Electrografting of mixed organophosphonic monolayers for SI-ATRP of 2-methacryloyloxyethyl phosphorylcholine

International audienceNitinol (NiTi), one of the most important alloys for biomedical applications, is still hampered by its surface nickel inclusions, making it sensitive to pitting corrosion and leading therefore to the release of potentially carcinogenic Ni2+ ions. In this work, we assess the impact of the combination of electrografted mixed self-assembled monolayers (SAMs) on NiTi followed by a polymer coating formed by surface-initiated atom transfer radical polymerization (SI-ATRP). The molecular ratio of 11-(2-bromoisobutyrate)-undecyl-1-phosphonic acid (BUPA) to 11-decylphosphonic acid (C10P) on the electroassisted elaboration of the (BUPA/C10P)-NiTi-SAMs has been optimized. A small amount of BUPA (20%) appears to be the most promising condition, as it provides an efficient corrosion resistance and promotes the SI-ATRP of 2-methacryloyloxyethyl methacrylate (MPC). This confers to the surface hydrophilic properties and corrosion resistance close to those NiTi-SAMs when long polymerization times are used (≥ 6 h)

TAD click chemistry on aliphatic polycarbonates : a first step toward tailor-made materials

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Preparation of well-defined poly[ethylene oxide-b-(sodium 2-acrylamido-2-methyl-1-propanesulfonate)] diblock copolymers by water-based atom transfer radical polymerization

peer reviewedWell-defined poly[(ethylene oxide)-block-(sodium 2-acrylamido-2-methyl-1-propane sulfonate)] diblock copolymers [P(EOm-b-AMPSn)], have been obtained by water-based ATRP using a-methoxy-?-(2-methylbromoisobutyrate) poly(ethylene oxide)s (MeO-P[EO]m-BriB with m ranging from 12 to 113) and CuBr?·?2Bpy (Bpy for 2,2'-bipyridyl) as macroinitiator and catalytic complex, respectively. Compared to direct polymerization in water, it has been demonstrated that the water/methanol (3:1, v/v) mixture is better suited for predicting the final number-average molar mass from the initial monomer-to-macroinitiator molar ratio and achieving a quite narrow polydispersity, even at high monomer conversion (?˜?1.4 at 80% conversion). The effect of temperature, solvent mixture composition and addition of NaCl salt on the polymerization rate and extent of control over the copolymer molecular parameters have been highlighted as well

A comparative study of the electro-assisted grafting of mono and bi-phosphonic acids on nitinol

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Advanced pH-responsive copolymer structures by combination of 'click' chemistry and atom transfer radical polymerization

peer reviewedIn this paper, the combination of atom transfer radical polymerization (ATRP) of 1-ethoxyethyl acrylate (EEA) and the copper(I) catalyzed ''click' 1,3-dipolar cycloaddition reaction of azides and terminal alkynes was evaluated as a method to synthesize diverse amphiphilic copolymer structures. Using the 1-ethoxyethyl protecting group strategy, the application field was broadened with the synthesis of complex polymer structures containing poly(acrylic acid) (PAA) segments. A modular approach has been used: polymers with alkyne functionalities as well as azide functionalities have been synthesized. These polymers were subsequently ''clicked' together to yield block copolymers. Furthermore, graft copolymers were synthesized by grafting alkyne-containing polymers onto a polymer backbone with multiple azide functions using the combination of ATRP and ''click' reactions

Polyelectrolyte complexes based on (quaternized) poly[2-dimethylamino)ethyl methacrylate] : behaviour in contact with blood

peer reviewedPolyelectrolyte complexes (PECs) between (quaternized) poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) and (crosslinked) N-carboxyethylchitosan (CECh) or poly(2-acrylamido-2-methylpropane sodium sulfonate) (PAMPSNa) were prepared and characterized in terms of their stability, equilibrium water content, and surface morphology. The evaluation of the behavior of the studied PECs in contact with blood revealed that the (crosslinked) CECh/(quaternized) PDMAEMA complexes had lost the inherent PDMAEMA cytotoxicity but still preserved haemostatic activity. In contrast, the complex formation between (quaternized) PDMAEMA and PAMPSNa allowed the preparation of materials with improved blood compatibility

