fabrication of various chemical polymer networks on various solid substrates. It is demonstrated here with silicon wafers, glass and gold surfaces as substrates, and two responsive hydrogels, poly(N-isopropylacrylamide) for its responsiveness to temperature and poly(acrylic acid) for its pH-sensitivity. We also demonstrate the fabrication of stable hydrogel multilayers (or stacked layers) in which each elementary layer height can widely range from a few nanometers to several micrometers, providing an additional degree of freedom to the internal architecture of hydrogel patterns. This facile route for the synthesis of micrometer-resolute hydrogel patterns with tailored architecture and multiresponsive properties should have a strong impact

International audience; A facile route for the fabrication of surface-attached hydrogel thin films with well-controlled chemistry and tailored architecture on wide range of thickness from nanometers to micrometers is reported. The synthesis, which consists in cross-linking and grafting the preformed and ene-reactive polymer chains through thiol−ene click chemistry, has the main advantage of being well-controlled without the addition of initiators. As thiol−ene click reaction can be selectively activated by UV-irradiation (in addition to thermal heating), micropatterned hydrogel films are easily synthesized. The versatility of our approach is illustrated by the possibility to fabricate various chemical polymer networks, like stimuli-responsive hydrogels, on various solid substrates, such as silicon wafers, glass, and gold surfaces. Another attractive feature is the development of new complex hydrogel films with targeted architecture. The fabrication of various architectures for polymer films is demonstrated: multilayer hydrogel films in which single-networks are stacked one onto the other, interpenetrating networks films with mixture of two networks in the same layer, and nanocomposite hydrogel films where nanoparticles are stably trapped inside the mesh of the network. Thanks to its simplicity and its versatility this novel approach to surface-attached hydrogel films should have a strong impact in the area of polymer coatings

We study the pH-responsive behavior of random polyampholyte brushes synthesized by surface-initiated Atom Transfer Radical Polymerization. We define the “annealed” polyampholyte as the random copolymer that contains weak acid (methacrylic acid) and weak base (2-(dimethylamino)ethyl methacrylate) units. The “semi-annealed” polyampholyte is defined as the random copolymer that contains the methacrylic acid and a strong base unit (the quaternized amine). The structure of the polyampholyte brushes in aqueous solutions at different pH is determined using neutron reflectivity. The monomer density profile and therefore the brush thickness are obtained. Polymer brushes with various grafting densities are compared. We demonstrate that the structure of the polyampholyte brush depends strongly on the net charge of the chains. With an excess of charge, the brush is as stretched as a polyelectrolyte brush, and the swelling behavior is in good agreement with the scaling laws. At the isoelectric point corresponding to a...

Electrogeneration of reducers at a microelectrode allows us to locally debrominate a surface bound polymerization initiator. Once submitted to atom transfer radical polymerization, patterns of nanometer polymer structures are formed on the surfaces. The surface reduction rate, controlled by the microelectrode scan rate and the reducer strength, affects the dimensions of the patterns. The reducer strength allows to tune the surface density of the initiator layer and then the elongation of the polymer brushes grown in the locally etched regions.

The interfacial thickness and mechanical strength of several model interfaces between immiscible polymer melts were investigated. The interfacial width at equilibrium was determined by neutron reflectivity, and the adhesion energy was determined with an asymmetric probe test method inspired of the tests used for soft adhesives. A very good correlation was found between the adhesion energy and the measured interfacial width in a qualitatively similar way as what was observed for interfaces between glassy polymers. For polymer pairs with χ values ranging from 0.002 to 0.05, the mechanical strength of the interface was controlled by the degree of interpenetration, or in other terms, by the interfacial free energy between the two polymers. For lower values of χ, the interfacial strength was comparable to the fracture strength of the weakest of the two bulk polymers, while for higher values of χ, the thermodynamic work of adhesion and the polymer surface mobility are probably controlling the interfacial strength.

