Corruption Perceptions: the Trap of Democratization, a Panel Data Analysis

L’indice de perception de la corruption de Transparency International (TI) est le plus célèbre des indicateurs de corruption depuis sa première publication, en 1995. Cet indicateur est également considéré comme la plus robuste des mesures de ce fléau. Cependant, puisque il s’agit précisément d’un indicateur basé sur des perceptions, il connait certaines limites. Bien que Transparency International appelle inlassablement à une utilisation plus prudente de ses indicateurs, les décideurs continuent de lui prêter un rôle d’outil d’aide à la prise de décision. Nous avions isolé, dans un article précédent, le rôle joué par les médias dans les perceptions de la corruption. Nous avions suggéré que les jeunes démocraties puissent être pénalisées par l’indicateur phare de Transparency International. En effet, nous avions montré que l’ouverture des médias conduisait à une meilleure couverture des actes de corruption, entrainant avec elle une plus forte perception de la corruption déjà existante, mais non révélée. Notre article précédent utilisait des données en coupe transversale. Dans un souci d’amélioration de la robustesse et de la précision de l’analyse précédemment menée, nous avons collecté des séries temporelles afin d’entreprendre une analyse en données de panel. Dans ce nouvel article, nous analysons le lien entre démocratie et perceptions de la corruption à la lueur d’un possible biais d’ouverture des régimes en place, biais que nous avions qualifié de « réflectif ». The Corruption Perception Index (CPI) is the most famous corruption evaluation since its first publication by Transparency International (TI), in 1995. This index is also considered the most robust measure of corruption perceptions. However, since it precisely refers to perceptions, it inevitably faces some limitations. Although Transparency International continuously advocates for a better use of its indexes, policy makers keep using the CPI as a decision making tool. In a previous article we isolated the role played by the media in corruption perceptions. We previously suggested that young democracies were penalized by Transparency International. Indeed, we showed that media aperture leads to a better coverage of corruption deeds and therefore drives a stronger perception of already existing - but not yet broadcasted - corruption. Our previous paper was using cross-section data. Pursuing more consistent evidence and robustness improvement, we collected time series to perform a panel data analysis, questioning the stability and precision of our earlier findings. In this new paper, we investigate the link between democracy and corruption perceptions, in the light of a possible opening bias, we already called “reflective bias”. (Full text in french)

Preparation of Carboxylic Acid Functionalized Glycopolymers through RAFT and Post-Polymerization Modification for Biomedical Application

