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Handbook of Size Exclusion Chromatography and Related ...

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The silylation was performed in LiCl/DMAc with a reagent mixture <strong>of</strong><br />

hexamethyldisilazane (HMDS) <strong>and</strong> chlorosilane. The obtained DS was 2.89 <strong>and</strong><br />

the cellulose derivative was reported to be completely soluble in THF. Both initial<br />

<strong>and</strong> fractionated TMSC were characterized using SEC.<br />

4.3 Cellulose Acetate<br />

Cellulose acetate is commercially one <strong>of</strong> the most important cellulose derivatives<br />

<strong>and</strong> is utilized, as, for example, fibers <strong>and</strong> filters. The application <strong>of</strong> the product is<br />

highly dependent on the DP as well as the DS <strong>of</strong> the derivative. The interest in<br />

characterization <strong>of</strong> cellulose acetate by SEC is thus primarily connected<br />

to commercial production rather than to the study <strong>of</strong> cellulose per se. Reported<br />

chromatographic conditions for various cellulose acetates are shown in Table 5.<br />

Table 5 SEC Conditions for Characterization <strong>of</strong> Cellulose Acetate Samples<br />

Cellulose<br />

sample<br />

Packing<br />

material<br />

<strong>Exclusion</strong><br />

limits <strong>of</strong><br />

each<br />

column (A ˚ ) a<br />

Solvent<br />

Temperature<br />

(8C)<br />

Flow<br />

rate<br />

(mL/min) Reference<br />

Diacetate — 3 10 3<br />

THF Ambient 1.0 110<br />

8 10 3<br />

10 5<br />

Diacetate Styragel 3 10 4<br />

10<br />

THF Ambient 1.0 111<br />

5<br />

3 10 6<br />

10 6<br />

Triacetate Styragel 7 10 5<br />

DCM Ambient 1.0 112<br />

5 10 6<br />

5 10 3<br />

2–5 10 3<br />

Diacetate TSK<br />

GMPWXL or<br />

CPG-10 or<br />

Toyopearl-75HW<br />

— Acetone — — 106<br />

Diacetate PL Gelþ 10 3<br />

DMAc b or 80 (DMAc) 1.5 104<br />

Shodex 10 4<br />

NMP b<br />

60 (NMP)<br />

A80M 10 5 þ<br />

one mixed<br />

DS 0.7–2.5 PL mixed B 3 linear 0.5% LiCl/ 60 1.0 105<br />

10 10 6<br />

DMAc<br />

a A ˚ ¼ 10 2 10 m, generally defined as the exclusion limit <strong>of</strong> polystyrene dissolved in THF.<br />

b With <strong>and</strong> without addition <strong>of</strong> 10 2 2 M LiCl or LiBr.<br />

© 2004 by Marcel Dekker, Inc.

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