Synthesis, Characterization, and Gas Permeation Properties

General Introduction
In conclusion, the author has successfully synthesized a number R'' of = novel
H
R =
R/HO
OH/R
C
H2 O
O
OH/R
+
cellulose derivatives appended with a variety of functional entities and has fully
characterized the resulting polymers by making use of IR and NMR spectroscopic
identification, elemental analysis, and molecular-weight determination etc. The
nature of the substituent played a dominant role in determining the solubility and
thermal characteristics of the polymers, for instance, the silylated and
perfluoroacylated polymers displayed inclination towards nonpolar solvents, those
with moderately polar G1 dendritic moieties were soluble in moderately polar solvents
and highly polar protic solvents while the augmented polarity in going to
G2-dendronized polymers imparted the relatively poor solubility characteristics. On
the other hand, the carbamoyl- and amino acid-functionalized polymers exhibited very
good organosolubility probably due to the presence of polar linkages along with the
bulky alkyl peripheries. As far as the thermal characteristics are concerned, the
dendron-functionalized ethyl cellulose derivatives exhibited the highest thermal
stability (T0, 295–325 °C) while the trifluoroacetylation conferred the polymers with
the greatest chain stiffness (3a; Tg, 227 °C). Furthermore, the gas permeation
characteristics were revealed to be a dynamic interplay of two intricate structural
features, i.e., local/segmental mobility and free space available inside the polymer
matrix, both sensitive to the nature (polarity), shape, and bulk of the side groups in the
present series of cellulose derivatives. In general, the trends in the permeability
22
in CH 2Cl 2
R''/R/HO
OH/R/R''
n
(9) (10)
CH 3
O
x
O
O
H
N
H
R'
O
OH
EDC.HCl/DMAP, r.t., 48 h
O
O
OH/R/R''
R' = H CH 3 (CH 3) 2CHCH 2 NH 2COCH 2 NH 2COCH 2CH 2 (CH 3) 3COCONH(CH 2) 4
10a 10b 10c 10d 10e 10f
DS Est = 3.0 3.0 1.1 1.0 1.7 3.0
O
O
H
N
H
R'
O
n