Biosynthesis of Au-Pd/MgO catalysts and solvent free selective liquid phase oxidation of benzyl alcohol

受到近年来日益增长的“绿色化学”概念的驱动，利用生物还原法来制备纳米颗粒，得到了研究者们的青睐，其将是一种替代传统化学法和物理法的有效方法。另一方面，金钯双金属纳米颗粒相比于单金属纳米颗粒而言，在磁学、光学、电子、催化应用方面拥有许多新特性。因此，本论文采用以侧柏叶提取液为代表的植物还原法制备负载型金钯双金属催化剂，并将其应用于基于分子氧和无溶剂法的苯甲醇液相氧化反应。采用分子氧为氧化剂的苯甲醇液相氧化法，将苯甲醇选择氧化为苯甲醛是一条绿色环保工艺。该方法工艺简单、环境友好，有望高收率制得苯甲醛，在日益严格的环保要求和不断增长的“无氯”苯甲醛市场需求量的环境下，研制高效的金钯双金属催化剂催化苯...Supported bimetallic gold-palladium (Au-Pd) catalysts synthesized with plant biomass has been an elevated and consistent research area because of their pure green nature, cost effectiveness, and less energy consuming process of synthesis which is a superior advantage over chemically and physically synthesized catalysts. Different from their monometallic counterparts in electronic, optical and magn...学位：工学硕士院系专业：化学化工学院化学工程与生物工程系_化学工程学号：2042010115442

Syntheses of Novel Biodegradable Materials from Biorenewable Resources through Nitroxide Mediated Polymerization; Green, Sustainable and Environmentally Benign Materials.

We have depended on petroleum or fossil sources for raw materials to synthesize polymers in order to meet the high demand of polymeric materials for over a century. Notwithstanding, polymers derived from these sources (synthetic polymers) are toxic to the environment. They are also expensive and are scarce sometimes because their raw material sources are nonrenewable. Biodegradable polymers (BDP) derived from biorenewable resources on the other hand are ecofriendly, cost-effective and sustainable. The raw materials which are mainly from agricultural and forestry products and the shells of crustaceans are readily available, cheap and renewable. The final polymers derived from these raw materials are potential replacement to synthetic polymers. As appealing as biodegradable polymers derived from biorenewable resources might be, there a number of challenges surrounding their synthesis and their properties sometimes do not meet the demands of certain applications. Some applications require very strong mechanical properties which may not be in possession of some biodegradable polymers derived from biorenewable resources. Copolymerization of these polymers with synthetic ones produces novel versatile polymeric materials which are biodegradable and possess robust mechanical properties suitable for different applications. Nitroxide mediated polymerization (NMP) is one of the most effective and efficient free radical living polymerization technique employed in chemical grafting of polymers. NMP as well as other free radical polymerization techniques can be used in tuning polymers into macromolecular architectures of different shapes, sizes and structures as opposed to conventional condensation polymerization. The advantage of NMP is that, it is a facile metal free process and therefore greener than other free radical techniques. This process is also viable for employment in the commercial production of polymers. In this light, the exploitation of the NMP technique for the production of biodegradable polymers from biorenewabe resources is essential and further research is required. The first chapter discusses elaborately the objectives of replacing synthetic polymers from petroleum sources with biodegradable ones from biorenewable resources, underlining the main reasons for this work. It further states the development in the research and production of biodegradable polymers from biorenewable resources. xiii In the second chapter, the art of NMP and its role in the synthesis and development of biodegradable polymers from renewable resources was discussed. It also entails a brief discussion on nitroxides and alkoxyamines which are the most important species involved in the NMP process. Chapter three constitutes the experimental synthesis of nitroxides, macro(alkoxyamines), monomers from biorenewable resources and graft copolymers. 2-phenyl-3-(phenylimino)-3Hindole 1-oxide (DPAIO) and its alkoxyamine were synthesized. N-tert-butyl-N-(1-diethyl phosphono-2,2-dimethylpropyl) nitroxide (SG1) nitroxide and its alkoxyamine, commercial BlocBuilder MA were mostly employed in the NMP process to produce the copolymers. The monomers derived from biorenewable resources included corn starch, cellulose, chitosan, castor oil, maleic acid, acrylamide and amino acids. Polystyrene (PS) and methyl methacrylate (MMA) are some synthetic polymers which were grafted onto the polymers from biorenewable resources. The copolymers in this chapter where synthesized through atom transfer radical addition (ATRA) and NMP. The products synthesized in chapter three were characterized and the results discussed in chapter four. The characterization techniques used were near magnetic resonance (NMR), Fourier Transform Infra-red (FTIR), differential scanning calorimetry (DSC) and electron paramagnetic resonance (EPR). FTIR analyses confirmed the formation of several copolymers were formed but only cellulose acetate-g-poly (methyl methacrylate) (CA-g-PMMA) was further confirmed by NMR and DSC. Chapter five is a summary of chapter one to four. It provides an elaborate argument on the replacement of synthetic polymers with biodegradable polymers from biorenewable resources. Chapter six discusses a specific project carried out at Aix-Marseille Université, centre de la recherche scientifique (CNRS), institute chimie radicalaire (ICR). The aim of this project was to develop hydrogels for the treatment and recovery of ischemic stroke. A novel blockgraft amphiphilic copolymer, polylactide-block-poly(N-isopropylamide-co-polyethylene glycol methacrylate) (PLA-b-P(NIPAAm-co-PEGMA)) was synthesized. 15wt% of the hydrogel formed by the polymer in phosphate buffer saline solution undergoes a sol-gel transition between 25°C and 37°C through micelle packing/rearrangement upon heating. The xiv synthesis of this biomaterial was based on the strategies of ring opening polymerization (ROP), intermolecular radical addition (IRA) and nitroxide mediated polymerization (NMP). Characterization of the copolymers was done by size exclusion chromatography (SEC), dynamic light scattering (DLS) and NMR. 15wt% of the hydrogel degrades after 48 h at 37°C by hydrolysis. The biomaterial also showed good mechanical properties since it did not shrink or break after heating at 50°C. Key words: Biodegradable; Polymer; Nitroxide Mediated Polymerization, Biorenewable resources, cellulose, polylactide, poly( N-isopropylamide), SG1, BlocBuilder MA, hydrogel

