Synthesis, Characterization, and Gas Permeation Properties

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General Introduction revealed that the biosynthesis of cellulose has been a part of the life cycle of cyanobacteria for over 3.5 billion years. 3 Recent years have witnessed an exciting development in the synthesis of naturally occurring polymers, namely in-vitro synthesis of cellulose, opening up new vistas on the horizon of macromolecular architecture. 4 Kobayashi and co-workers were the first to report the cellulase-catalyzed synthesis of cellulose starting from cellobiosyl fluoride 5 while Nakatsubo et al furnished the first example of chemosynthesis of cellulose employing the ring-opening polymerization of substituted D-glucose derivatives. 6 All the magnetism and beneficence of this fascinating biopolymer emanates from its specific structure, epitomizing an amazing conjunction of carbohydrate and polymer chemistry, drawing its roots from a low molecular weight carbohydrate, glucose, and emerging into the world of macromolecules with surprisingly specific and impressively diverse architectures, reactivity, and functions. The repeated connection of D-glucose building blocks, constituting the idiosyncratic cellulosic framework, bestows this homopolymer with unique structural peculiarities of extensive linearity, chain stiffness, chirality, hydrophilicity, and biodegradability, high degree of functionality, broad derivatization/modification capability, versatile fiber morphologies, and supramolecular architecture. Figure 1. Structure of Cellulose The molecular structure of cellulose is illustrated in Figure 1 delineating a carbohydrate polymer, comprised of β-D-glucopyranose units with acetal functions accomplishing the β-1,4-glucan linkage (between the equatorial hydroxy groups on C4 and C1 carbon atoms) with every second unit rotated 180° in the plane in order to O accommodate the acetal HO oxygen bridges in the preferred 1 O 4alignment, 2 as it is HO OH HO 1 O 3 HO 4 OH HO O HO OH 6 3 5 O HO 1 n O HO 4 OH HO O OH
General Introduction biogenetically formed. The presence of β-1,4-glycosidic linkage leads to an extensively linear polymeric structure with a large number of hydroxy groups (three per anhydroglucose (AGU) unit) present in the thermodynamically preferred 4 C1 conformation. The OH groups in cellulose are responsible for extensive hydrogen bonded networks imparting a variety of partially crystalline fiber structures and morphologies. The distinct polyfunctionality, high degree of chain stiffness, and sensitivity of the acetal linkages towards hydrolysis and oxidation are the most significant parameters in determining the role of cellulose in the world of synthesis and derivatization. Furthermore, the chemical reactivity and properties of cellulose are greatly influenced by the intermolecular interactions, chain lengths, chain-length distribution, and by the distribution of functional groups on the repeating units and along the polymer chains. Cellulose has been exploited as a chemical raw material for about 150 years. S Cell O C Cellulose Xanthogenate Scheme 2. Cellulose Esters of Commercial Significance SNa + NaOH, CS 2 HO Cell O NO2 Cellulose Nitrate OH 4 O HO Cell OH HNO 3, H 2SO 4, H 2O R R O Cell O C R O O O O R = CH 3 Cellulose Acetate n SO 3, NaOH R = CH 3 and CH 3 �CH 2 Cellulose Acetate Propionate R = CH 3 and CH 3 �CH 2 �CH 2 Cellulose Acetate Butyrate Cell O SO3Na Cellulose Sulphate +
Page 1 and 2: Synthesis, Characterization, and Ga
Page 3 and 4: Table of Contents General Introduct
Page 5: General Introduction cellulose deri
Page 9 and 10: General Introduction chemistry offe
Page 11 and 12: General Introduction solution-diffu
Page 13 and 14: General Introduction A simplified t
Page 15 and 16: General Introduction been observed
Page 17 and 18: polymers. 41,46 General Introductio
Page 19 and 20: General Introduction Keeping in vie
Page 21 and 22: General Introduction the derivatize
Page 23 and 24: General Introduction strategy (G1-a
Page 25 and 26: General Introduction In conclusion,
Page 27 and 28: General Introduction 5. (a) Kobayas
Page 29 and 30: General Introduction 15. (a) Goetma
Page 31 and 32: General Introduction American Chemi
Page 33 and 34: General Introduction Macromolecules
Page 35 and 36: Silylation of Ethyl Cellulose Intro
Page 37 and 38: Silylation of Ethyl Cellulose milli
Page 39 and 40: Silylation of Ethyl Cellulose chlor
Page 41 and 42: Silylation of Ethyl Cellulose Resul
Page 43 and 44: Silylation of Ethyl Cellulose Solub
Page 45 and 46: Silylation of Ethyl Cellulose 1.034
Page 47 and 48: Silylation of Ethyl Cellulose poly(
Page 49 and 50: Silylation of Ethyl Cellulose the r
Page 51 and 52: Silylation of Ethyl Cellulose D.; Y
