One-pot controlled synthesis of double thermoresponsive N-vinylcaprolactam-based copolymers with tunable LCSTs

in Polymer Chemistry (2013), 4(8), 2575-2583

N-Vinylcaprolactam (NVCL) was copolymerized statistically for the first time in a controlled manner with hydrophilic N-vinylamide or hydrophobic vinylester monomers in order to precisely tune up and down ... [more ▼]

N-Vinylcaprolactam (NVCL) was copolymerized statistically for the first time in a controlled manner with hydrophilic N-vinylamide or hydrophobic vinylester monomers in order to precisely tune up and down the lower critical solution temperature (LCST) of the resulting copolymers. The incorporation of these segments in complex architectures was also considered. Several narrowly distributed NVCL-based copolymers were prepared by cobalt-mediated radical polymerization (CMRP) using the bis-(acetylacetonato)cobalt(II) complex as a controlling agent and N-methyl-N-vinylacetamide (NMVA), N-vinylacetamide (NVA), vinyl acetate (VAc) or vinyl pivalate (VPi) as comonomers. PNVCL-containing block copolymers having two discrete LCSTs were also synthesized following a one-pot strategy based on the sequential CMRP of NVCL followed by the copolymerization of NMVA with the residual NVCL. Upon gradual heating of aqueous solutions of such double thermoresponsive copolymers, we noticed a transition from free chains to micelles before full dehydration and collapse of the block copolymers. These advances represent a significant step towards the development of a platform based on thermoresponsive PNVCL copolymers with a single phase separation or multistep assembly behaviors. [less ▲]

Catechols as versatile platforms in polymer chemistry

in Progress in Polymer Science (2013), 38(1), 236-270

Catechols represent an important and versatile building block for the design of mussel-inspired synthetic adhesives and coatings. Indeed, their ability to establish large panoply of interactions with both ... [more ▼]

Catechols represent an important and versatile building block for the design of mussel-inspired synthetic adhesives and coatings. Indeed, their ability to establish large panoply of interactions with both organic and inorganic substrates has promoted catechol as a universal anchor for surface modifications. In addition to its pivotal role in adhesive interfaces, the catechol unit recently emerged as a powerful building block for the preparation of a large range of polymeric materials with intriguing structures and fascinating properties. The importance of catechols as efficient anchoring groups has been highlighted in recent excellent reviews partly dedicated to the characterization of their adhesive mechanisms onto surfaces and to their applications. The aim of this paper is to review for the first time the main synthetic approaches developed for the design of novel catechol-based polymer materials. We will also highlight the importance of these groups as versatile platforms for further functionalization of the macromolecular structures, but also surfaces. This will be illustrated by briefly discussing some advanced applications developed from these catechol-modified polymers. The review is organized according to the chemical structure of the functionalized catechol polymers. Chapter 1 discusses polymers bearing catechols embedded into the polymer main chain. Chapter 2 focuses on the attachment of catechol moieties as pendant groups and Chapter 3 describes the different approaches for incorporation of the catechol unit at the extremity of well-defined polymers. [less ▲]

Functional nanogels as platforms for imparting antibacterial, antibiofilm, and antiadhesion activities to stainless steel

in Advanced Functional Materials (2012), 22(24), 5271-5282

In this work, long-term antibacterial, antiadhesion, and antibiofilm activities are afforded to industrial stainless steel surfaces following a green and bio-inspired strategy. Starting from catechol ... [more ▼]

In this work, long-term antibacterial, antiadhesion, and antibiofilm activities are afforded to industrial stainless steel surfaces following a green and bio-inspired strategy. Starting from catechol bearing synthetic polymers, the film cross-linking and the grafting of active (bio)molecules are possible under environmentally friendly conditions (in aqueous media and at room temperature). A bio-inspired polyelectrolyte, a polycation-bearing catechol, is used as the film-anchoring polymer while a poly(methacrylamide)-bearing quinone groups serves as the cross-linking agent in combination with a polymer bearing primary amine groups. The amine/quinone reaction is exploited to prepare stable solutions of nanogels in water at room temperature that can be easily deposited to stainless steel. This coating provides quinonefunctionalized surfaces that are then used to covalently anchor active (bio) molecules (antibiofi lm enzyme and antiadhesion polymer) through thiol/ quinone reactions. [less ▲]