Cellulose Acetate-Graft-Poly (Methyl Methacrylate): A “Graft from” Approach of Nitroxide Mediated Radical Polymerization

Poly (methyl methacrylate) was grafted onto cellulose acetate backbone using a “graft from” of Nitroxide Mediated Radical Polymerization (NMRP). The formation of cellulose acetate-co-poly (methyl methacrylate) using N-tert-butyl- N- (1-diethylphosphono-2,2-dimethylpropyl) (SG1)-nitroxide based macroalkoxyamine system was confirmed by FTIR and NMR analyses. The copolymer exhibited living characteristics as shown by NMR. DSC investigations showed a copolymer with a rich poly (methyl methacrylate) phase around 120°C and a rich cellulose acetate phase at around 175°C

A Sacrificial PLA Block Mediated Route to Injectable and Degradable PNIPAAm-Based Hydrogels

Thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm)-based injectable hydrogels represent highly attractive materials in tissue engineering and drug/vaccine delivery but face the problem of long-term bioaccumulation due to non-degradability. In this context, we developed an amphiphilic poly(D,L-lactide)-b-poly(NIPAAm-co-polyethylene glycol methacrylate) (PLA-b- P(NIPAAm-co-PEGMA)) copolymer architecture, through a combination of ring-opening and nitroxide-mediated polymerizations, undergoing gelation in aqueous solution near 30 °C. Complete hydrogel mass loss was observed under physiological conditions after few days upon PLA hydrolysis. This was due to the inability of the resulting P(NIPAAm-co-PEGMA) segment, that contains sufficiently high PEG content, to gel. The copolymer was shown to be non-toxic on dendritic cells. These results thus provide a new way to engineer safe PNIPAAm-based injectable hydrogels with PNIPAAm-reduced content and a degradable feature

Bimetallic Au-Pd/MgO as efficient catalysts for aerobic oxidation of benzyl alcohol: A green bio-reducing preparation method

The oxidation of benzyl alcohol, with molecular oxygen at atmospheric pressure in an aqueous medium, is investigated using Au-Pd/MgO bimetallic catalysts to examine the effect of catalyst parameters (viz. preparation method. Au/Pd molar ratio, and calcinations temperature) and reaction conditions (viz. reaction temperature and oxygen flow rate) on conversion and selectivity. The bimetallic catalysts were prepared via two novel reduction methods with bio-reducing agents and were characterized by transmission electron microscopy, X-ray diffraction, diffuse reflectance UV-vis spectroscopy, and thermogravimetric analysis to understand synergistic interactions between Au and Pd. Under optimal conditions, the Au-Pd bimetallic catalysts, with a 1:1 molar ratio and 9.7 +/- 1.3 nm particle size, exhibited remarkably enhanced catalytic activity (>52%) and selectivity (similar to 100%) compared with their monometallic counterparts. Moreover, the activity of the catalysts was maintained after six recycles without agglomeration. (C) 2012 Elsevier B.V. All rights reserved.NSFC [21106117, 21036004, 20976146]; NSF-Fujian Projects [2010J05032