We synthesize polybase brushes and investigate their swelling behavior. Poly(2-(dimethylamino)ethyl methacrylate)) (PDMAEMA) brushes are prepared by the "grafting from" method using surface-initiated Atom Transfer Radical Polymerization to obtain dense brushes with relatively monodisperse chains (PDI = 1.35). In situ quaternization reaction can be performed to obtain poly(2-(trimethylamino)ethyl methacrylate)) (PTMAEMA) brushes. We determine the swollen thickness of the brushes using ellipsometry and neutron reflectivity techniques. Brushes are submitted to different solvent conditions to be investigated as neutral brushes and weak and strong polyelectrolyte brushes. The swelling of the brushes is systematically compared to scaling models. It should be pointed out that the scaling analysis of different types of brushes (neutral polymer and weak and strong polyelectrolyte brushes) is performed with identical samples. The scaling behavior of the PDMAEMA brush in methanol and the PTMAEMA brush in water is in good agreement with the predicted scaling laws for a neutral polymer brush in a good solvent and a polyelectrolyte brush in the osmotic regime. The salt-induced contraction of the quaternized brush is observed for high salt concentration, in agreement with the predicted transition between the regimes of the osmotic brush and the salted brush. From the crossover concentration, we calculate the effective charge ratio of the brush following the Manning counterion condensation. We also use PDMAEMA brushes as pH-responsive polybase brushes. The swelling behavior of the polybase brush is intermediate with respect to the behavior of the neutral polymer brush in a good solvent and the behavior of the quenched polyelectrolyte brush, as expected. The effective charge ratio of the PDMAEMA brush is determined as a function of pH using the scaling law of the polyelectrolyte brush in the osmotic regime.

Temperature-responsive properties of surface-attached poly(N-isopropylacrylamide) (PNIPAM) network films with well-controlled chemistry are investigated. The synthesis consists of cross-linking and grafting preformed ene-reactive polymer chains through thiol--ene click chemistry. The formation of surface-attached and cross-linked polymer films has the advantage of being wellcontrolled without any caution of no-oxygen atmosphere or addition of initiators. PNIPAM hydrogel films with same cross-link density are synthesized on a wide range of thickness, from nanometers to micrometers. The swelling-collapse transition with temperature is studied by using ellipsometry, neutron reflectivity, and atomic force microscopy as complementary surface-probing techniques. Sharp and high amplitude temperature-induced phase transition is observed for all submicrometric PNIPAM hydrogel films. For temperature above LCST, surface-attached PNIPAM hydrogels collapse similarly but without complete expulsion of water. For temperature below LCST, the swelling of PNIPAM hydrogels depends on the film thickness. It is shown that the swelling is strongly affected by the surface attachment for ultrathin films below $\sim$150 nm. For thicker films above 150 nm (to micrometers), surface-attached polymer networks with the same cross-link density swell equally. The density profile of the hydrogel films in the direction normal to the substrate is confronted with in-plane topography of the free surface. It results that the free interface width is much larger than the roughness of the hydrogel film, suggesting pendant chains at the free surface., in Langmuir, American Chemical Society, 2015, LANGMUIR, 31 (42), pp.11516-11524

We discuss the nematic order parameter and the polymer concentration profile for a solid surface carrying grafted chains. Different regimes are found, depending upon the polymer chain length and the grafting density. These ideas are compared with experimental results obtained with polystyrene in the presence of pentylcyanobiphenyl.

International audience; We investigated the effect of specific interactions on the structure of interfaces between a brush and a hydrogel on the polymer chain length scale. We used a model system for which the interactions between the brush and the gel are switchable. We synthesized weak polyelectrolyte brushes of poly(acrylic acid) and hydrogels of polyacrylamide and poly(N,N-dimethylacrylamide) which interact solely when the poly(acrylic acid) is mainly in its acidic form. The monomer density profiles of the poly(acrylic acid) brush immersed in pure deuterium oxide (D2O) or in contact with a D2O-swollen gel were determined by neutron reflectivity. At pH 2 when the brush is in its neutral form, it interacts with the gel by hydrogen bonds while at pH 9 when the brush is a polyelectrolyte it is not interacting with the gel. Our results show that the presence of interactions with the gel at pH 2 increases the swelling ratio of the brush relative to that in pure D2O, meaning that the brushes exhibit conformations which are more extended from the surface than in the absence of interactions.