Cobalt-mediated radical (co)polymerization of vinyl chloride and vinyl acetate

in Polymer Chemistry (2012), 3(10), 2880-2891

The cobalt mediated radical polymerization (CMRP) of vinyl chloride (VC) in the presence of bis(acetylacetonato)cobalt(II) (Co(acac)2) as a controlling agent is presented for the first time. Using an ... [more ▼]

The cobalt mediated radical polymerization (CMRP) of vinyl chloride (VC) in the presence of bis(acetylacetonato)cobalt(II) (Co(acac)2) as a controlling agent is presented for the first time. Using an alkyl-Co(III) compound (R0–(CH2–CHOAc)<4–Co(acac)2; R0 = (H3C)2(OCH3)C–CH2–C(CH3)(CN)–) as an initiator, the bulk polymerization under non-isotherm conditions is controlled. 1H NMR spectra of the resulting PVC show that the CMRP process does not significantly affect the level of defects compared to a PVC prepared by a conventional free radical polymerization at the same temperature. Using the same alkyl-cobalt(III) compound, the copolymerization of VC and VAc is controlled at 40 °C provided that enough VAc (about 40 mol%) is present in the polymerization medium to moderate the VC polymerization. In line with reactivity ratios, VC is preferentially incorporated in the polymer at the early stages of the polymerization, leading to copolymers with a high VC content at moderate conversions. This is the first report of a CMRP of VC and of the synthesis of well-defined statistical PVC-co-PVAc copolymers by this technique. [less ▲]

Mechanistic investigation and selectivity of the grafting onto C60 of macroradicals prepared by cobalt-mediated radical polymerization

in Polymer (2012), 53(20), 4353-4358

The grafting mechanism of poly(vinyl acetate) macroradicals prepared by cobalt-mediated radical polymerization onto C60 is investigated. The experimental conditions directly impact the nature and ... [more ▼]

The grafting mechanism of poly(vinyl acetate) macroradicals prepared by cobalt-mediated radical polymerization onto C60 is investigated. The experimental conditions directly impact the nature and stability of the PVAc/C60 adducts. In the presence of residual initiating radicals that can compete with PVAc! macroradicals for addition onto C60, mixtures of PVAc/C60 adducts having between one and eight polymer chains per C60 are formed. PVAc/C60 adducts prepared with low [PVAc]:[C60] ratios may contain weak C60-C60 bonds that further dissociate and account for the instability of the products. The formation of such dimers can be lessened by increasing the temperature from 30 !C to 100 !C. The temperature increase also allows a complete dissociation of the PVAc-Co dormant species into PVAc! macroradicals and an almost quantitative grafting of eight PVAc chains onto C60, leading to well-de!ned C60(PVAc)8 octa-adducts. These results might shed new light on the grafting onto C60 of macroradicals prepared by other CRP techniques. [less ▲]

SINGLE-MOLECULE AFM STUDY OF ADHESIVE POLYMERS PREPARED BY COBALT-MEDIATED RADICAL POLYMERIZATION AND NITRONE-MEDIATED RADICAL COUPLING

Scientific conference (2012, September 10)

Well-defined poly(vinyl acetate) (PVAc) chains prepared by CMRP (cobalt-mediated radical polymerization) were coupled using an alkyne-functional nitrone via NMRC (nitrone-mediated radical coupling).1 In ... [more ▼]

