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Surface- and Redox-Active Multifunctional Polyphenol-Derived Poly(ionic liquid)s: Controlled Synthesis and Characterization Nagaraj Patil,† Daniela Cordella,† Abdelhafid Aqil,† Antoine Debuigne,† Shimelis Admassie,‡,§ Christine Jérôme,*,† and Christophe Detrembleur*,† †

Centre for Education and Research on Macromolecules (CERM), CESAM Research Unit, Department of Chemistry, University of Liege, Allée de la Chimie B6A, 4000 Liège, Belgium ‡ Biomolecular and organic electronics, IFM, Linköping University, S-581 83 Linköping, Sweden § Department of Chemistry, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia S Supporting Information *

ABSTRACT: Combining the redox activity and remarkable adhesion propensity of polyphenols (such as catechol or pyrogallol) with the numerous tunable properties of poly(ionic liquid)s (PILs) is an attractive route to design inventive multifunctional macromolecular platforms. In this contribution, we describe the first synthesis of a novel family of structurally well-defined PILs functionalized with catechol/pyrogallol/phenol pendants by organometallic-mediated radical polymerization (OMRP) using an alkyl−cobalt(III) complex as initiator and mediating agent. The living character of the chains is also exploited to produce di- and triblock PILs, and the facile counteranion exchange reactions afforded a library of PILs-bearing free phenol/catechol/pyrogallol moieties. Electrochemical investigations of catechol/pyrogallolderived PILs in aqueous medium demonstrated the characteristic catechol to o-quinone transformations, whereas, quasireversible doping/undoping with supporting electrolyte cations (Li+/tetrabutylammonium+) has been observed in organic media, suggesting a bright future for this new family of redox-active PILs as cathode material for secondary energy storage devices. Also, pendant catechol/pyrogallol groups mediated sustained anchoring onto the gold surface conferred PILs properties to the interface. As a proof-of-concept, both the adsorption and inhibition of proteins on polymer modified surfaces have been demonstrated in real time using the quartz crystal microbalance with dissipation technique. The exquisite physicochemical tunability of these innovative surface- and redox-active PILs makes them excellent candidates for a broad range of potential applications, including “smart surfaces” and electrochemical energy storage devices.

1. INTRODUCTION

Most often, PILs are characterized by low volatility, relatively high ionic conductivity, and broad electrochemical stability window, making them promising solid-state electrolyte materials in a range of electrochemical usages.12 The incorporation of redox-active functional groups, such as ferrocene, metal complexes, nitroxides, or catechols, etc., in the PILs chain forms “redox-active PILs”, an emerging family of PILs of high interest for energy applications. As selected examples, some of them were explored as PILs-modified electrodes in molecular electronics, (bio)analytical sensors, electrochemical actuators, and energy transduction materials.14−19 These redox-active PILs were obtained either via postmodification of neutral polymer precursors14−17 or by direct polymerization of the functional monomer, protected or not, depending on the polymerization technique that was used for their production.18−20 For instance, when radical polymerization of redox-active IL monomer is considered, the

Poly(ionic liquid)s (PILs) represent a subclass of polyelectrolytes that features several intriguing properties, such as high ionic conductivity, tunable solubility, negligible vapor pressure, and excellent electrochemical and thermal stability, etc., derived from the combination of the properties of ionic liquids (ILs) and macromolecular architecture.1−8 This unique combination of properties and functions attracts a huge potential in a multitude of applications, including analytical chemistry, biotechnology, catalysis, electrochemical devices, and membrane technology.9−13 Although many types of PILs have been reported in the literature, the fundamental approach to synthesize them is through postmodification of existing polymers or by direct polymerization of IL monomers (ILMs). From a synthetic perspective, each of these strategies governs different structural parameters of PILs and demonstrates distinct advantages as well as limitations with respect to the molecular design. However, the latter strategy is conceptually simple and straightforward and is widely adopted when a high content of IL moieties is desired. © XXXX American Chemical Society

Received: August 26, 2016 Revised: September 21, 2016

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DOI: 10.1021/acs.macromol.6b01857 Macromolecules XXXX, XXX, XXX−XXX

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Macromolecules scavenging ability of catechol or nitroxide groups may cause inhibition and/or impede the radical polymerization and/or lead to side reactions (such as branching).21−24 The precision synthesis of PILs-bearing catechols by CRP therefore remains difficult. In order to avoid these side reactions, catecholprotecting group chemistry has been performed. Namely, only a few protecting agents, silyl,25 methoxy,26 and acetonide27 protecting groups, were successfully installed, and their CRP proceeded efficiently but exclusively for the preparation of nonionic (co)polymers. Additionally to its attractive redox properties, catechol is also largely used for designing synthetic bio-inspired glues28−30 and for the functionalization of surfaces with biomolecules like peptides and enzymes.31−35 Polymers bearing imidazolium moieties are among the most investigated PILs. They are mainly produced by polymerizing ILMs in the form of styrenic,36 or (meth)acrylic,37,38 or norbornenyl20 containing pendant imidazolium groups, featuring various counteranions (mainly Br−, BF4−, PF6−, and (CF3SO2)2N− = TFSI−), by means of either conventional or controlled polymerization techniques. Also, poly(1-vinyl-3alkylimidazolium)s (PVImX) represent an important class of those PILs that are commonly prepared by conventional radical polymerization and that present a broad electrochemical stability window.1−8 However, compared to styrenic or (meth)acrylic containing imidazolium, the controlled radical polymerization (CRP) of 1-vinyl-3-alkylimidazolium-type (VImX) IL monomers is less documented as the result of the high reactivity of their growing species. During the past decade substantial progress has been made in this direction by implementing the addition−fragmentation chain transfer (RAFT)39 and organometallic-mediated radical polymerization (OMRP)40−45 methods to VImX, consequently broadening the scope of PILs structures, functionalities, and applications. The CRP of VImX bearing redox-active groups like catechol or pyrogallol is however problematic and pose an additional challenge, unless proper protecting group chemistry is employed to mask them. A careful chemical manipulation, following pre- and post-CRP process, is expected to yield innovative well-defined, multifunctional, high-performance PILs, emanating from the combination of both functionalities, imidazolium and catechol/pyrogallol groups. In this contribution, we report the first precision synthesis of PILs bearing polyphenol by OMRP of novel VImX bearing pendant catechol/pyrogallol in their protected version, and unprotected phenol, mainly focusing on catechol functionalized ones. A neat and quantitative postpolymerization deprotection followed by facile anion exchange reaction affords a novel library of redox-active PILs, featuring various counteranions, and thus properties. Scheme 1 shows the structure and anticipated properties of these cationic polyelectrolytes that motivate their synthesis. The association of a redox-active and adhesive groups (catechol or pyrogallol) with imidazolium moiety on a very short −CH2−CH− backbone segment is the unique feature of these PILs, which is highly attractive for the function or performance of PILs that directly depends on the concentration/content of these functional groups in the macromolecule. For instance, in electrochemical energy storage devices, low molar mass of the repeating monomer unit accompanied by a multielectron exchange process with exquisite synergism of electronic/ionic conductivity, stemming from PILs and catechol groups, is anticipated. This synergy between imidazolium/catechol(pyrogallol) will be illustrated by

Scheme 1. General Structure and Anticipated Properties of Well-Defined Multifunctional Redox-Active Poly(ionic liquid)s

exploring the fundamental electrochemical behavior of these novel redox-active PILs. As another illustration of the multifunctionality of those PILs, combining a high charge density PILs and catechol(pyrogallol)-anchoring chemistry renders numerous relevant properties to a surface on which the PILs is deposited without requiring any surface preparation techniques. Here, the remarkable adhesion of catechol/ pyrrogallol21−27 pendant units facilitates the strong anchoring of PILs on a substrate, and the ionic feature of the polymer chain is exploited to avoid or enhance protein adsorption. To the best of our knowledge, this is the first report on the controlled synthesis of this novel family of multifunctional redox-active PILs by a controlled radical polymerization technique.