The complexation and the distribution of various cations, bound to a poly(styrene sulfonate) brush, have been investigated using infra-red spectroscopy and neutron reflectivity. Small counterions (like tetremethylammonium) are distributed throughout the brush in such a way that a local electroneutrality is ensured. They also exchange readily with other bulk small cations. On the other hand, model polycations are irreversibly trapped to the brush despite a relative small number of ionic bonds involved in the complexation. These complexed polycations are localized at the outer border of the brush, forming a macromolecular barrier. However, this spatial segregation does not allow the buildup of polyelectrolyte multilayers. Cationic surfactants are associated stoichiometrically with the brush sulfonates but unlike small counterions, this complexation is “irreversible” and induces a restructuring of the polymer interface.

International audience; The swelling of poly(acrylic acid) brushes in aqueous solutions is studied by neutron reflectivity. The brushes are synthesized on silicon wafers using a grafting onto approach and their stretching is investigated at various pH, grafting densities, and chain lengths. Neutron reflectivity provides the average thickness and, more interestingly, the density profile of the brushes. The profiles obtained experimentally are in good agreement with theory. The swelling ratio of the poly(acrylic acid) brushes is compared with that of other polymer brushes formerly investigated using classic scaling laws. Owing to a new representation with the normalized thickness, it is demonstrated that there is a general behavior for all polymer brushes with a master curve for neutral polymer brushes and for polyelectrolyte brushes.

Following the great success of traditional microfluidic devices across many disciplines, a new class of microfluidic systems emerged in recent years, which features finely tuned, localized surface modifications within the microstructures in order to keep up with the demand for devices of ever increasing complexity (lab on chip, assay on chip, etc.). Graft photopolymerization has become a powerful tool for such localized surface modifications particularly in combination with poly(dimethylsiloxane) (PDMS) devices, as it is compatible with many functional monomers and allows for high spatial resolution. However, application within enclosed PDMS microstructures and in particular well-controlled surface-directed polymerization remains challenging. Detailed understanding of the interaction between photoinitiator, benzophenone (BP), and polymer matrix is needed. We have developed a visualization technique, which allows for observation of reacted BP in situ within the PDMS matrix. We present a detailed study on solvent-driven BP diffusion providing results essential to successful surface treatment. We also identified and investigated photoinitiator inhibition by oxygen and provide appropriate mitigation strategies.

Responsive polymers were prepared by copolymerizing a small amount of ionizable monomers, acrylic acid or N,N-dimethylaminopropylmethacrylamide, with N-isopropylacrylamide (NIPA) and the solubility in aqueous solution of these PNIPA derivatives were quantitatively studied. From differential scanning calorimetry experiments, it was shown that the pH strongly influences the phase separation of these copolymers (temperature and enthalpy), which totally disappears when ionizable groups are fully charged. At pH 7, all PNIPA copolymers remain soluble in water at all temperatures but their mixtures show a phase separation above a critical temperature due to the formation of a reversible inter-polyelectrolyte complex. When the responsive stickers are grafted on a poly(acrylamide) backbone, pH and temperature are still able to drive the association process at a local scale, giving rise to a sol/gel transition of semi-dilute solutions. The structure and the viscoelastic properties of these macromolecular assemblies are investigated by small angle neutron scattering and rheology and their responsivity is discussed as a function of pH and temperature.

We synthesize and investigate the swelling behavior of polyelectrolyte and polyampholyte grafted layers on planar substrates. The polymer brushes are prepared using the "grafting from" method with surface-initiated atom transfer radical polymerization (ATRP), which allows a good control of the chain length and a weak polydispersity of chains. Ellipsometry and neutron reflectivity are used to determine the swollen thickness and the monomer volume fraction profile. The scaling behavior of the neutral polymer brush and the strong polyelectrolyte brush is in good agreement with scaling laws predicted by mean-field theories. The swelling behavior of the pH-responsive polybase brush is between the situation of the neutral polymer brush in good solvent and the quenched polyelectrolyte. Polyampholyte brushes are contracted in the pH range of zero net charge. A barrier zone likely due to the attraction between positively and negatively charged monomer units is observed in the density profile. This barrier could prevent from a collective ionization of the chains and reduce the expected collapse of the brush.

