Catalytic Synthesis and Characterization of Biodegradable ...

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Chapter 1 1.4.4 Polyhydroxybutyrate Polyhydroxybutyrate (PHB) is a biodegradable thermoplastic polymer produced by micro-organisms. 94 The polymer is primarily a product of carbon assimilation and is employed by micro-organisms as a form of energy storage molecule to be metabolized when other common energy sources are not available. The poly(3-hydroxybutyrate) (P3HB) (Figure 1.4.4) form of PHB is probably the most common type of polyhydroxyalkanoate. PHB has a melting point of 175 and glass transition temperature of 15 . The tensile strength is 40 MPa, which is close to that of polypropylene. 95 PHB is water insoluble and relatively resistant to hydrolytic degradation, which differentiates PHB from most other currently available biodegradable plastics, such as PLA, PCL, and PGA, which are either water soluble or moisture sensitive. However ICI had developed the material to pilot plant stage in the 1980s, but interest faded when it became clear that the cost of material was too high. 1.5 Electroactive Polymers Figure 1.4.4 Chemical structure of poly(3-hydroxybutyrate). Recent advances in electroactive polymers have aroused more and more interests in their application as biomedical materials. These researches based on the theory that a multitude of cell functions, such as attachment, proliferation, migration, and differentiation could be modulated through electrical stimulation 96 , which have been demonstrated for a long time. Presently the electroactive polymers used are all conducting polymers, which have electrical and optical properties similar to inorganic semiconductors or metals. 97 Moreover, they also exhibit the unique properties as conventional polymers, including ease of synthesis and processing. These attractive properties have given these polymers a wide range of applications in the biological field, such as the matrix for tissue engineering or drug carrier for controlled release. 98, 99 Although there have been many conducting polymers discovered and characterized at the past 30 years, a small number of them have been developed for the ‐ 18 ‐
- 19 - Polymerization and Applications of Biodegradable Polyesters biomedical applications, including poly(pyrrole)s, polyanilines and polythiophenes. Thus, developing new type of electroactive polymers for biomedical application is still necessary both in theory and in practice. 1.5.1 Introduction of Electroactive Polymers 1.5.1.1 Poly(acetylene) Poly(acetylene) is the simplest conjugated polymer and historically the discovery of the metallike conductivity of poly(acetylene) doping triggered the explosion of the research to electroactive polymers (Figure 1.5.1A). Poly(acetylene) can exist in two isomeric forms: cis-transoid and trans-transoid, commonly called cis- and trans-poly(acetylene), respectively. The latter form being thermodynamically stable since cis to trans isomerization is irreversible. Polyacetylene is one of the most promising materials for applications in optoelectronics. 100 The conductivity of this polymer after doping is equal to that of copper, and some forms of polyacetylene have record values of non-linear third-order optical susceptibility. Because it contains high concentrations of unsaturated sites which can be easily attacked by ozone and UV light, polyacetylene is very unstable to the environment. 101 The low stability of polyacetylene has been the major obstacle in the way of practical applications of this polymer. An effective approach to obtain stable poly(acetylene) without weakening its conductivity was blend poly(acetylene) with processable plastics. Figure 1.5.1 Structure of poly(acetylene) (A), polypyrrole (B) and poly(thiophene) (C).
Page 1 and 2: Catalytic Synthesis and Characteriz
Page 3 and 4: Preface Biodegradable polyesters ha
Page 5 and 6: Chapter 3 Polymerization of Lactic
Page 7 and 8: Chapter 1 Polymerization and Applic
Page 9 and 10: - 3 - Polymerization and Applicatio
Page 13 and 14: 1.2.2 Aluminum Catalysts - 7 - Poly
Page 17 and 18: 1.3 Polylactide 1.3.1 Introduction
Page 19 and 20: - 13 - Polymerization and Applicati
Page 21 and 22: 1.3.4 Application of PLA Figure 1.3
Page 23: - 17 - Polymerization and Applicati
Page 27 and 28: 1.5.1.4 Polyaniline (PANi) - 21 - P
Page 47 and 48: 1.6.1 Radical Polymers for Organic
Page 51 and 52: initialization of the device by app
Page 55 and 56: 1.6.2.4 Others - 49 - Polymerizatio
Page 63 and 64: 182. R. B. Weller, J. Invest. Derma
Page 65 and 66: Chapter 2 Synthesis and Electrochem
Page 67 and 68: Synthesis and Electrochemistry of S
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Synthesis and Electrochemistry of S
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Chapter 3 3.1 Introduction Poly(lac
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Chapter 3 polydispersity index (PDI
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Chapter 3 aluminum based complexes
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Chapter 3 3.5 Conclusions Co(III) c
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Chapter 3 22. Z. H. Tang, X. S. Che
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Chapter 4 4.1 Introduction Stimulus
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Chapter 4 the proton of methenyl gr
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Chapter 4 attributed to the amide g
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Chapter 4 4.4 Thermal Properties Th
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Chapter 4 Figure 4.8 MTT assay for
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Chapter 4 The 1 H NMR and 13 C NMR
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Chapter 4 Cell viability (%) = (Asa
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Chapter 5 Synthesis of Triblock Cop
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5.2 Synthesis of Triblock Copolymer
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Sample Table 1. Feed and result com
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= 25 μm. B: MTT assay for the cyto
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‐ 109 ‐ Synthesis of Triblock C
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‐ 111 ‐ Synthesis of Triblock C
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Chapter 6 6.1 Introduction Since th
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Chapter 6 6.3 Synthesis of MPEG-b-P
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Chapter 6 used to characterize the
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Chapter 6 Figure 6.6 Cyclic voltamm
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Chapter 6 vivo cytotoxicity was als
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Chapter 6 NMR. Characterization of
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Chapter 6 CO2 for 24 h. RSC96 cells
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Chapter 7 Conclusion and Future Pro
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‐ 131 ‐ Conclusion and Future P
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‐ 133 ‐ Conclusion and Future P
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13. Xuan Pang, Xuesi Chen, Xiuli Zh
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Acknowledgments The present thesis
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