2. EXPERIMENTAL SECTION 2.1. Materials. 1-Vinylimidazole (≥99%, Sigma-Aldrich), thionyl chloride (≥99%, Sigma-Aldrich), and isoprene (≥99%, Sigma-Aldrich) were freshly distilled prior to use and stored under argon. 4-(2Hydroxyethyl)phenol (>98%, TCI), methyl 3,4-dihydroxybenzoate (>95%, fluorochem), methyl 3,4,5-trihydroxybenzoate (98%, SigmaAldrich), 2-chloro-1-(3,4-dihydroxyphenyl)ethan-1-one (95%, fluorochem), benzyl chloride (99%, Sigma-Aldrich), α,α-dichlorodiphenylmethane (97%, Sigma-Aldrich), thioanisole (≥99%, SigmaAldrich), hydrogen chloride solution (HCl, 4.0 M in dioxane, TCI), Pd/C, ammonium formate (≥99.9%, Sigma-Aldrich), 48% hydrobromic acid (HBr, Sigma-Aldrich), potassium carbonate (K2CO3, ≥99%, Sigma-Aldrich), lithium aluminum hydride (LiAlH4, 95%, Sigma-Aldrich), 2,2,6,6-tetramethylpiperidine-1-oxy (TEMPO, 98%, Sigma-Aldrich), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) (99%, ABCR), lithium hexafluorophosphate (LiPF6) (≥99.99%, Sigma-Aldrich), tetrabutylammonium bis(trifluoromethanesulfonyl)imide (TBA-TFSI) (≥99%, Sigma-Aldrich), bovine serum albumin (BSA) (≥98%, Sigma-Aldrich), and lysozyme from chicken egg white (Sigma-Aldrich) were used as received. Sodium bicarbonate (NaHCO3), anhydrous magnesium sulfate (MgSO4), and sodium chloride (NaCl) were of the highest grade, purchased from SigmaAldrich, and used without further purification. N,N-Dimethylformamide (DMF), tetrahydrofuran (THF), dichloromethane, ethyl acetate, methanol, toluene, chloroform and diethyl ether were dried using standard procedures, distilled, and stored under argon prior to use. Deuterated DMSO-d6, D2O, and methanol-d4 were purchased from Deutero GmbH. Membrane Spectra/Pore (MWCO: 3500 Da) was used for dialysis. Alkyl−cobalt(III) adduct (R-Co(acac)2) was synthesized and characterized following our previous publication46 and stored as a stock solution in CH2Cl2 at −20 °C under argon. 1-Vinyl3-ethylimidazolium bromide (VIm-et-Br) was synthesized following the reported procedure.40 The experimental procedure for the synthesis of 3-(3,4-bis(benzyloxy)benzyl)-1-vinyl-1H-imidazol-3-ium chloride (5, VIm-catⓅ-Cl), 3-(2-(2,2-diphenylbenzo[d][1,3]dioxol-5yl)-2-oxoethyl)-1-vinyl-1H-imidazol-3-ium chloride (8, VIm-catoⓅCl), 3-(3,4,5-tris(benzyloxy)benzyl)-1-vinyl-1H-imidazol-3-ium chloride (13, VIm-pyrⓅ-Cl), and 3-(4-hydroxyphenethyl)-1-vinyl-1Himidazol-3-ium bromide (16, VIm-phe-Br) monomers and their B


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reaction proceeds at 30 °C. After 2 h of predetermined reaction period (monomer conversion reached 80% conversion), the solution is divided in two portions: the first portion is quenched with a solution of TEMPO (0.2 mmol) in dried and degassed DMF, and the second portion is added by 0.2 mL of isoprene; the coupling reaction occurs at 30 °C overnight. 1H NMR analysis of coupling reaction aliquot confirmed that residual VIm-et-Br did not further polymerized during the coupling reaction. 2.5. General Procedure for the Deprotection of Polymers. A two-necked round-bottom flask was charged with 3.0 g of benzyl etherprotected polymer and evacuated by three consecutive vacuum−argon cycles. Degassed thioanisole (5 equiv for each benzyl ether group of monomeric unit in PVIm-catⓅ/pyrⓅ-Cl) was then transferred under an argon atmosphere, and the reaction mixture was ice-cooled to 0 °C, before adding dropwise 4.0 M HCl (2 equiv for each benzyl ether group) in dioxane. Upon addition, reaction was allowed to stir vigorously for 4 h under an argon atmosphere at 60 °C. Upon completion, the reaction medium was bubbled with argon to remove HCl, followed by evaporation under reduced pressure in a rotavapor to remove dioxane. The obtained residue was redissolved in methanol, dialyzed against degassed methanol for 2 days in order to remove excess of thioanisole and reaction byproducts, and dried under vacuum to obtain PVIm-cat/pyr-Cl as gray colored solids. Following a similar strategy, 4.0 M HCl in dioxane catalyzed methanolysis of PVIm-cat oⓅ-Cl in the presence of thioanisole resulted in successful deprotection of diphenyldioxole protecting groups. 2.6. Anion Metathesis. 2.0 mmol of poly(1-vinyl-3-alkylimidazolium) salt with halide counteranion (Br−/Cl−) was dissolved in 20 mL of degassed THF/deionized water (1:1, v/v %), followed by dropwise addition of 2.2 mmol of LiTFSI or LiPF6 in 5 mL of degassed water, and continued stirring under argon overnight at room temperature. THF was then removed under vacuum to provide an oily product in water that was then extracted with ethyl acetate and washed several times with deionized water (until no precipitate of AgCl is observed, upon testing with AgNO3 solution). Concentrated product was dried under vacuum to yield PILs with TFSI−/PF6− counteranion as a gray colored solid in quantitative yield. 2.7. Characterization Methods. 1H and 13C NMR spectra were recorded at 298 K with a Bruker 400 MHz spectrometer. The Fourier transform infrared (FTIR) spectra were recorded using Thermo Fisher spectrometer with an attenuated total reflectance (ATR) accessory by continuum microscope provided with an ATR germanium (Ge) crystal in the spectral range of 4000−550 cm−1 by accumulation of 64 scans with a nominal resolution of 4 cm−1. UV−vis studies were performed using a Hitachi spectrometer (U-3300) with a scan rate of 600 nm min−1. The thermogravimetric (TGA) measurements were performed at 10 °C min−1 with a TA TGA Q500 apparatus. Differential scanning calorimetric (DSC) analysis was performed on TA DSC Q100 thermal analyzer calibrated with indium, at a heating/cooling rate of 10 °C min−1, under a flowing nitrogen atmosphere with a sample weight of ∼10 mg. The glass transition temperature (Tg, reported for the third heating cycle) was determined using the onset method, defined as the midpoint of the intersection between the onset and the midpoint with the offset and the midpoint tangent lines, using TA analysis software provided with the instrument. The polymer relative number-average molar mass (Mn,SEC) and molar mass distribution (Đ) measurements were carried out by size exclusion chromatography (SEC) in a THF containing 10.0 mM lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) solution (flow rate: 1 mL min−1) at 35 °C, using a SFD S5200 autosampler liquid chromatograph equipped with a SFD refractometer index detector 2000.47 A PSS SDV analytical linear S 5 μm column (molar mass range: 100−150 000 Da), protected by a PL gel 5 μm guard column, was calibrated with poly(styrene) standards. Polymer samples containing Cl−/Br− were exchanged for TFSI− counteranion prior to SEC analysis according to the following procedure. 2 mL of THF and deionized water (1:1, v/v %) was added in each sample (15−20 mg), and the solutions were stirred for 5 min. After adding an excess of LiTFSI (50−60 mg), the sample was left under stirring overnight. The polymer solution was precipitated (×3) in deionized water in order to

intermediates is described in the Supporting Information. The symbol Ⓟ implies that monomers (and their polymers) bearing pendant catechol (5) and pyrogallol (13) moieties were protected in the form of a benzyl ether. The catechol functionality in monomer 8 was also installed with diphenyldioxole-type protecting group. 2.2. Typical Procedure for the Homopolymerization of 1Vinyl-3-alkylimidazolium (VImX)-Type Monomers. All polymerization reactions were performed under argon using standard Schlenk techniques. A typical homopolymerization of VImX monomer with a [monomer]:[R-Co(acac)2] ratio of 75:1 is described as follows: A 100 mL of one-necked round-bottom flask was flame-dried and charged with 10.0 mmol of monomer, dried overnight under vacuum at ambient temperature, and degassed by three consecutive vacuum/ argon cycles. 50 mL of degassed anhydrous DMF was then added under argon to solubilize the monomer and ice-cooled to 0 °C. A solution of R-Co(acac)2 in CH2Cl2 (1 mL, 0.13 M, 0.13 mmol) was introduced under argon into a second 100 mL one-necked roundbottom flask, and the solvent was evaporated under reduced pressure. The monomer solution in DMF was then transferred under argon by cannula into the flask containing R-Co(acac)2 under stirring at 0 °C. Approximately 0.25 mL of reaction mixture was taken out at regular time intervals to determine the number-average molar mass (Mn,SEC), molar mass distribution (Đ) by SEC (after counteranion exchange as described below in the Characterization Methods section), and monomer conversion by 1H NMR spectroscopy. The polymerization reaction was stopped at predetermined time periods, quenching immediately by adding a solution of TEMPO (0.65 mmol) in degassed DMF. The residual monomer, Co(acac)2, and excess of TEMPO were removed by dialysis against methanol (MWCO: 3500 Da) and dried under vacuum at room temperature overnight to obtain a cream colored solid. 2.3. A Representative P(VIm-pyrⓅ-Cl)-b-P(VIm-et-Br) Diblock Copolymer Synthesis. A typical procedure for the synthesis of P(VIm-pyrⓅ-Cl)-Co(acac)2 and subsequent chain extension by VImet-Br to obtain P(VIm-pyrⓅ-Cl)-b-P(VIm-et-Br) diblock copolymer is described as follows: VIm-pyrⓅ-Cl (0.5 g, 0.93 mmol) was introduced in a Schlenk tube and dried overnight under vacuum. The tube was evacuated by three consecutive vacuum−argon cycles and backfilled with argon, before transferring 5 mL of degassed anhydrous DMF using cannula under argon to solubilize the monomer. A solution of RCo(acac)2 in CH2Cl2 (0.15 mL, 0.13 M, 0.018 mmol) was introduced under argon into a second Schlenk tube, and the solvent was evaporated under reduced pressure. The monomer solution in DMF was then transferred under argon by cannula into the flask containing R-Co(acac)2 under stirring at 0 °C for 1.5 h. A sample is withdrawn to determine the monomer conversion by 1H NMR (90% conversion) and the molecular characteristics of the polymer by SEC after anion exchange with LiTFSI. The solution of the second monomer in degassed anhydrous DMF (0.2 g of VIm-et-Br in 2 mL of DMF) was then added under argon to the solution of the first P(VIm-pyrⓅ-Cl)Co(acac)2 block, and the reaction proceeds for 2 h at 30 °C. The growth of second block was monitored by picking out approximately 0.25 mL of reaction aliquot at regular time intervals to determine the monomer conversion by 1H NMR and the molecular characteristics of the polymer by SEC. The polymerization reaction was stopped at predetermined time period, quenched by adding TEMPO, and purified as described above. 2.4. A Representative P(VIm-pyrⓅ-Cl)-b-P(VIm-et-Br)-b-P(VIm-pyrⓅ-Cl) Triblock Copolymer Synthesis. A typical procedure for the synthesis of P(VIm-pyrⓅ-Cl)-Co(acac)2 and subsequent chain extension by VIm-et-Br followed by cobalt-mediated radical coupling (CMRC) to obtain symmetric P(VIm-pyrⓅ-Cl)-b-P(VIm-etBr)-b-P(VIm-pyrⓅ-Cl) triblock copolymer is described as follows: The homopolymerization of VIm-pyrⓅ-Cl (0.5 g, 0.93 mmol) using RCo(acac)2 in CH2Cl2 (0.15 mL, 0.13 M, 0.018 mmol) proceeds in anhydrous DMF at 0 °C, as described above. Once a near-quantitative monomer conversion is reached (91% in 1.5 h, as determined by 1H NMR), the solution of the second monomer, VIm-et-Br (0.2 g, 0.98 mmol), in 2 mL of degassed anhydrous DMF was injected into the solution of the first P(VIm-pyrⓅ-Cl)-Co(acac)2 block, and the C


