Synthesis, Characterization, and Gas Permeation Properties

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92 Dendronization of Ethyl Cellulose All of the synthetic procedures were carried out several times and can be considered optimized. The characterization of the first and second generation amide-containing dendrons was accomplished by 1 H and 13 C NMR spectroscopy, mass spectrometry, and elemental analysis. Synthesis of Dendronized Ethyl Cellulose. The incorporation of dendritic moieties (G1-a- ІІ–G1-c-ІІ and G2-a-ІІ–G2-c-ІІ) into ethyl cellulose (1) was carried out by coupling the carboxyl termini of dendrons to the hydroxy functionalities of ethyl cellulose; N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC·HCl) was employed as a condensating agent and 4-(dimethylamino)pyridine Scheme 2. Esterification of ethyl cellulose with G1 and G2 dendrons. a a Abbreviations: EDC·HCl, N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide Hydrochloride; DMAP, 4-(Dimethylamino)pyridine.
93 Chapter 3 (DMAP) as a base, as shown in Scheme 2, and the results are summarized in Table 1. The dendronized ethyl cellulose derivatives (2a–c and 3a–c) were characterized by the 1 H NMR and IR spectroscopy and elemental analysis. The DSEt of 1 was estimated to be 2.69, by calculating the integration ratio of methyl protons to the rest of the protons in 1, indicating the presence of 0.31 hydroxy groups per anhydroglucose unit. 21 The 1 H NMR spectra of one of the G1 dendrons (G1-c-ІІ), ethyl cellulose (1), and the corresponding dendronized ethyl cellulose (2c) are shown in Figure 1 and a similar information for a G2-derivatized ethyl cellulose (3c) is depicted in Figure 2. Although the 1 H NMR spectra of the dendronized polymers provide a clear indication of the substitution of hydroxy protons by the dendritic moieties, the calculation of the exact degree of esterification could not be carried out due to the overlapping of the peaks arising from the methyl protons of the ethyl group of ethyl cellulose and those of the dendrons’ periphery. Further evidence was furnished by the presence of the peaks characteristic of the carbonyl group of an ester (1746–1732 cm -1 ) in the IR spectra of the dendronized derivatives (2a–c and 3a–c). The IR spectrum of 1 (Figure 3) has a broad band due to the residual hydroxy groups (3600–3200 cm -1 ), which did not disappear completely upon dendronization as the NH groups of the dendritic moiety also absorb IR radiation in the same wavenumber region. Despite the fact that the starting as well as the dendronized polymers are soluble in chloroform, the attempts to carry out molecular weight determination by GPC, using chloroform as an eluent, were unsuccessful to yield satisfactory and reproducible results probably due to the aggregation of the polymers. Therefore, molecular weights of the polymers were determined by making use of the LiBr solution in DMF (10 mM) and reproducible results were obtained for G1-derivatized ethyl cellulose (2a–c). According to GPC data of the polymers (Table 1), the number-average molecular weight (Mn) of 1 was found to be 71 000 and a significant increase in the Mn values (≥ 222 000) was observed as a consequence of the substitution of small hydroxy groups with fairly bulky G1 dendritic moieties. Meanwhile, the polydispersity indices (Mw/Mn) of the dendronized polymers (2a–c)
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Synthesis, Characterization, and Ga
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Table of Contents General Introduct
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General Introduction cellulose deri
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General Introduction biogenetically
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General Introduction chemistry offe
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General Introduction solution-diffu
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General Introduction A simplified t
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General Introduction been observed
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polymers. 41,46 General Introductio
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General Introduction Keeping in vie
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General Introduction the derivatize
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General Introduction strategy (G1-a
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General Introduction In conclusion,
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General Introduction 5. (a) Kobayas
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General Introduction 15. (a) Goetma
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General Introduction American Chemi
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General Introduction Macromolecules
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Silylation of Ethyl Cellulose Intro
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Silylation of Ethyl Cellulose milli
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Silylation of Ethyl Cellulose chlor
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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
Page 57 and 58: 55 Chapter 2 constant volume/variab
Page 59 and 60: 57 Chapter 2 Membrane Density. Memb
Page 61 and 62: 59 Chapter 2 IR spectrum of 1 (Figu
Page 63 and 64: 61 Chapter 2 1,3-bis(trifluoromethy
Page 65 and 66: 63 Chapter 2 The increase in the po
Page 67 and 68: 65 Chapter 2 other fluorinated poly
Page 69 and 70: 67 Chapter 2 of the gas permeabilit
Page 71 and 72: 69 Chapter 2 Gas Diffusivity and So
Page 73 and 74: 71 Chapter 2 mobility of the perflu
Page 75 and 76: 73 Chapter 2 1325-1329. (b) Hamza,
Page 77 and 78: Chapter 3 75 Chapter 3 Synthesis an
Page 79 and 80: 77 Chapter 3 cost, and above all ap
Page 81 and 82: 79 Chapter 3 molecular weights (Mn
Page 83 and 84: 81 Chapter 3 1.99-2.07 (m, 2H, (CH3
Page 85 and 86: 83 Chapter 3 25 °C, ppm): 11.9, 13
Page 87 and 88: 85 Chapter 3 38.1, 44.7, 46.8, 47.9
Page 89 and 90: 87 Chapter 3 CH2CH2C(=O)O), 2.50-4.
Page 91 and 92: 89 Chapter 3 1091, 1053, 853, 806,
Page 93: 91 Chapter 3 dendrons (G1-a-ІІ-G1
Page 97 and 98: Figure 3. FTIR spectra of 1, 2c, an
Page 99 and 100: 97 Chapter 3 (partly soluble) and 3
Page 101 and 102: 99 Chapter 3 increased polarity of
Page 103 and 104: 101 Chapter 3 that of 1, and approx
Page 105 and 106: 103 Chapter 3 derivatization per th
Page 107 and 108: 105 Chapter 3 (2a-c) were in the or
Page 109 and 110: 107 Chapter 3 2709-2719. (b) Schenn
Page 111 and 112: 109 Chapter 3 17. van Krevelen, D.
Page 113 and 114: Chapter 4 111 Chapter 4 Synthesis,
Page 115 and 116: 113 Chapter 4 Since, no significant
Page 117 and 118: 115 Chapter 4 Materials. Ethyl cell
Page 119 and 120: DStotal = DSEt + DSCarb (for 1a and
Page 121 and 122: 119 Chapter 4 Figure 2. 1 H NMR spe
Page 123 and 124: 121 Chapter 4 ruling out the possib
Page 125 and 126: 123 Chapter 4 t-butyl moiety. A str
Page 127 and 128: 125 Chapter 4 reported to lead to t
Page 129 and 130: 127 Chapter 4 Table 4. Gas Permeabi
Page 131 and 132: 129 Chapter 4 augmentation in eithe
Page 133 and 134: 131 Chapter 4 indicate the signific
Page 135 and 136: 133 Chapter 4 M.-R. J. Appl. Polym.
Page 137 and 138: Chapter 5 135 Chapter5 Synthesis an
Page 139 and 140: 137 Chapter5 acid- and peptide-cont
Page 141 and 142: 139 Chapter5 Specific rotations ([
Page 143 and 144: 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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