One-pot synthesis of well-defined amphiphilic and adaptative block copolymers via versatile combination of 'click' chemistry and ATRP

peer reviewedWell-defined amphiphilic PCL-b-PDMAEMA block copolymers were successfully synthesized by a combination of ATRP and 'click' chemistry following either a commutative two-step procedure or a straightforward one-pot process using CuBr?·?3Bpy as the sole catalyst. Compared to the traditional coupling method, combining ATRP and click chemistry even in a 'one-pot' process allows the preparation of PCL-b-PDMAEMA diblock copolymers characterized by a narrow molecular weight distribution and quantitative conversion of azides and alkynes into triazole functions. Moreover, the amphiphilic character of these copolymers was demonstrated by surface tension measurements and critical micellization concentration was calculated

Controlled synthesis of amphiphilic block copolymers based on polyester and poly(amino methacrylate): comprehensive study of reaction mechanisms

peer reviewedThe synthesis of amphiphilic and adaptative block copolymers has been envisioned following a commutative two-step strategy involving atom transfer radical polymerization (ATRP) and the Huisgen-1,3-dipolar cycloaddition techniques. The reliability of this strategy is based on the use of an azido-containing ATRP initiator, the 2-(2-azidoethoxy)ethylbromoisobutyrate (N3EiBBr), able to be 'clicked' to an alkyne-terminated derivative and to promote the ATRP polymerization from the active site. In the context of this work, an alkyne-terminated poly(e-caprolactone) produced by ring-opening polymerization (ROP) of CL was employed as hydrophobic 'clickable' segment. The N3EiBBr initiator was obtained by nucleophilic substitution of the chloride atom from 2-(2-chloroethoxy)ethanol by an azide function and followed by the esterification of the hydroxy function by bromoisobutyryl bromide. This initiator was employed in polymerization of N,N-dimethylamino-2-ethyl methacrylate (DMAEMA) monomer by ATRP in THF at 60 °C using CuBr complexed by 1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETA) as catalytic complex. Low initiation efficiencies were obtained and they were ascribed to intramolecular cyclization during the polymerization as evidenced by ESI-MS and 2D NMR spectroscopy. The 'Click' coupling reaction was performed in THF at r.t. and was found to be efficient when using CuBr complexed by 2,2'-bipyridine ligand. To circumvent the low initiation efficiency, the N3EiBBr could be 'clicked' in a first step to PCL precursors before initiating the polymerization of DMAEMA monomer by ATRP. In this context, various catalytic complexes in different composition ratio were employed to optimize the 'click' coupling step. Moreover, this strategy was found to be suitable to produce well-defined PCL-b-PDMAEMA block copolymers, characterized by narrow polydispersity indices. Since ATRP and the Huisgen-1,3-dipolar cycloaddition both require the use of a copper(I)-based catalyst, the two first strategies were merged in a 'one-pot' process in order to obtain in one step a well-defined block copolymer characterized by a narrow polydispersity index and predictable composition and block lengths

Exploring the versatility of hydrogels derived from living organocatalytic ring-opening polymerization

peer reviewedIn this work we have bridged the use of mild and living organocatalytic ring-opening polymerization to facilitate the synthesis of cross-linked networks with an emphasis on hydrogels. Amidine-catalyzed ring-opening polymerization of bis-carbonate macromonomers in the presence of an alcohol provides the onset for the reaction and various building blocks issued from the initiator, macromonomer and comonomer can be used in different proportions to tailor the swelling behavior and mechanical integrity of final networks. Easy modifications of the building blocks additionally allow for finely tuning the hydrogel functionality and/or promoting responsiveness in the final structure

Synthesis of well-defined hydrogel networks using Click chemistry

peer reviewedNew PEG-based hydrogel materials have been synthesized by Click chemistry and shown to result in well-defined networks having significantly improved mechanical properties; the selectivity of the azide/acetylene coupling reaction also allows for the incorporation of various additives and functional groups leading to chemical tailoring of the hydrogels