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Scheme 2. Synthesis of VIm-catⓅ-Cl (5) and VIm-pyrⓅ-Cl (13) Monomers from 3,4,(5)-Di(tri)hydroxybenzoate (1, 9)-Type Precursora

a Reagents and conditions: (i) BnCl, K2CO3, DMF, 75 °C, 12 h; (ii) LiAlH4, THF, 2 h; (iii) SOCl2, cat. DMF, DCM, 4 h; (iv) 1-vinylimidazole, THF, 70 °C, 48 h.

remove the residual LiCl/LiBr, solubilized in THF containing LiTFSI (10.0 mM), and filtered two times with nylon membrane filter (size 0.45 and 0.20 μm, respectively). 2.8. Electrochemical Analysis. Cyclic voltammetry (CV) measurements were carried out in both aqueous and anhydrous organic (DMSO) media containing 0.1 M acetate buffer (pH 3.5) and 0.1 M LiTFSI/TBA-TFSI supporting electrolyte, respectively, using the standard three-electrode configuration where a platinum wire and a glassy carbon electrode (GC, with an area of 0.07 cm2) were used as counter (CE) and working electrodes, respectively (Bioanalytical Systems Inc. USA). An Ag/AgCl (KCl sat.) and Ag/AgNO3 in CH3CN 0.1 M n-Bu4NPF6 were used as reference (RE) electrode in aqueous and organic media, respectively. All electrolytes were degassed with dry nitrogen, and voltammograms were recorded using Autolab PGSTAT 10 (EchoChemie, The Netherlands) under a nitrogen atmosphere at room temperature. 2.9. Quartz Crystal Microbalance with Dissipation (QCM-D). Real-time adsorption of bovine serum albumin (BSA) and lysozyme proteins onto naked and polymer immobilized gold surfaces was studied by the QCM-D technique using a Q-Sense E4 system (QSense AB, Sweden). Gold AT-cut resonators (0.3 mm thickness, 14 mm diameter, fundamental resonant frequency of 4.95 MHz and its 3rd, 5th, 7th, 9th, 11th, and 13th overtones, n, which correspond to resonance frequencies of 14.85, 24.75, 34.65, 44.55, 54.45, and 64.35 MHz, respectively) were transferred to a standard Q-Sense flow module (QFM 401) and equilibrated with PBS buffer (pH 7.4) to obtain a stable baseline. A constant flow rate of 200 μL min−1 and constant temperature of 25 ± 0.02 °C were used for all the experiments. The monitored frequency shift (Δf) and dissipation shift (ΔD) parameters were used to gain insight into the nature of adsorption (rigid/soft), whereas the Sauerbrey relationship was then employed to quantify the mass of rigid adlayer. For clarity purposes, the number of data points (raw Δf and ΔD plots) was reduced, using smoothing and decimation options in OriginPro 9.0 software.

Scheme 3. Synthesis of VIm-catoⓅ-Cl (8) Monomer from 2-Chloro-1-(3,4-dihydroxyphenyl)ethan-1-one (6)a

Reagents and conditions: (i) α,α-dichlorodiphenylmethane, toluene, 170 °C, 12 h; (ii) 1-vinylimidazole, MeOH, 70 °C, 48 h. a

monomer VIm-phe-Br (16) was synthesized from 4-(2hydroxyethyl)phenol (14) precursor (Scheme 4). Scheme 4. Synthesis of VIm-phe-Br (16) Monomer from 4(2-Hydroxyethyl)phenol (14)a

3. RESULTS AND DISCUSSION 3.1. Synthesis of Monomers. The general outline for the synthesis of monomers VIm-catⓅ-Cl (5), VIm-pyrⓅ-Cl (13), and VIm-catoⓅ-Cl (8) is presented in Schemes 2 and 3. The detailed synthetic approach, including experimental conditions, yield, etc., along with schemes (Schemes S1−S3) is given in the Supporting Information. Two different inexpensive commercially available synthons 3,4-dihydroxybenzoate (1) and 2chloro-1-(3,4-dihydroxyphenyl)ethan-1-one (6) were considered for the synthesis of catechol functionalized monomers in their protected version. The benzyl ether protected monomer VIm-pyrⓅ-Cl (13) was synthesized using methyl 3,4,5trihydroxybenzoate (9) as a starting material (source of pendant pyrogallol). The unprotected pendant phenol

Reagents and conditions: (i) HBr, 85 °C, 12 h; (ii) 1-vinylimidazole, MeOH, 80 °C, 36 h.

a

The proper protection of catechol/pyrogallol functional units is prerequisite in order to circumvent their aforementioned chemical reactivity, hence enabling further chemical manipulations. Among various protecting groups, benzyl ether protecting group chemistry has been extensively practised to mask amino and hydroxyl functionalities, which can be neatly and more conveniently cleaved upon catalytic hydrogenolysis or acidolysis using strong acids.48 These attracting features, including their low cost, ease of formation, and stability under a variety of reaction conditions, encouraged us to protect D


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Macromolecules Scheme 5. Routes toward the Polyelectrolytes Bearing Phenol, Catechol, or Pyrogallol with Different Counteranions

with the hydrophobic TFSI− counteranion, as described in the Supporting Information. While the melting temperatures (Tm) of the four monomers, VIm-catⓅ-Cl (5), VIm-catoⓅ-Cl (8), VIm-pyrⓅ-Cl (13), and VIm-phe-Br (16), are higher than 100 °C (Figure S25), all the monomers with TFSI− counteranion exhibit melting points below 100 °C (Figure S25). According to the common notion of ionic liquids (ILs), the monomers with TFSI− as counteranion can therefore be considered as a new family of IL monomers.1−8 3.2. Synthesis of Polyphenol-Derived Poly(ionic liquid)s by OMRP. Scheme 5 illustrates the synthetic route toward the polyelectrolytes bearing phenol, catechol, or pyrogallol pendant groups with different counteranions. All polymerizations were quenched by the addition of excess TEMPO to avoid side reactions during polymer purification, according to the reported procedures.40−45 3.2.1. OMRP of VIm-catⓅ/catoⓅ/pyrⓅ-Cl and VIm-pheBr Monomers. The OMRP of 1-vinyl-3-alkylimidazolium (VImX)- type IL monomers using preformed alkyl−cobalt adduct (R-Co(acac)2) has been proven to be an efficient way to obtain PILs in a controlled fashion. 40−45 The initial optimization through R-Co(acac)2-mediated OMRP of VImcatⓅ-Cl using a monomer/R-Co(acac)2 molar ratio of 75:1 in DMF at 30 °C was extremely fast, reaching a high monomer conversion (∼98%) in few minutes ( PF6− > Br−,71 attributed to reverse trend in their nucleophilicity/proton-abstracting natureone of the main thermal

