Synthesis, Characterization, and Gas Permeation Properties

More documents

Recommendations

Info

Chapter 1 31 Chapter 1 Synthesis, Characterization, and Gas Permeation Properties of Silylated Derivatives of Ethyl Cellulose Abstract Silyl ethers of ethyl cellulose (2a–f) were synthesized in good yield by the reaction of various chlorosilanes with residual hydroxy groups of ethyl cellulose (1; DSEt, 2.69). 1 H NMR and FTIR spectra of the silylated polymers furnished the evidence for complete substitution of hydroxy protons by the silyl groups. Silylated derivatives of ethyl cellulose (2a–f) were soluble in common organic solvents and displayed enhanced solubility in relatively nonpolar solvents due to the substitution of hydroxy groups. The onset temperatures of weight loss of the silylated derivatives (2a–f) in air were higher than 270 ºC, indicating fair thermal stability. Free-standing membranes of 1 and 2a–f were fabricated by casting their toluene solution and all the silylated derivatives (2a–f) exhibited enhanced gas permeability (P) as compared to ethyl cellulose (1). An increment in the size of the silyl group led to the decrement in gas permeability of the polymers, and trimethylsilyl derivative (2a) exhibited the highest P value. The PCO2/PN2 values of the polymers (2a–f) were observed to be in the range of 15–19, and the data for 2a, 2b, and 2c were located above the upper bound in the plot of permselectivity versus permeability for CO2/N2 gas pair. For all the six gases under study, gas diffusion coefficients (D) increased upon silylation while gas solubility coefficients (S) underwent a decline.
Silylation of Ethyl Cellulose Introduction Polymeric gas separation membranes have engrossed substantial prominence, contributing to sustainable chemical processing in the past two decades and are being exploited in a wide array of commercial applications. 1 At present, a variety of gas mixtures of industrial interest are being separated by the selective permeation of the components through non-porous membranes made of glassy polymers such as polyacetylenes, polyimides, and polysulfones. 2 Among them silylated polyacetylenes are a class of highly gas-permeable glassy materials as they possess many microvoids in the polymer matrix due to their stiff main chain composed of alternating double bonds and the steric effect of the spherical pendant groups. 1b,3 One of them, poly(1-trimethylsilyl-1-propyne) [poly(TMSP)] is the most gas-permeable material and many studies concerning the gas permeation properties of this polymer have been reported till today. 1b,4 Most of poly(1-aryl-2-phenylacetylenes) having spherical substituents on the phenyl moiety also exhibit high gas permeability. 3a,5 For instance, the oxygen permeability coefficient (PO2) of poly[1-phenyl-2-(p-trimethylsilyl)phenylacetylene] [poly(TMSDPA)] is 1500 barrers, 5a which is quite high among all the synthetic polymers. However, there remains a strong need to develop high flux membranes with high selectivity and fouling-resistant properties for large-scale applications. Physical or chemical modification of polymers is an attractive alternative to tailor the gas permeability and permselectivity of membrane-forming materials, as desired for specific applications. Ethyl cellulose is derived from an inexhaustible natural polymeric material, cellulose, and possesses the fascinating structure and properties such as extensive linearity, chain stiffness, good solubility in organic solvents, adequate membrane-forming ability, moderate gas permeation/pervaporation capability, excellent durability, good film-flexibility, chemical resistance, mechanical strength, hydrophobicity, non-toxicity and low cost. 6 Ethyl cellulose has been the subject of research activity for oxygen enrichment for several years; 7 however, only a few studies concerning the systematic investigation of gas/vapor transport through ethyl cellulose 32
Page 1 and 2: Synthesis, Characterization, and Ga
Page 3 and 4: Table of Contents General Introduct
Page 5 and 6: General Introduction cellulose deri
Page 7 and 8: General Introduction biogenetically
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: General Introduction Macromolecules
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
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 and 94:
91 Chapter 3 dendrons (G1-a-ІІ-G1
Page 95 and 96:
93 Chapter 3 (DMAP) as a base, as s
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(
Page 145 and 146:
143 Chapter5 as shown in Scheme 1,
Page 147 and 148:
145 Chapter5 in Table 1. The molecu
Page 149 and 150:
147 Chapter5 almost same pattern of
Page 151 and 152:
Conclusions Table 3. Thermal Proper
Page 153 and 154:
151 Chapter5 W.; Jing, X. J. Polym.
Page 155 and 156:
Chapter 5 Synthesis and Properties
Page 157 and 158:
Acknowledgments While submitting th
Page 159:
Synthesis, Characterization, and Ga
show all

Synthesis, Characterization, and Gas Permeation Properties

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?