Dense poly(styrene sulfonate sodium salt) brushes were prepared on silicone wafers using a two-step procedure: polystyrene (PS) chains, terminated by a reactive trichlorosilane group, were first covalently grafted, and then the PS brush was converted to a poly(styrene sulfonate) brush by a soft sulfonation reaction. Ellipsometry and infrared spectroscopy in ATR were used to characterize the samples and to optimize the procedure: in particular, the sulfonation was shown to be homogeneous along the chain backbone and the neutralization complete. In some cases, the polymer layer revealed to be quite fragile: the chains were pulled out of the brush. A consolidation treatment which consisted in grafting oligomers inbetween the long PS chains significantly increased the robustness of the layer. This might be relevant for industrial applications.

Temperature-responsive surface-attached hydrogel thin films with various LCST/UCST (Lower/Upper Critical Solution Temperature) were designed for specific applications. The chemical polymer networks covalently attached on plane solid substrates were synthesized by a versatile and straightforward approach using thiol-ene click chemistry. It consists in coating ene-reactive polymers and dithiol crosslinkers on thiol-modified substrates, the thiol-ene click reaction allowing simultaneous cross-linking between chains and grafting on the surface. The CLAG (Cross-Linking And Grafting) strategy provides chemically stable and reproducible hydrogel films with a wide range of thickness and with the desired temperature-responsive properties. Ene-functionalized hydrophilic polymers can be synthesized using free radical copolymerization of the desired monomer with allyl methacrylate in organic solvent or co-solvent with water. Another way is the synthesis in water in two steps: the desired monomer is copolymerized with acrylic acid and then the copolymer is post-modified by amidification. Three polymer families were investigated: poly(PEGMA), poly(acrylamide) derivatives and poly(zwitterions). The transition temperature of the hydrogel films is determined by measuring the thickness in aqueous solutions at different temperatures with ellipsometry. Poly(PEGMA) hydrogel films show LCST properties with the transition temperature increasing with the number of PEG units. The LCST ranges from 15 °C to 60 °C with two to five PEG units in the pendant chains. The LCST can also be adjusted using mixed copolymers hydrogel. Poly(acrylamide) derivatives hydrogel films have both LCST and UCST properties. Poly(sulfobetaine) hydrogel films show very interesting UCST behavior in addition to be anti-fouling, which is very promising for biology applications., Les films minces d'hydrogels thermosensibles à propriétés LCST/UCST (Lower/Upper Critical Solution Temperature) avec des températures de transition variables ont été mis au point pour des applications spécifiques. Les réseaux chimiques de polymères fixés de manière covalente sur des substrats solides plans ont été synthétisés par une approche polyvalente et facile à mettre en œuvre en utilisant la chimie click thiol-ène. Elle consiste à déposer des polymères préformés et réactifs en présence des réticulants dithiol sur des substrats modifiés thiol, la réaction de thiol-ène permettant la réticulation simultanée entre chaînes et le greffage en surface. La stratégie CLAG (Cross-Linking And Grafting) donne des films d'hydrogel chimiquement stables et reproductibles avec une large gamme d'épaisseur et avec les propriétés thermostimulables désirées. Les polymères hydrophiles fonctionnalisés par des groupes fonctionnels alcène peuvent être synthétisés en utilisant une copolymérisation radicalaire du monomère souhaité avec du méthacrylate d'allyle dans un solvant organique ou un co-solvant avec de l'eau. Une autre voie est la synthèse dans l'eau en deux étapes: le monomère désiré est copolymérisé avec l'acide acrylique puis le copolymère est modifié par l’allylamine. Trois familles de polymères ont été étudiées: poly(PEGMA), poly(acrylamide) et poly(zwitterion). La température de transition des films d'hydrogel est déterminée en mesurant l'épaisseur dans des solutions aqueuses par ellipsométrie. Les films d'hydrogel de poly(PEGMA) montrent des propriétés de LCST avec la température de transition augmentant avec le nombre d'unités de PEG. La LCST varie de 15°C à 60°C avec deux à cinq unités de PEG dans les chaînes pendantes. La LCST peut également être ajustée en utilisant des copolymères avec différents ratios. Les films d'hydrogel acrylamide ont à la fois des propriétés LCST et UCST. Les films d'hydrogel de poly(sulfobetaïne) montrent un comportement UCST très intéressant en plus d’être « anti-fouling », ce qui est très prometteur pour les applications en biologie.