Figure 8. Cyclic voltammograms of (A) PVIm-cat-TFSI, (B) PVImpyr-TFSI, and (C) PVIm-phe-TFSI drop-casted films in 0.1 M acetate buffer (pH 3.5) at a glassy carbon electrode. Scan rate = 100 mV s−1.

casted film) at glassy carbon electrode in aqueous solution containing 0.1 M acetate buffer (pH 3.5). The voltammogram shows a single redox process with the average peak potentials E1/2 ([Ep,a + Ep,c]/2) located at 0.48 V vs Ag/AgCl, corresponding to an anodic peak (Ep,a) of 0.65 V (8A(A1)) and a cathodic peak potential (Ep,c) of 0.32 V, 8A(C1). These redox peaks corresponds to the transformation of catechol to oquinone and vice versa within a quasi-reversible proton-coupled two-electron process.79 The electrochemical behavior of pendant pyrogallol units in PVIm-pyr-TFSI was similar to that of PVIm-cat-TFSI. However, E1/2 corresponding to the QH2/Q-RC in PVIm-pyr-TFSI has occurred at more cathodic potential (ca. 0.31 V) compared to the same redox process in PVIm-cat-TFSI (Figure 8B), owing to the presence of an additional −OH group on the position 5 of the aromatic ring.58 In the case of the PVIm bearing pendant phenols, PVIm-pheTFSI, the occurrence of an anodic peak (8C(A1) = Ep,a = 1.1 J


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Figure 9. Cyclic voltammograms of PVIm-cat-TFSI (A) 10.0 mM of monomer unit in solution and (B) drop-casted film at a glassy carbon electrode in DMSO containing 0.1 M LiTFSI at various scan rates.

respectively, with increasing scan rates, the linear proportionality of peak currents with the square root of the scan rate (S46A, Supporting Information), and b ≈ 0.55 for HQ•+/Q and b ≈ 0.45 for Q•−/Q2− (S46B, Supporting Information) indicate that diffusion process in PVIm-cat-TFSI is an important factor in controlling the electrochemical behavior of PVIm-cat-TFSI. A similar diffusion-controlled two successive one-electron irreversible redox process attributed to the catechol/o-quinone transformation was observed for PVImpyr-TFSI in DMSO solution containing 0.1 M LiTFSI (Figures S47−S48). In contrast to the solution system, the CV curves of the PVIm-cat/cato/pyr-TFSI films in DMSO, containing 0.1 M tetrabutylammonium bis(trifluoromethanesulfonyl)imide (TBA-TFSI) supporting electrolyte, in which the stability of ion-pair complexes between the catechol (di)anions and TBA+ cations is least, exhibit two successive one-electron quasireversible redox processes, which is attributed to the n-doping/ n-undoping reactions (Figures S49−S50). The electrochemical behavior of the Q/Q2− process for the above-stated species in the given electrolyte system is largely similar, except their formal redox potentials, which are in accordance with their electronic structure of the redox units. Furthermore, PVIm-catTFSI drop-casted film at a glassy carbon electrode in DMSO containing 0.1 M LiTFSI at slow scan rates exhibits the formation of Q•− and Q2− species (Figure 9B) during the reduction processes at 9B(C1) and 9B(C2). This suggests the capture of Li+ to give the n-doped states (and corresponding nundoping peaks at 9B(A2, A1)), demonstrating an adsorption (surface-bound)-controlled two successive one-electron quasireversible84 process (Figure S51). This doping/undoping of the supporting electrolyte cations (H+, TBA+, Li+) into/from PVIm-cat/pyr-TFSI in the reduction/oxidation cycle is very encouraging for designing potential redox-active cathode materials in electrochemical secondary energy storage devices.76,77 The combination of IL and redox-active pendant groups in the same repeating unit is expected to (i) improve the ion conductivity in the electrode layer due to the high TFSI− counteranion mobility,1−8 which is often a limiting factor at high current densities (for power performance),87−89 and (ii) provide efficient binding between active-material, carbon additives (nanotube, reduced graphene oxide, etc.) and current collector, via their well-known cation−π90,91 and π−π92 interactions, respectively, for the fabrication of a binder-free electrode. The testing of the efficiency of this novel family of

V) in the forward scan (that corresponds to the oxidation of phenol moieties) with no indication of reduction peak in the reverse scan is in line with an irreversible process, as noted in the literature.80 The oxidation potentials measured by CV have been used to compare the antioxidant strength of polyphenols.59 Low oxidation potentials are associated with a greater facility or strength of a given molecule for the electrodonation and, thus, to act as antioxidant. An initial assessment of the CV results allowed us to predict the antioxidant strength of presented polyphenols; in the order of PVIm-pyr-TFSI > PVIm-cat-TFSI > PVIm-phe-TFSI.58 The detailed investigation of antioxidant ability of the presented polymers is beyond the scope of this article but is already very well documented in the literature.60 The electrochemical behavior of QH2/Q-RC in a number of traditional aprotic solvents has been extensively investigated.81−84 The electrochemistry of QH2/Q-RC in these media is complicated: reported to be an electrochemically irreversible two-electron process and is influenced by various factors such as the polarity of the solvent, the substituents on the benzene ring, and, more importantly, the cation of the supporting electrolyte.83 Figure 9A shows CV of PVIm-catTFSI (10.0 mM of monomer unit in DMSO) containing 0.1 M LiTFSI. Two successive one-electron irreversible oxidation peaks, 9A(A1; Q•+) and 9A(A2; Q) in the forward scan and reduction peaks, 9A(C1; Q•−) and 9A(C2; Q2−) in the reverse direction are accounted for QH2/Q and Q/Q2− redox process, respectively, as depicted chemically in 9A.84 The absence of reversible reduction peak corresponding to the QH2/Q transformation indicates that H+ released by the oxidation of QH2 cannot be recaptured by Q during the reduction process even at the slow scan rate of 16 mV s−1. However, Q•− and Q2− species formed at 9A(C1) and 9A(C2) seem to capture Li+ existing at high concentration instead of H+ to give the n-doped states. It is worth to mention here that among alkali metals, the formation of thermodynamically stabilized ion-pair complexes between o-radical anions or o-dianions of the compound under investigation and the cations of the supporting electrolyte is most significant with the Li+ cation and is further greatly amplified in o-dihydroxy isomers85,86 (as is the case here), thereby complicating the voltammogram in the present electrolyte system. Nevertheless, almost similar CV curves were obtained upon repeated cycling, suggesting that the polymer was stable in the solution and did not undergo complicated reactions. A slight shift in the anodic and cathodic peak potential toward the positive and negative directions, K


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rinsing step, demonstrating that the polymer adlayer strongly tethered onto the surface. On the other hand, poly(vinylimidazolium) bearing an ethyl chain, PVIm-et-Br42 (structure is shown in Figure 10), displayed an unsustained adherence toward gold surface, where a complete desorption upon rinsing step is observed, despite the initial deposition (Figure 10D). Therefore, catechol or pyrogallol functionalities in the described polymers can be foreseen as anchoring units, thereby imparting ILs properties to the surface and eliminating time-consuming addition multistep strategies as conventional methods demand. First, we have studied the adsorption of BSA and lysozyme onto gold surface and monitored Δf n/n and ΔDn vs time (Figures S52−S53). A quantitative treatment of Δf n/n and ΔDn QCM-D plots to obtain molecular characteristics of adlayer can be found elsewhere.27 In brief, (i) the evolution of dissipation change with the negative frequency shift upon protein deposition was almost negligible (Figures S52−53A,B); (ii) the normalized Δf n/n and ΔDn responses on all harmonics overlap well each other (Figures S52−53A,B); and (iii) more quantitatively, the ratio of ΔD/(−Δf/7) = 0.17 × 10−7 Hz−1 (for BSA, Figure S52C) and 0.7 × 10−7 Hz−1 (after an initial rigid adsorption phase, for lysozyme) ≪ 4 × 10−7 Hz−1 (Figure S53C), elucidating the rigid nature of protein adlayer. Therefore, the Sauerbrey relationship (eq 1) was used to quantify the amount of rigid adlayer (Δm), and all the calculated Δm are tabulated in Table 1.

redox-active PILs in electrochemical secondary energy storage devices is in progress. 3.4. Surface Immobilization of Polyphenol-Derived PILs and Subsequent Protein Adsorption/Inhibition Experiments by QCM-D. Protein adsorption plays a crucial role in a number of biomedical, industrial, and physiological processes.93,94 A variety of polymer brush-immobilized surfaces have been developed to either inhibit or enhance protein adsorption at solid−water interfaces.95,96Among various polymers, polyelectrolytes are widely employed to enhance protein adsorption at solid interfaces.97 However, limited by their poor adhesion toward surfaces, additional multistep and timeconsuming strategies (that are not always easy to implement at a large scale) are required to strongly bind polymers onto substrates.97 Herein, we demonstrate the multifunctionality of catechol/pyrogallol pendant units toward surface anchoring and synergistic effect of both the catechol/pyrogallol units and cationic polyelectrolyte P(VIm+Cl−) backbone toward proteins adsorption/inhibition at physiological pH. BSA and lysozyme were used as model proteins in this study. The QCM-D technique was employed to study real-time protein adsorption onto naked and polymer immobilized gold surfaces. Time-resolved changes in resonance frequency (Δf) and dissipation (ΔD) parameters were used to gain a qualitative idea about the nature of adsorption. Further ΔDn vs Δf n/n plots provided more insights into the mechanism of adsorption. The robust propensity of catechol or pyrogallol groups toward surface anchoring21−35 can be seen from the Δf QCM-D response in Figure 10. A stable baseline is attained during the

