Synthesis, Characterization, and Gas Permeation Properties
Synthesis, Characterization, and Gas Permeation Properties
Synthesis, Characterization, and Gas Permeation Properties
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104<br />
Dendronization of Ethyl Cellulose<br />
Figure 6. Plot of SCO2 vs DCO2 of ethyl cellulose (1) <strong>and</strong> its dendronized<br />
derivatives (2a–c).<br />
accompanied a decrease in the gas solubility coefficients as well; e.g., the SCO2 of 1<br />
<strong>and</strong> 2a–c were 27.3 <strong>and</strong> 16.3–18.6 while the SN2 values being 1.1 <strong>and</strong> 0.5–0.6,<br />
respectively, in the units of 10 3 cm 3 (STP) cm -3 cmHg -1 . The reduction in the S<br />
values can be accounted for by the attenuated fractional free volume of the<br />
dendronized polymers (2a–c), as summarized in Table 4.<br />
In the glassy polymeric membranes, generally the D value undergoes a<br />
decrease with increasing critical volume of gases, whereas the S value experiences an<br />
increase with increasing critical temperature of gases. 28a Similar tendencies were<br />
observed in the D <strong>and</strong> S values of the polymer membranes of 1 <strong>and</strong> its dendronized<br />
derivatives; e.g., in the case of 2a, the diffusivity of CH4 was the lowest <strong>and</strong> that of O2<br />
was the highest (1.0 <strong>and</strong> 4.8 10 7 cm 2 s -1 , respectively) while CO2 displayed the highest<br />
solubility <strong>and</strong> N2 the lowest (16.3 <strong>and</strong> 0.5 10 3 cm 3 (STP) cm -3 cmHg -1 , respectively).<br />
The diffusion coefficients of this new family of dendron-functionalized cellulosics
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