Temperature-responsive surface-attached hydrogel thin films with various LCST/UCST (Lower/Upper Critical Solution Temperature) were designed for specific applications. The chemical polymer networks covalently attached on plane solid substrates were synthesized by a versatile and straightforward approach using thiol-ene click chemistry. It consists in coating ene-reactive polymers and dithiol crosslinkers on thiol-modified substrates, the thiol-ene click reaction allowing simultaneous cross-linking between chains and grafting on the surface. The CLAG (Cross-Linking And Grafting) strategy provides chemically stable and reproducible hydrogel films with a wide range of thickness and with the desired temperature-responsive properties. Ene-functionalized hydrophilic polymers can be synthesized using free radical copolymerization of the desired monomer with allyl methacrylate in organic solvent or co-solvent with water. Another way is the synthesis in water in two steps: the desired monomer is copolymerized with acrylic acid and then the copolymer is post-modified by amidification. Three polymer families were investigated: poly(PEGMA), poly(acrylamide) derivatives and poly(zwitterions). The transition temperature of the hydrogel films is determined by measuring the thickness in aqueous solutions at different temperatures with ellipsometry. Poly(PEGMA) hydrogel films show LCST properties with the transition temperature increasing with the number of PEG units. The LCST ranges from 15 °C to 60 °C with two to five PEG units in the pendant chains. The LCST can also be adjusted using mixed copolymers hydrogel. Poly(acrylamide) derivatives hydrogel films have both LCST and UCST properties. Poly(sulfobetaine) hydrogel films show very interesting UCST behavior in addition to be anti-fouling, which is very promising for biology applications.; Les films minces d'hydrogels thermosensibles à propriétés LCST/UCST (Lower/Upper Critical Solution Temperature) avec des températures de transition variables ont été mis au point pour des applications spécifiques. Les réseaux chimiques de polymères fixés de manière covalente sur des substrats solides plans ont été synthétisés par une approche polyvalente et facile à mettre en œuvre en utilisant la chimie click thiol-ène. Elle consiste à déposer des polymères préformés et réactifs en présence des réticulants dithiol sur des substrats modifiés thiol, la réaction de thiol-ène permettant la réticulation simultanée entre chaînes et le greffage en surface. La stratégie CLAG (Cross-Linking And Grafting) donne des films d'hydrogel chimiquement stables et reproductibles avec une large gamme d'épaisseur et avec les propriétés thermostimulables désirées. Les polymères hydrophiles fonctionnalisés par des groupes fonctionnels alcène peuvent être synthétisés en utilisant une copolymérisation radicalaire du monomère souhaité avec du méthacrylate d'allyle dans un solvant organique ou un co-solvant avec de l'eau. Une autre voie est la synthèse dans l'eau en deux étapes: le monomère désiré est copolymérisé avec l'acide acrylique puis le copolymère est modifié par l’allylamine. Trois familles de polymères ont été étudiées: poly(PEGMA), poly(acrylamide) et poly(zwitterion). La température de transition des films d'hydrogel est déterminée en mesurant l'épaisseur dans des solutions aqueuses par ellipsométrie. Les films d'hydrogel de poly(PEGMA) montrent des propriétés de LCST avec la température de transition augmentant avec le nombre d'unités de PEG. La LCST varie de 15°C à 60°C avec deux à cinq unités de PEG dans les chaînes pendantes. La LCST peut également être ajustée en utilisant des copolymères avec différents ratios. Les films d'hydrogel acrylamide ont à la fois des propriétés LCST et UCST. Les films d'hydrogel de poly(sulfobetaïne) montrent un comportement UCST très intéressant en plus d’être « anti-fouling », ce qui est très prometteur pour les applications en biologie.