Synthesis, Characterization, and Gas Permeation Properties

General Introduction
strategy (G1-a-ІІ–G1-c-ІІ and G2-a-ІІ–G2-c-ІІ) and coalesced with ethyl cellulose
through ester linkage. All of the dendronized derivatives of ethyl cellulose (4a–c,
5a–c) displayed fair thermal stability and a considerable lowering of glass transition
temperature in comparison with the starting polymer, the latter being ascribable to the
fairly bulky nonpolar alkyl peripheries. An appreciably good solubility of
G1-functionalized polymers in CHCl3 rendered the free-standing membranes‟
fabrication feasible by solution casting. The incorporation of bulky dendritic
substituents into ethyl cellulose led to the more dense membrane structure with
attenuated fractional free volume, thus decrement in the gas permeability of polymer
membranes. However, an enhanced permselectivity for He/N2, H2/N2, CO2/N2, and
CO2/CH4 gas pairs was discerned.
H/EtO
OEt
Ethyl Cellulose
1
(DSEt = 2.69)
R' =
O
O
OEt/H
R
n
O
H
N
+
R O
HN
N
O
O
NH
In Chapter 4, synthesis of t-butylcarbamates O Oof
ethyl cellulose (1a: DSEt, 2.69,
O
N
OEt
DSCarb, 0.31; and 6a: RDSEt,
2.50, DSCarb, 0.50) and cellulose acetate (7a: DSAc, 2.46, O
N
O
O
H
NH
R'/EtO
O
N
OEt/R'
R
HN
R
R
O
O
HN
HN
O
R' OH
N
O O
G1-a-��–G1-c-��
20
G2-a-��–G2-c-��
OEt
EDC•HCl, DMAP O
in CH2Cl2, r.t., 48 h
R'/EtO
O
OEt/R'
(CH 3CH 2) 2CH
(CH 3CH 2CH 2) 2CH
n
Dendronized Ethyl Cellulose
4a–c
(DSTotal = 3.0)
(CH 3CH 2)(CH 3CH 2CH 2CH 2)CH
n
Dendronized Ethyl Cellulose
5a–c
(DSTotal = 3.0)
a
b
c