Δm = −C Δf

(1)

where C is the mass sensitivity constant (∼18.0 ng cm−2 at 4.95 MHz). Figure 10 shows the adsorption of BSA on gold surfaces modified by the different PVIm-based polymers. Once the excess of reversibly bound polymer is removed in the rinsing step, introduction of 1.0 mg mL−1 BSA solution in PBS buffer (pH 7.4) triggered a sharp negative f shift, and upon rinsing, the loss of adsorbed BSA on PVIm-cat/cato/pyr-Cl modified surfaces was negligible. Additionally, the obtained data were fitted into the Sauerbrey model to quantify the amount of adsorbed protein (Table 1). The polymer modified surfaces offer a favorable sorption capacity in the range of 1.6−3.8 g BSA (per gram of polymer), which corresponds to a 203−338% enhancement, compared to the naked surface, which can be ascribed to the BSA (negatively charged at pH 7.4)−cationic PVIm attractive electrostatic interactions,98 as can also be seen from Figure S54. A LBL deposition of three bilayers can be carried out by alternating deposition of oppositely charged [(PVIm-cat)+Cl−/(BSA)−]3 partners on QCM-D gold surface,

Figure 10. Change in frequency (Δf) upon the polymer immobilization and subsequent BSA adsorption on gold surfaces measured by QCM-D as a function of time. Δf responses for PVImcato-Cl (A), PVIm-pyr-Cl (B), PVIm-cat-Cl (C), and PVIm-et-Br (D) have been translated along the time axis for clarity purposes. The polymer/BSA concentration is 1.0 mg mL−1.

Table 1. Calculations of Δm (in ng cm−2) from QCM-D Data Using the Sauerbrey Relationship sample BSA Lys PVIm-cat-Cl PVIm-cato-Cl PVIm-pyr-Cl

BSA ads experiment

Lys ads experiment

Δmpola

Δmpola

ΔmLys

239 288 219

378 58 81 88

ΔmBSAa

a

ads capacity (g g−1) BSAb

Lysb

BSA ads enhancementc (%)

Lys antifoulingd (%)

2.9 3.8 3.5

0.24 0.28 0.4

203 338 250

85 79 77

371 259 328 267

754 1256 827

a

The hydrated uptake (mass) of the polymer/protein adlayer was calculated according to eq 1 from QCM-D experiments. bAmount of adsorbed protein (g) per unit weight (g) of the polymer immobilized on gold surface. cBSA ads enhancement (%) compared to the naked surface = ΔmBSA,polymer immobilized surface/ΔmBSA,naked surface. dLys antifouling (%) compared to the naked surface = [1− (ΔmLys,polymer immobilized surface/ ΔmLys,naked surface)]. L


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illustrating the robustness of the system to easily incorporate proteins in an adherent polymer film. In addition to the aforementioned attractive electrostatic interactions, a variable BSA adsorption on different polymer modified gold surfaces (Table 1) indicates that the chemical functionality of pendant groups plays a significant part through BSA−catechol/ pyrogallol interactions (hydrophobic and hydrogen-bonding interactions).99 To confirm the above-stated BSA−PVIm attractive electrostatic interactions, adsorption of another model protein, lysozyme (Lys), that is positively charged at pH 7.4 is considered. A representative alternating deposition of (PVImcat)+Cl− and (lysozyme)+ on gold surface (Figure S55) reveals only a very low lysozyme adsorption (0.24−0.4 g per gram of polymer, Table 1) in contrast to BSA (1.6−3.8 g g−1) due to the repulsive electrostatic interactions between similarly charged protein and polymer interface. Moreover, the PVImcat/cato/pyr-Cl tethered gold surface showed an improved resistance against the adsorption of Lys (77−85%, Table 1) compared to an unmodified surface. In summary, the same PVIm with catechol/pyrogallol pendant groups can be used to either inhibit or enhance protein adsorption at solid interface, without the need of prior surface treatments.

Article

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.macromol.6b01857. Experimental details of the synthesis of monomers and their intermediate compounds with their spectroscopic data (Figures S1−S24), DSC thermograms of monomers (Figure S25), GPC traces along with semilogarithmic plots and respective Mn plots (Figures S26−S35) as mentioned in the text, NMR, UV−vis, and ATR-FTIR spectra of polymers (Figures S36−S43) as mentioned in the text, solubility of PILs (Table S1), TGA (Figure S44), DSC (Figure S45), and CV (Figures S46−S51) plots of polymers and their analysis, QCM-D data plots (Figures S52−S55) as mentioned in the text (PDF)

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AUTHOR INFORMATION

Corresponding Authors

*Tel +3243663491; e-mail [email protected] (C.J.). *Tel +3243663465; e-mail [email protected] (C.D.). Notes

The authors declare no competing financial interest.

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4. CONCLUSIONS We have designed a novel family of redox-active poly(ionic liquid)s by organometallic-mediated radical polymerization of 1-vinyl-3-alkylimidazolium-type monomers bearing pendant catechol/pyrogallol in their protected version, and unprotected phenol, in DMF under very mild reaction conditions (0−2 °C). Structurally well-defined PIL-homopolymers and (multi)block copolymers of low dispersities were easily produced up to high monomer conversion (>90%) in short reaction time (2−3 h). Redox-active PILs bearing free catechol/pyrogallol units and featuring various counteranions were conveniently obtained by successive neat deprotection and facile counteranion exchange reactions in almost quantitative yields (>97%). Cyclic voltammetry studies of PVIm-cat/cato/pyr-TFSI in aqueous medium reveal characteristic catechol to o-quinone transformations; furthermore, a quasi-reversible two successive oneelectron doping/undoping of TBA+ and Li+ has been noted in the organic medium. These innovative redox-active PILs are therefore promising candidates as cathode materials for lithiumion battery and beyond, whose performances are under current investigation. Catechol/pyrogallol groups were then exploited to strongly anchor PILs to gold surface and to impart them specific properties. QCM-D studies validated that PILsmodified surfaces showed an enhancement (104−338%) or inhibition (77−85%) respectively toward BSA and lysozyme adsorption compared to the naked surface. As a result of the high binding capacities of catechol/pyrogallol groups to many substrates, no surface treatment was required to deposit adherent PILs bearing polyphenols. In general, this novel family of polymers can be foreseen as ideal candidates for the fabrication of “smart surfaces”, providing a ready access to universal surface anchoring, thereby imparting salient features of the PILs to the interface and even retaining the intrinsic properties of catechol/pyrogallol pendants. Examples illustrated in this paper convinced us that these multifunctional PILs will open up a vast array of applications not only in electrochemical energy storage devices but also for surface functionalization.

ACKNOWLEDGMENTS The authors thank the ITN Marie-Curie “Renaissance” funded by the People FP7 Programme, the “Fonds de la Recherche Scientifique” (FRS-FNRS), and the Belgian Science Policy in the frame of the Interuniversity Attraction Poles Program (P7/ 05)−Functional Supramolecular Systems (FS2) for financial support. A.D. and C.D. are Associate and Research Director by the F.R.S.-FNRS, respectively. C.D., C.J., and N.P. thank Prof. Olle Inganäs (Biomolecular and organic electronics, IFM, Linköping University, S-581 83, Linköping, Sweden) for discussions and for hosting N.P. in his research group for the evaluation of the redox activity of the polymers.

