Synthesis, Characterization, and Gas Permeation Properties

Chapter 3
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Chapter 3
Synthesis and Properties of Amide-Containing Dendrons and
Dendronized Cellulose Derivatives
Abstract
First and second generation amide-containing dendrons (G1-a-ІІ–G1-c-ІІ and
G2-a-ІІ–G2-c-ІІ) having branched alkyl periphery and focal carboxyl functionality
were synthesized via a convergent pathway and incorporated into ethyl cellulose.
Dendronized ethyl cellulose derivatives (2a–c, 3a–c) were synthesized in good yield
by the reaction of terminal carboxyl moiety of various dendrons with residual hydroxy
groups of ethyl cellulose (1; DSEt, 2.69). 1 H NMR spectra and elemental analysis
were employed to determine the degree of esterification (DSEst) of the resulting
polymers. The presence of the peak characteristic of the C=O group in the FTIR
spectra furnished further evidence for the incorporation of dendritic moieties into ethyl
cellulose. All of the derivatives (2a–c, 3a–c) were soluble in chloroform and
methanol, and the solubility window narrowed in going from G1- to G2-derivatized
polymers. The onset temperatures of weight loss of 2a–c (295–325 C°) and 3a–c
(312–320 °C) in air were slightly higher than 294 ºC, indicating that the thermal
stability was retained upon dendron functionalization. Free-standing membranes of 1
and 2a–c were fabricated, and 2a–c exhibited enhanced permselectivity for He/N2,
H2/N2, CO2/N2, and CO2/CH4 gas pairs as compared to 1.