Page 53 and 54: Chapter 2 51 Chapter 2 Synthesis, C
Page 55 and 56: 53 Chapter 2 are few and far betwee
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55 Chapter 2 constant volume/variab
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57 Chapter 2 Membrane Density. Memb
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59 Chapter 2 IR spectrum of 1 (Figu
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61 Chapter 2 1,3-bis(trifluoromethy
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63 Chapter 2 The increase in the po
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65 Chapter 2 other fluorinated poly
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67 Chapter 2 of the gas permeabilit
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69 Chapter 2 Gas Diffusivity and So
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71 Chapter 2 mobility of the perflu
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73 Chapter 2 1325-1329. (b) Hamza,
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Chapter 3 75 Chapter 3 Synthesis an
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77 Chapter 3 cost, and above all ap
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79 Chapter 3 molecular weights (Mn
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81 Chapter 3 1.99-2.07 (m, 2H, (CH3
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83 Chapter 3 25 °C, ppm): 11.9, 13
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85 Chapter 3 38.1, 44.7, 46.8, 47.9
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87 Chapter 3 CH2CH2C(=O)O), 2.50-4.
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89 Chapter 3 1091, 1053, 853, 806,
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91 Chapter 3 dendrons (G1-a-ІІ-G1
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93 Chapter 3 (DMAP) as a base, as s
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Figure 3. FTIR spectra of 1, 2c, an
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97 Chapter 3 (partly soluble) and 3
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99 Chapter 3 increased polarity of
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101 Chapter 3 that of 1, and approx
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103 Chapter 3 derivatization per th
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105 Chapter 3 (2a-c) were in the or
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107 Chapter 3 2709-2719. (b) Schenn
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109 Chapter 3 17. van Krevelen, D.
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Chapter 4 111 Chapter 4 Synthesis,
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113 Chapter 4 Since, no significant
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115 Chapter 4 Materials. Ethyl cell
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DStotal = DSEt + DSCarb (for 1a and
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119 Chapter 4 Figure 2. 1 H NMR spe
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121 Chapter 4 ruling out the possib
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123 Chapter 4 t-butyl moiety. A str
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125 Chapter 4 reported to lead to t
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127 Chapter 4 Table 4. Gas Permeabi
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129 Chapter 4 augmentation in eithe
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131 Chapter 4 indicate the signific
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133 Chapter 4 M.-R. J. Appl. Polym.
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Chapter 5 135 Chapter5 Synthesis an
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137 Chapter5 acid- and peptide-cont
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139 Chapter5 Specific rotations ([
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141 Chapter5 1.66 (brs, 1.1H, NHCH(
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143 Chapter5 as shown in Scheme 1,
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145 Chapter5 in Table 1. The molecu
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147 Chapter5 almost same pattern of
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Conclusions Table 3. Thermal Proper
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151 Chapter5 W.; Jing, X. J. Polym.
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Chapter 5 Synthesis and Properties
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Acknowledgments While submitting th
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Synthesis, Characterization, and Ga
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