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REFERENCES

(1) Lu, J.; Yan, F.; Texter, J. Advanced Applications of Ionic Liquids in Polymer Science. Prog. Polym. Sci. 2009, 34 (5), 431−448. (2) Armand, M.; Endres, F.; MacFarlane, D. R.; Ohno, H.; Scrosati, B. Ionic-Liquid Materials for the Electrochemical Challenges of the Future. Nat. Mater. 2009, 8 (8), 621−629. (3) Kubisa, P. Ionic Liquids as Solvents for Polymerization processesProgress and Challenges. Prog. Polym. Sci. 2009, 34 (12), 1333−1347. (4) Green, O.; Grubjesic, S.; Lee, S.; Firestone, M. A. The Design of Polymeric Ionic Liquids for the Preparation of Functional Materials. Polym. Rev. 2009, 49 (4), 339−360. (5) Anderson, E. B.; Long, T. E. Imidazole- and ImidazoliumContaining Polymers for Biology and Material Science Applications. Polymer 2010, 51 (12), 2447−2454. (6) Mecerreyes, D. Polymeric Ionic Liquids: Broadening the Properties and Applications of Polyelectrolytes. Prog. Polym. Sci. 2011, 36 (12), 1629−1648. (7) Yuan, J.; Antonietti, M. Poly(ionic Liquid)s: Polymers Expanding Classical Property Profiles. Polymer 2011, 52 (7), 1469−1482. (8) Yuan, J.; Mecerreyes, D.; Antonietti, M. Poly(ionic Liquid)s: An Update. Prog. Polym. Sci. 2013, 38 (7), 1009−1036. (9) MacFarlane, D. R.; Tachikawa, N.; Forsyth, M.; Pringle, J. M.; Howlett, P. C.; Elliott, G. D.; Davis, J. H.; Watanabe, M.; Simon, P.; Angell, C. A. Energy Applications of Ionic Liquids. Energy Environ. Sci. 2014, 7 (1), 232−250. M


Article

Macromolecules

(30) Lee, B. P.; Messersmith, P. B.; Israelachvili, J. N.; Waite, J. H. Mussel-Inspired Adhesives and Coatings. Annu. Rev. Mater. Res. 2011, 41 (1), 99−132. (31) Lee, H.; Rho, J.; Messersmith, P. B. Facile Conjugation of Biomolecules onto Surfaces via Mussel Adhesive Protein Inspired Coatings. Adv. Mater. 2009, 21 (4), 431−434. (32) Faure, E.; Lecomte, P.; Lenoir, S.; Vreuls, C.; Van De Weerdt, C.; Archambeau, C.; Martial, J.; Jérô me, C.; Duwez, A.-S.; Detrembleur, C. Sustainable and Bio-Inspired Chemistry for Robust Antibacterial Activity of Stainless Steel. J. Mater. Chem. 2011, 21 (22), 7901. (33) Faure, E.; Falentin-Daudré, C.; Lanero, T. S.; Vreuls, C.; Zocchi, G.; Van De Weerdt, C.; Martial, J.; Jérôme, C.; Duwez, A.-S.; Detrembleur, C. Functional Nanogels as Platforms for Imparting Antibacterial, Antibiofilm, and Antiadhesion Activities to Stainless Steel. Adv. Funct. Mater. 2012, 22 (24), 5271−5282. (34) Yeroslavsky, G.; Girshevitz, O.; Foster-Frey, J.; Donovan, D. M.; Rahimipour, S. Antibacterial and Antibiofilm Surfaces through Polydopamine-Assisted Immobilization of Lysostaphin as an Antibacterial Enzyme. Langmuir 2015, 31 (3), 1064−1073. (35) Cheng, G.; Zheng, S.-Y. Construction of a High-Performance Magnetic Enzyme Nanosystem for Rapid Tryptic Digestion. Sci. Rep. 2014, 4, 6947. (36) He, H.; Luebke, D.; Nulwala, H.; Matyjaszewski, K. Synthesis of Poly(ionic Liquid)s by Atom Transfer Radical Polymerization with Ppm of Cu Catalyst. Macromolecules 2014, 47 (19), 6601−6609. (37) Vijayakrishna, K.; Jewrajka, S. K.; Ruiz, A.; Marcilla, R.; Pomposo, J. A.; Mecerreyes, D.; Taton, D.; Gnanou, Y. Synthesis by RAFT and Ionic Responsiveness of Double Hydrophilic Block Copolymers Based on Ionic Liquid Monomer Units. Macromolecules 2008, 41 (17), 6299−6308. (38) Chen, H.; Choi, J.-H.; Salas-de la Cruz, D.; Winey, K. I.; Elabd, Y. A. Polymerized Ionic Liquids: The Effect of Random Copolymer Composition on Ion Conduction. Macromolecules 2009, 42 (13), 4809−4816. (39) Mori, H.; Yahagi, M.; Endo, T. RAFT Polymerization of N -Vinylimidazolium Salts and Synthesis of Thermoresponsive Ionic Liquid Block Copolymers. Macromolecules 2009, 42 (21), 8082−8092. (40) Detrembleur, C.; Debuigne, A.; Hurtgen, M.; Jérôme, C.; Pinaud, J.; Fèvre, M.; Coupillaud, P.; Vignolle, J.; Taton, D. Synthesis of 1-Vinyl-3-Ethylimidazolium-Based Ionic Liquid (Co)polymers by Cobalt-Mediated Radical Polymerization. Macromolecules 2011, 44 (16), 6397−6404. (41) Coupillaud, P.; Fèvre, M.; Wirotius, A.-L.; Aissou, K.; Fleury, G.; Debuigne, A.; Detrembleur, C.; Mecerreyes, D.; Vignolle, J.; Taton, D. Precision Synthesis of Poly(Ionic Liquid)-Based Block Copolymers by Cobalt-Mediated Radical Polymerization and Preliminary Study of Their Self-Assembling Properties. Macromol. Rapid Commun. 2014, 35 (4), 422−430. (42) Cordella, D.; Kermagoret, A.; Debuigne, A.; Riva, R.; German, I.; Isik, M.; Jérôme, C.; Mecerreyes, D.; Taton, D.; Detrembleur, C. Direct Route to Well-Defined Poly(ionic Liquid)s by Controlled Radical Polymerization in Water. ACS Macro Lett. 2014, 3 (12), 1276−1280. (43) Cordella, D.; Kermagoret, A.; Debuigne, A.; Jérôme, C.; Mecerreyes, D.; Isik, M.; Taton, D.; Detrembleur, C. All Poly(ionic Liquid)-Based Block Copolymers by Sequential Controlled Radical Copolymerization of Vinylimidazolium Monomers. Macromolecules 2015, 48 (15), 5230−5243. (44) Weiss-Maurin, M.; Cordella, D.; Jérôme, C.; Taton, D.; Detrembleur, C. Direct One-Pot Synthesis of Poly(ionic Liquid) Nanogels by Cobalt-Mediated Radical Cross-Linking Copolymerization in Organic or Aqueous Media. Polym. Chem. 2016, 7 (14), 2521− 2530. (45) Cordella, D.; Debuigne, A.; Jérôme, C.; Kochovski, Z.; Taton, D.; Detrembleur, C. One-Pot Synthesis of Double Poly(Ionic Liquid) Block Copolymers by Cobalt-Mediated Radical PolymerizationInduced Self-Assembly (CMR-PISA) in Water. Macromol. Rapid Commun. 2016, 37, 1181.

(10) Kuzmicz, D.; Coupillaud, P.; Men, Y.; Vignolle, J.; Vendraminetto, G.; Ambrogi, M.; Taton, D.; Yuan, J. Functional Mesoporous Poly(ionic Liquid)-Based Copolymer Monoliths: From Synthesis to Catalysis and Microporous Carbon Production. Polymer 2014, 55 (16), 3423−3430. (11) Täuber, K.; Zhao, Q.; Antonietti, M.; Yuan, J. Tuning the Pore Size in Gradient Poly(ionic Liquid) Membranes by Small Organic Acids. ACS Macro Lett. 2015, 4 (1), 39−42. (12) Shaplov, A. S.; Marcilla, R.; Mecerreyes, D. Recent Advances in Innovative Polymer Electrolytes Based on Poly(ionic Liquid)s. Electrochim. Acta 2015, 175, 18−34. (13) Ho, T. D.; Zhang, C.; Hantao, L. W.; Anderson, J. L. Ionic Liquids in Analytical Chemistry: Fundamentals, Advances, and Perspectives. Anal. Chem. 2014, 86 (1), 262−285. (14) Suzuki, Y.; Nishide, H.; Tsuchida, E. Membranes of the Picket Fence Cobalt Porphyrin Complexed with Poly(vinylimidazole and -Pyridine)s: Selective Optical Response to Oxygen. Macromolecules 2000, 33 (7), 2530−2534. (15) Suzuki, M.; Kimura, M.; Shirai, H. Photo- and ThermoChromism of a ruthenium(II) Complex and Viologen-Containing Polymer Film. Chem. Commun. 1997, 2061−2062. (16) Coman, V.; Gustavsson, T.; Finkelsteinas, A.; von Wachenfeldt, C.; Hägerhäll, C.; Gorton, L. Electrical Wiring of Live, Metabolically Enhanced Bacillus Subtilis Cells with Flexible Osmium-Redox Polymers. J. Am. Chem. Soc. 2009, 131 (44), 16171−16176. (17) Feng, X.; Sui, X.; Hempenius, M. A.; Vancso, G. J. Electrografting of Stimuli-Responsive, Redox Active Organometallic Polymers to Gold from Ionic Liquids. J. Am. Chem. Soc. 2014, 136 (22), 7865−7868. (18) Gracia, R.; Vijayakrishna, K.; Mecerreyes, D. Poly(ionic Liquid)s with Redox Active Counter-Anions: All-in-One Reactants and Stabilizers for the Synthesis of Functional Colloids. React. Funct. Polym. 2014, 79 (1), 54−58. (19) Bui-Thi-Tuyet, V.; Trippé- Allard, G.; Ghilane, J.; Randriamahazaka, H. Surface and Electrochemical Properties of Polymer Brush-Based Redox Poly(Ionic Liquid). ACS Appl. Mater. Interfaces 2016, DOI: 10.1021/acsami.6b02107. (20) Suga, T.; Sakata, M.; Aoki, K.; Nishide, H. Synthesis of Pendant Radical- and Ion-Containing Block Copolymers via Ring-Opening Metathesis Polymerization for Organic Resistive Memory. ACS Macro Lett. 2014, 3 (8), 703−707. (21) Yang, J.; Cohen Stuart, M. A.; Kamperman, M. Jack of All Trades: Versatile Catechol Crosslinking Mechanisms. Chem. Soc. Rev. 2014, 43 (24), 8271−8298. (22) Ye, Q.; Zhou, F.; Liu, W. Bioinspired Catecholic Chemistry for Surface Modification. Chem. Soc. Rev. 2011, 40 (7), 4244. (23) Faure, E.; Falentin-Daudré, C.; Jérôme, C.; Lyskawa, J.; Fournier, D.; Woisel, P.; Detrembleur, C. Catechols as Versatile Platforms in Polymer Chemistry. Prog. Polym. Sci. 2013, 38 (1), 236− 270. (24) Moulay, S. Dopa/Catechol-Tethered Polymers: Bioadhesives and Biomimetic Adhesive Materials. Polym. Rev. 2014, 54 (3), 436− 513. (25) White, J. D.; Wilker, J. J. Underwater Bonding with Charged Polymer Mimics of Marine Mussel Adhesive Proteins. Macromolecules 2011, 44 (13), 5085−5088. (26) Isakova, A.; Topham, P. D.; Sutherland, A. J. Controlled RAFT Polymerization and Zinc Binding Performance of Catechol-Inspired Homopolymers. Macromolecules 2014, 47 (8), 2561−2568. (27) Patil, N.; Falentin-Daudré, C.; Jérôme, C.; Detrembleur, C. Mussel-Inspired Protein-Repelling Ambivalent Block Copolymers: Controlled Synthesis and Characterization. Polym. Chem. 2015, 6 (15), 2919−2933. (28) Lee, H.; Lee, B. P.; Messersmith, P. B. A Reversible Wet/dry Adhesive Inspired by Mussels and Geckos. Nature 2007, 448 (7151), 338−341. (29) Lee, H.; Dellatore, S. M.; Miller, W. M.; Messersmith, P. B. Mussel-Inspired Surface Chemistry for Multifunctional Coatings. Science (Washington, DC, U. S.) 2007, 318 (5849), 426−430. N


