Synthesis, Characterization, and Gas Permeation Properties

More documents

Recommendations

Info

Perfluoroacylation of Ethyl Cellulose corresponding hydrocarbon polymers. 10b It is worth mentioning that the perfluoroalkanoylation resulted in an enhancement in the FFV values of polymer membranes (2a–d) regardless of the simultaneous increase in their density as compared to the starting material (1). For instance, 2c was observed to possess the highest fractional free volume (FFV is 0.197), in spite of its quite high density (ρ is 1.194) among all of the perfluoroacylated derivatives of 1, which probably indicates the formation of relatively sparse structures due to the incorporation of fluorine-containing moieties. Similar tendencies have been reported in F-containing polycarbonates. 12 Furthermore, it is a general trend that the bulky substituents sterically obstruct intersegmental packing, 9 and in the case of F-containing polymers chain packing is further restrained by the intermolecular repulsive forces resulting from the presence of fluorine atoms having high electron density. Table 5. Physical Properties of Polymers 1 and 2a–e polymer υw a (cm 3 /mol) ρ b (g/cm 3 ) FFV c 1 135.8 1.099 0.182 2a 145.0 1.155 0.185 2b 149.6 1.178 0.189 2c 154.2 1.194 0.197 2d 172.5 1.298 0.191 2e 150.9 1.206 0.161 a υw: van der Waals volume. b ρ: density. Determined by hydrostatic weighing. c FFV: fractional free volume. Estimated from membrane density. Gas Permeation Properties. The permeability coefficients of the membranes of polymers 1 and 2a–e to various gases measured at 25 °C are listed in Table 6, and their plot versus kinetic diameter of gases is shown in Figure 5. The gas permeability coefficients (P) of the perfluoroacylated derivatives (except 2e) were higher than that of 1, and approximately obey the following order: 2c > 2b ≈ 2d > 2a > 1 > 2e, which is in accordance with the FFV of the polymer membranes. The order 66
67 Chapter 2 of the gas permeability coefficients depends upon the shape, size, and mobility of the perfluoroacyl substituents. Table 6. Gas Permeability Coefficients (P) of Polymer Membranes at 25 o C polymer P (barrer) a He H2 O2 N2 CO2 CH4 PCO2/PN2 PCO2/PCH4 1 53 76 18 5.0 110 12 22 9 2a 72 102 28 8.0 172 17 21 10 2b 100 140 44 16 250 30 16 9 2c 114 155 52 20 284 37 14 8 2d 110 130 48 16 251 29 16 9 2e 40 51 11 3.0 64 6.0 22 11 a 1 barrer = 1x10 -10 cm 3 (STP) cm cm -2 s -1 cmHg -1 . In this study, it has been revealed that an optimum increase in the bulk or the length of the perfluoroalkanoyl group accompanies an enhancement in the gas permeability whereas an excessive increase affects conversely. For instance, the Figure 5. Gas permeability coefficients of ethyl cellulose (1) and its perfluoroacylated derivatives (2a–e) vs kinetic diameter of gases.
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 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
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: 65 Chapter 2 other fluorinated poly
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?