The primary theme of this dissertation involves the synthesis of well-defined primary amine functionalized polymers, subsequent modification of the polymers to produce novel carboxylic acid functionalized glycopolymers and surface polymerization of these systems utilizing controlled polymerization techniques. Additionally, the synthesis of new water-based allylic copolymer latexes is described. Carbohydrates are natural polymers which possess unlimited structural variations. They carry a huge density of information, and play major roles in recognition events and complex biological operations. For example, hyaluronic acid (HA), an anionic glycosaminoglycan, provides lubricating and cushioning properties in the extracellular matrix and has been found to be involved in the regulation of many cellular and biological processes. In industry, HA is used in a wide range of biomedical applications, including post surgical adhesion prevention, rheology modification in orthopedics, ophthalmic procedures, tissue engineering, hydrogels and implants. Limitations of current systems include cost, allergy induction and reduced performance capabilities in comparison to native HA. Therefore, it is of interest to prepare synthetic glycopolymer analogues to specifically target performance capabilities for biomedical applications. Reversible addition-fragmentation chain transfer polymerization (RAFT) is arguably the most versatile living radical polymerization technique in terms of the reaction conditions and monomer selection. Since the introduction of RAFT in 1998, researchers have employed the RAFT process to synthesize a wide range of water soluble (co)polymers with predetermined molecular weights, low polydispersities, and advanced architectures. However the RAFT polymerization of primary amine containing monomers such as 2-(aminoethyl metharylate) (AEMA) and ./V-(3-aminopropyl methacrylamide) (APMA) directly in water has yet to be reported. Since primary amine groups are amenable to a wide range of post-polymerization chemistries, primary amine functionalized polymers enable developments in the synthesis of controlled architecture glycopolymers. In addition, click chemistry can provide us an easy route to modify solid substrates with these polymers due to its simple reaction conditions and high reaction yield properties. The overall goal of this research is to prepare well-defined synthetic anionic glycosaminoglycan polymers by combining well-defined primary amine functionalized polymers with carboxylic acid functionalized sugars through a one-step reductive amination reaction. To achieve these goals, first, primary amine functionalized polymers were prepared through aqueous RAFT polymerization of AEMA and APMA. Second, Dglucuronic acid sodium salt was attached to reactive polymer precursors via reductive amination reactions in alkaline medium. Finally, the surface modification capabilities of primary amine functionalized polymers were investigated using click chemistry to create reactive surfaces allowing post-polymerization reactions. In this thesis, the first chapter concerns the first successful RAFT polymerization of unprotected AEMA directly in water and its successful block copolymerization with iV-2-hydroxypropylmethacrylamide (HPMA). The controlled living polymerization of AEMA was carried out directly in aqueous buffer using 4-cyanopentanoic acid dithiobenzoate (CTP) as the chain transfer agent (CTA), and 2,2\u27-Azobis(2- imidazolinylpropane) dihydrochloride (VA-044) as the initiator at 50 °C. The living character of the polymerization was verified with pseudo first order kinetic plots, a linear increase of the molecular weight with conversion, and low polydispersities (PDIs) (\u3c1.2). In addition, well-defined copolymers of poly(2aminoethyl methacrylate-6-./V-2- hydroxypropylmethacrylamide) (PAEMA-6-PHPMA) have been prepared through chain extension of poly(2-aminoethyl methacrylate) (PAEMA) macroCTA with HPMA in water. It is shown that the macroCTA can be extended in a controlled fashion resulting in near monodisperse block copolymers. The second chapter demonstrates the synthesis of novel carboxylic acid functionalized glycopolymers prepared via one step post-polymerization modification of poly(JV-[3-aminopropyl] methacrylamide) (PAPMA), a water soluble primary amine methacrylamide, in aqueous medium. PAPMA was first polymerized via aqueous RAFT polymerization using CTP as CTA, and 4,4\u27-Azobis(4-cyanovaleric acid) (V-501) as the initiator at 70 °C. The resulting well-defined PAPMA was then conjugated with Dglucuronic acid sodium salt through reductive amination in alkaline medium (pH 8.5) at 45 °C. The successful bioconjugation was proven through proton (^H) and carbon (13C) Nuclear Magnetic Resonance (NMR) spectroscopy and Matrix Assisted Laser Desorption Ionization Time of Flight (MALDI-TOF) mass spectroscopy analysis, which indicated near quantitative conversion. A similar bioconjugation reaction was conducted with PAEMA and PAEMA-6-PHPMA. For the PAEMA homo and block copolymers, however, poor conversion was obtained, most likely due to degradation reactions of PAEMA in alkaline medium. The third chapter details the direct preparation of a-alkynyl-functionalized PAEMA via RAFT polymerization. The controlled living polymerization of AEMA was carried out directly in dimethylsulfoxide (DMSO) using a-alkynyl functionalized CTP as CTA, and 2,2\u27-azobis(2,4-dimethyl-4-methoxyvaleronitrile) (V-70) as the initiator at 45 °C. The resulting polymers display low PDIs (\u3c1.2). In addition, the a-alkynylfuntionalized PAEMA was attached to an azide functionalized silicon wafer via click chemistry. Various characterization techniques including ellipsometry, contact angle measurements, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-IR), and atomic force microscopy (AFM) were used to characterize the polymer modified silicon wafers. It was shown that a non-uniform surface with a thickness of 11.1 nm was obtained. The last chapter (an additional chapter) details the copolymerization behavior of styrene with sec-butenyl acetate, whose copolymerization properties have not been reported. Copolymers were produced via semicontinuous emulsion polymerization and characterized via NMR, gel permeation chromatography, differential scanning calorimetry, dynamic light scattering, and atomic force microscopy. A high degree of chain termination due to allylic hydrogen abstraction was observed, as expected, with resultant decreases in molecular weight and in monomer conversion. How percentages of the ever, high conversions were achieved, and it was possible to incorporate high allylic acetate comonomer into the polymer chain. Copolymer thermal properties are reported