Article

Macromolecules (46) Debuigne, A.; Champouret, Y.; Jér ô m e, R.; Poli, R.; Detrembleur, C. Mechanistic Insights into the Cobalt-Mediated Radical Polymerization (CMRP) of Vinyl Acetate with cobalt(III) Adducts as Initiators. Chem. - Eur. J. 2008, 14 (13), 4046−4059. (47) He, H.; Zhong, M.; Adzima, B.; Luebke, D.; Nulwala, H.; Matyjaszewski, K. A Simple and Universal Gel Permeation Chromatography Technique for Precise Molecular Weight Characterization of Well-Defined Poly(ionic Liquid)s. J. Am. Chem. Soc. 2013, 135 (11), 4227−4230. (48) Weissman, S. A.; Zewge, D. Recent Advances in Ether Dealkylation. Tetrahedron 2005, 61 (33), 7833−7863. (49) Percec, V.; Sun, H. J.; Leowanawat, P.; Peterca, M.; Graf, R.; Spiess, H. W.; Zeng, X.; Ungar, G.; Heiney, P. A. Transformation from Kinetically into Thermodynamically Controlled Self-Organization of Complex Helical Columns with 3d Periodicity Assembled from Dendronized Perylene Bisimides. J. Am. Chem. Soc. 2013, 135 (10), 4129−4148. (50) Percec, V.; Peterca, M.; Sienkowska, M. J.; Ilies, M. A.; Aqad, E.; Smidrkal, J.; Heiney, P. A. Synthesis and Retrostructural Analysis of Libraries of AB3 and Constitutional Isomeric AB2 Phenylpropyl Ether-Based Supramolecular Dendrimers. J. Am. Chem. Soc. 2006, 128 (10), 3324−3334. (51) Percec, V.; Imam, M. R.; Peterca, M.; Wilson, D. A.; Heiney, P. A. Self-Assembly of Dendritic Crowns into Chiral Supramolecular Spheres. J. Am. Chem. Soc. 2009, 131 (3), 1294−1304. (52) Yuan, J.; Antonietti, M. Poly(ionic Liquid) Latexes Prepared by Dispersion Polymerization of Ionic Liquid Monomers. Macromolecules 2011, 44 (4), 744−750. (53) Paulini, R.; Lerner, C.; Diederich, F.; Jakob-Roetne, R.; Zürcher, G.; Borroni, E. Synthesis and Biological Evaluation of Potent Bisubstrate Inhibitors of the Enzyme Catechol O-Methyltransferase (COMT) Lacking a Nitro Group. Helv. Chim. Acta 2006, 89 (9), 1856−1887. (54) Grice, C. A.; Tays, K. L.; Savall, B. M.; Wei, J.; Butler, C. R.; Axe, F. U.; Bembenek, S. D.; Fourie, A. M.; Dunford, P. J.; Lundeen, K.; Coles, F.; Xue, X.; Riley, J. P.; Williams, K. N.; Karlsson, L.; Edwards, J. P. Identification of a Potent, Selective, and Orally Active Leukotriene A4 Hydrolase Inhibitor with Anti-Inflammatory Activity. J. Med. Chem. 2008, 51 (14), 4150−4169. (55) Bunck, D. N.; Sorenson, G. P.; Mahanthappa, M. K. CobaltMediated Radical Polymerization Routes to Poly(vinyl Ester) Block Copolymers. J. Polym. Sci., Part A: Polym. Chem. 2011, 49 (1), 242− 249. (56) Kermagoret, A.; Debuigne, A.; Jérôme, C.; Detrembleur, C. Precision Design of Ethylene- and Polar-Monomer-Based Copolymers by Organometallic-Mediated Radical Polymerization. Nat. Chem. 2014, 6 (3), 179−187. (57) Zhao, Y.; Yu, M.; Zhang, S.; Wu, Z.; Liu, Y.; Peng, C.-H.; Fu, X. A Well-Defined, Versatile Photoinitiator (salen)Co−CO 2 CH 3 for Visible Light-Initiated Living/controlled Radical Polymerization. Chem. Sci. 2015, 6 (5), 2979−2988. (58) Arteaga, J. F.; Ruiz-Montoya, M.; Palma, A.; Alonso-Garrido, G.; Pintado, S.; Rodríguez-Mellado, J. M. Comparison of the Simple Cyclic Voltammetry (CV) and DPPH Assays for the Determination of Antioxidant Capacity of Active Principles. Molecules 2012, 17 (12), 5126−5138. (59) Chevion, S.; Roberts, M. A.; Chevion, M. The Use of Cyclic Voltammetry for the Evaluation of Antioxidant Capacity. Free Radical Biol. Med. 2000, 28 (6), 860−870. (60) Crozier, A.; Jaganath, I. B.; Clifford, M. N. Dietary Phenolics: Chemistry, Bioavailability and Effects on Health. Nat. Prod. Rep. 2009, 26 (8), 1001−1043. (61) Kocaçalişkan, I.; Talan, I.; Terzi, I. Antimicrobial Activity of Catechol and Pyrogallol as Allelochemicals. Z. Naturforsch., C: J. Biosci. 2006, 61 (9−10), 639−642. (62) Taguri, T.; Tanaka, T.; Kouno, I. Antimicrobial Activity of 10 Different Plant Polyphenols against Bacteria Causing Food-Borne Disease. Biol. Pharm. Bull. 2004, 27 (12), 1965−1969.