Well-defined poly(vinyl acetate) (PVAc) chains prepared by CMRP (cobalt-mediated radical polymerization) were coupled using an alkyne-functional nitrone via NMRC (nitrone-mediated radical coupling).1 In all the cases, the coupling efficiencies were close to 90% or higher. The polymers mid-chain functionalized with an alkyne group were then reacted with azide-functionalized atomic force microscopy (AFM) tips via copper-catalyzed azide-alkyne cycloaddition (CuAAC). As a result, polymers having a double-branch architecture were linked to AFM tips via a short linker. The structure and the molecular parameters of the polymers were determined by NMR and GPC, whereas the ‘click’ step onto AFM tips was assessed by performing the same CuAAC reaction onto macroscopic surfaces and characterizing them by ATR FT-IR. The adhesive properties of these double-branched polymers were studied by AFM single-molecule force spectroscopy. By performing approach-retraction cycles in solution upon a glass surface, the interaction between single PVAc chains and the surface was investigated. The effect of the double-branch architecture on the adhesion forces was under focus. Setting a residence time of the tip on the surface before retraction was found to have a beneficial influence on the adhesion forces. Signs of multiple interactions acting in parallel were detected in the experimental force-distance traces. [less ▲]

Organometallic-mediated radical polymerization of vinyl amides: Effect of metal coordination

Conference (2012, September 04)

A green and bio-inspired process to afford durable anti-biofilm properties to stainless steel

in Biofouling (2012), 28(7), 719-728

A bio-inspired durable anti-biofilm coating was developed for industrial stainless steel (SS) surfaces. Two polymers inspired from the adhesive and cross-linking properties of mussels were designed and ... [more ▼]

A bio-inspired durable anti-biofilm coating was developed for industrial stainless steel (SS) surfaces. Two polymers inspired from the adhesive and cross-linking properties of mussels were designed and assembled from aqueous solutions onto SS surfaces to afford durable coatings. Trypsin, a commercially available broad spectrum serine protease, was grafted as the final active layer of the coating. Its proteolytic activity after long immersion periods was demonstrated against several substrata, viz. a synthetic molecule, N-a-benzoyl-DL-arginine-p-nitroanilide hydrochloride (BAPNA), a protein, FTC-casein, and Gram-positive biofilm forming bacterium Staphylococcus epidermidis. [less ▲]

Interpolymer radical coupling: A toolbox complementary to controlled radical polymerization

in Progress in Polymer Science (2012), 37(7), 1004-1030

The current review focuses on the relevance and practical benefit of interpolymer radical coupling methods. The latter are developing rapidly and constitute a perfectly complementary macromolecular ... [more ▼]

The current review focuses on the relevance and practical benefit of interpolymer radical coupling methods. The latter are developing rapidly and constitute a perfectly complementary macromolecular engineering toolbox to the controlled radical polymerization techniques (CRP). Indeed, all structures formed by CRP are likely to be prone to radical coupling reactions, which multiply the available synthetic possibilities. Basically, the coupling systems can be divided in two main categories. The first one, including the atom transfer radical coupling (ATRC), silane radical atom abstraction (SRAA) and cobalt-mediated radical coupling (CMRC), relies on the recombination of macroradicals produced from a dormant species. The second one, including atom transfer nitroxide radical coupling (ATNRC), single electron transfer nitroxide radical coupling (SETNRC), enhanced spin capturing polymerization (ESCP) and nitrone/nitroso mediated radical coupling (NMRC), makes use of a radical scavenger in order to promote the conjugation of the polymer chains. More than a compilation of macromolecular engineering achievements, the present review additionally aims to emphasize the particularities, synthetic potential and present limitations of each system. [less ▲]

Controlled radical polymerization of halogenated monomers

Patent (2012)

Process for the preparation of a halogenated polymer comprising a controlled radical polymerization step of at least one monomer containing at least one halogen-carbon bond, performed in the presence of ... [more ▼]

Process for the preparation of a halogenated polymer comprising a controlled radical polymerization step of at least one monomer containing at least one halogen-carbon bond, performed in the presence of an organo-cobalt complex, said polymerization step being further carried out in non-isotherm conditions. [less ▲]