Cationic and reactive primary amine-stabilised nanoparticles via RAFT aqueous dispersion polymerisation

The synthesis of primary amine-functionalised diblock copolymer nanoparticles via polymerisation-induced self-assembly (PISA) using a RAFT aqueous dispersion polymerisation formulation is reported. The primary amine steric stabiliser is a macromolecular chain transfer agent (macro-CTA) based on 2-aminoethyl methacrylate AMA, which can be readily polymerised in its hydrochloride salt form with good control (Mw/Mn < 1.30) using RAFT aqueous solution polymerisation. Subsequent chain extension of this macro-CTA with 2-hydroxypropyl methacrylate (HPMA) leads to the formation of relatively monodisperse spherical nanoparticles (68 to 288 nm) at pH 6. However, worms or vesicles could not be obtained, because strong lateral repulsion between the highly cationic PAMA stabiliser chains impedes the formation of these higher order copolymer morphologies. Deprotonation of the primary amine stabiliser chains at or above pH 9 results in flocculation of these spherical nanoparticles as the PAMA block becomes uncharged. Diblock copolymer spheres, worms or vesicles can be synthesised that remain stable at pH 9 by supplementing the PAMA macro-CTA with a poly(glycerol monomethacrylate) (PGMA) macro-CTA, since this non-ionic block confers effective steric stabilisation in alkaline media. A series of diblock copolymer nanoparticles with the general formula ([1 − n]PGMAx + nPAMAy)–PHPMAz can be synthesised by optimising: (i) the mean degree of polymerisation (DP, or x) of the PGMA block, (ii) the PHPMA core-forming DP (or z); (iii) the mol fraction (n) of the PAMA stabiliser; and (iv) the copolymer concentration. These spheres, worms and vesicles are both cationic at low pH and colloidally stable at high pH. Furthermore, deprotonation of the protonated primary amine groups on the PAMA stabiliser chains at high pH renders these particles susceptible to epoxy-amine conjugation. This is demonstrated by the reaction between the primary amine groups on (0.8PGMA101 + 0.2PAMA96)–PHPMA1000 diblock copolymer spheres, and epoxide-functionalised diblock copolymer nanoparticles in aqueous solution at pH 8

Primary Amine-Functionalized Silicon Surfaces via Click Chemistry with α-Alkynyl-Functionalized Poly(2-aminoethyl methacrylate)

The direct preparation of α-alkynyl-functionalized poly(2-aminoethyl methacrylate) in its hydrochloride salt form (poly(AEMA)) via reversible addition-fragmentation chain transfer (RAFT) polymerization is reported. The controlled “living” polymerization of AEMA was conducted in DMSO at 45 °C using alkynyl-functionalized 4-cyanopentanoic acid dithiobenzoate (CTP) as the chain transfer agent (CTA), and 2,2′-azobis(2,4-dimethyl-4-methoxyvaleronitrile) (V-70) as the initiator. The resulting polymers display values of polydispersity index (PDI) lower than 1.2. Subsequently, the α-alkynyl-functionalized poly(AEMA) was attached to an azide-functionalized silicon wafer via click chemistry. Polymer-modified surfaces were evaluated using characterization techniques including ellipsometry, contact angle measurements, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and atomic force microscopy (AFM). A grafted polymer layer with average thickness of 15.2 nm and estimated grafting density of 0.39 chains/nm2 was obtained