(63) Liu, L.; Huang, Y.; Riduan, S. N.; Gao, S.; Yang, Y.; Fan, W.; Zhang, Y. Main-Chain Imidazolium Oligomer Material as a Selective Biomimetic Antimicrobial Agent. Biomaterials 2012, 33 (33), 8625− 8631. (64) Schrekker, H. S.; Donato, R. K.; Fuentefria, A. M.; Bergamo, V.; Oliveira, L. F.; Machado, M. M. Imidazolium Salts as Antifungal Agents: Activity against Emerging Yeast Pathogens, without Human Leukocyte Toxicity. MedChemComm 2013, 4 (11), 1457. (65) Chin, W.; Yang, C.; Ng, V. W. L.; Huang, Y.; Cheng, J.; Tong, Y. W.; Coady, D. J.; Fan, W.; Hedrick, J. L.; Yang, Y. Y. Biodegradable Broad-Spectrum Antimicrobial Polycarbonates: Investigating the Role of Chemical Structure on Activity and Selectivity. Macromolecules 2013, 46 (22), 8797−8807. (66) Zheng, Z.; Xu, Q.; Guo, J.; Qin, J.; Mao, H.; Wang, B.; Yan, F. Structure−Antibacterial Activity Relationships of Imidazolium-Type Ionic Liquid Monomers, Poly(ionic Liquids) and Poly(ionic Liquid) Membranes: Effect of Alkyl Chain Length and Cations. ACS Appl. Mater. Interfaces 2016, 8 (20), 12684−12692. (67) Wuts, P. G. M. Greene’s Protective Groups in Organic Synthesis; Wuts, P. G. M., Ed.; John Wiley & Sons, Inc.: Hoboken, NJ, 2014. (68) MacFarlane, D. R.; Forsyth, M.; Howlett, P. C.; Pringle, J. M.; Sun, J.; Annat, G.; Neil, W.; Izgorodina, E. I. Ionic Liquids in Electrochemical Devices and Processes: Managing Interfacial Electrochemistry. Acc. Chem. Res. 2007, 40 (11), 1165−1173. (69) Matos-Pérez, C. R.; White, J. D.; Wilker, J. J. Polymer Composition and Substrate Influences on the Adhesive Bonding of a Biomimetic, Cross-Linking Polymer. J. Am. Chem. Soc. 2012, 134 (22), 9498−9505. (70) Marcilla, R.; Blazquez, J. A.; Rodriguez, J.; Pomposo, J. A.; Mecerreyes, D. Tuning the Solubility of Polymerized Ionic Liquids by Simple Anion-Exchange Reactions. J. Polym. Sci., Part A: Polym. Chem. 2004, 42 (1), 208−212. (71) Marcilla, R.; Blazquez, J. A.; Fernandez, R.; Grande, H.; Pomposo, J. A.; Mecerreyes, D. Synthesis of Novel Polycations Using the Chemistry of Ionic Liquids. Macromol. Chem. Phys. 2005, 206 (2), 299−304. (72) Awad, W. H.; Gilman, J. W.; Nyden, M.; Harris, R. H.; Sutto, T. E.; Callahan, J.; Trulove, P. C.; DeLong, H. C.; Fox, D. M. Thermal Degradation Studies of Alkyl-Imidazolium Salts and Their Application in Nanocomposites. Thermochim. Acta 2004, 409 (1), 3−11. (73) Fredlake, C. P.; Crosthwaite, J. M.; Hert, D. G.; Aki, S. N. V. K.; Brennecke, J. F. Thermophysical Properties of Imidazolium-Based Ionic Liquids. J. Chem. Eng. Data 2004, 49 (4), 954−964. (74) Meyer, T. J.; Huynh, M. H. V.; Thorp, H. H. The Possible Role of Proton-Coupled Electron Transfer (PCET) in Water Oxidation by Photosystem II. Angew. Chem., Int. Ed. 2007, 46 (28), 5284−5304. (75) Marcus, R. A.; Sutin, N. Electron Transfers in Chemistry and Biology. Biochim. Biophys. Acta, Rev. Bioenerg. 1985, 811 (3), 265−322. (76) Häupler, B.; Wild, A.; Schubert, U. S. Carbonyls: Powerful Organic Materials for Secondary Batteries. Adv. Energy Mater. 2015, 5 (11), 1402034. (77) Liu, Y.; Ai, K.; Lu, L. Polydopamine and Its Derivative Materials: Synthesis and Promising Applications in Energy, Environmental, and Biomedical Fields. Chem. Rev. 2014, 114 (9), 5057−5115. (78) Dandawate, P. R.; Vyas, A. C.; Padhye, S. B.; Singh, M. W.; Baruah, J. B. Perspectives on Medicinal Properties of Benzoquinone Compounds. Mini-Rev. Med. Chem. 2010, 10 (5), 436−454. (79) Lin, Q.; Li, Q.; Batchelor-Mcauley, C.; Compton, R. G. TwoElectron, Two-Proton Oxidation of Catechol: Kinetics and Apparent Catalysis. J. Phys. Chem. C 2015, 119 (3), 1489−1495. (80) Costentin, C.; Robert, M.; Savéant, J.-M. Concerted ProtonElectron Transfers in the Oxidation of Phenols. Phys. Chem. Chem. Phys. 2010, 12 (37), 11179−11190. (81) Eggins, B. R.; Chambers, J. Q. Electrochemical Oxidation of Hydroquinone in Acetonitrile. J. Chem. Soc. D 1969, 58 (5), 232. (82) Ji, X.; Banks, C. E.; Silvester, D. S.; Wain, A. J.; Compton, R. G. Electrode Kinetic Studies of the Hydroquinone-Benzoquinone System and the Reaction between Hydroquinone and Ammonia in Propylene O


Article

Macromolecules Carbonate: Application to the Indirect Electroanalytical Sensing of Ammonia. J. Phys. Chem. C 2007, 111 (3), 1496−1504. (83) Guin, P. S.; Das, S.; Mandal, P. C. Electrochemical Reduction of Quinones in Different Media: A Review. Int. J. Electrochem. 2011, 2011 (3), 1−22. (84) Yamamoto, T.; Kimura, T.; Shiraishi, K. Preparation of πConjugated Polymers Composed of Hydroquinone, P -Benzoquinone, and P -Diacetoxyphenylene Units. Optical and Redox Properties of the Polymers. Macromolecules 1999, 32 (26), 8886−8896. (85) Wain, A. J.; Wildgoose, G. G.; Heald, C. G. R.; Jiang, L.; Jones, T. G. J.; Compton, R. G. Electrochemical ESR and Voltammetric Studies of Lithium Ion Pairing with Electrogenerated 9,10Anthraquinone Radical Anions Either Free in Acetonitrile Solution or Covalently Bound to Multiwalled Carbon Nanotubes. J. Phys. Chem. B 2005, 109 (9), 3971−3978. (86) Fujinaga, T.; Izutsu, K.; Nomura, T. Effect of Metal Ions on the Polarographic Reduction of Organic Compounds in Dipolar Arrotic Solvents. J. Electroanal. Chem. Interfacial Electrochem. 1971, 29 (1), 203−209. (87) Bruce, P. G.; Scrosati, B.; Tarascon, J.-M. Nanomaterials for Rechargeable Lithium Batteries. Angew. Chem., Int. Ed. 2008, 47 (16), 2930−2946. (88) Choi, N.-S.; Chen, Z.; Freunberger, S. A.; Ji, X.; Sun, Y.-K.; Amine, K.; Yushin, G.; Nazar, L. F.; Cho, J.; Bruce, P. G. Challenges Facing Lithium Batteries and Electrical Double-Layer Capacitors. Angew. Chem., Int. Ed. 2012, 51 (40), 9994−10024. (89) Kim, T. Y.; Lee, H. W.; Stoller, M.; Dreyer, D. R.; Bielawski, C. W.; Ruoff, R. S.; Suh, K. S. High-Performance Supercapacitors Based on Poly(ionic Liquid)-Modified Graphene Electrodes. ACS Nano 2011, 5 (1), 436−442. (90) Marcilla, R.; Curri, M. L.; Cozzoli, P. D.; Martínez, M. T.; Loinaz, I.; Grande, H.; Pomposo, J. A.; Mecerreyes, D. Nano-Objects on a Round Trip from Water to Organics in a Polymeric Ionic Liquid Vehicle. Small 2006, 2 (4), 507−512. (91) Kim, T.; Lee, H.; Kim, J.; Suh, K. S. Synthesis of Phase Transferable Graphene Sheets Using Ionic Liquid Polymers. ACS Nano 2010, 4 (3), 1612−1618. (92) Benoit, C.; Demeter, D.; Bélanger, D.; Cougnon, C. A RedoxActive Binder for Electrochemical Capacitor Electrodes. Angew. Chem., Int. Ed. 2016, 55 (17), 5318−5321. (93) Donlan, R. M. Biofilm Formation: A Clinically Relevant Microbiological Process. Clin. Infect. Dis. 2001, 33 (8), 1387−1392. (94) Harding, J. L.; Reynolds, M. M. Combating Medical Device Fouling. Trends Biotechnol. 2014, 32 (3), 140−146. (95) Banerjee, I.; Pangule, R. C.; Kane, R. S. Antifouling Coatings: Recent Developments in the Design of Surfaces That Prevent Fouling by Proteins, Bacteria, and Marine Organisms. Adv. Mater. 2011, 23 (6), 690−718. (96) Vladkova, T. G. Surface Engineered Polymeric Biomaterials with Improved Biocontact Properties. Int. J. Polym. Sci. 2010, 2010, 296094. (97) Yang, J.; Hua, Z.; Wang, T.; Wu, B.; Liu, G.; Zhang, G. Counterion-Specific Protein Adsorption on Polyelectrolyte Brushes. Langmuir 2015, 31 (22), 6078−6084. (98) Shu, Y.; Liu, M.; Chen, S.; Chen, X.; Wang, J. New Insight into Molecular Interactions of Imidazolium Ionic Liquids with Bovine Serum Albumin. J. Phys. Chem. B 2011, 115 (42), 12306−12314. (99) Wang, X.; Ho, C.-T.; Huang, Q. Investigation of Adsorption Behavior of (−)-Epigallocatechin Gallate on Bovine Serum Albumin Surface Using Quartz Crystal Microbalance with Dissipation Monitoring. J. Agric. Food Chem. 2007, 55 (13), 4987−4992.

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