Synthesis, Characterization, and Gas Permeation Properties of Silylated Derivatives of Ethyl Cellulose

Abstract

Silyl ethers of ethyl cellulose (2a-f) were synthesized in good yields by the reaction of various chlorosilanes with residual hydroxy groups of ethyl cellulose. 1 H NMR and FTIR spectra of the silylated polymers furnished the evidence for complete substitution of hydroxy protons by the silyl groups. Silylated derivatives of ethyl cellulose (2a-f) were soluble in common organic solvents and displayed enhanced solubility in relatively nonpolar solvents due to the substitution of hydroxy groups. The onset temperatures of weight loss of the silylated derivatives (2a-f) in air were higher than 270 °C, indicating fair thermal stability. Free-standing membranes of 1 and 2a-f were fabricated by casting their toluene solution, and all the silylated derivatives (2a-f) exhibited enhanced gas permeability (P) as compared to that of ethyl cellulose ( 1). An increment in the size of the silyl group led to the decrement in gas permeability of the polymers, and trimethylsilyl derivative (2a) exhibited the highest P value. The P CO2 /P N2 permselectivity values of the polymers (2a-f) were observed to be in the range of 15-19. The data for 2a, 2b, and 2c were located above Robeson's upper bound, in the plot of permselectivity vs permeability for the CO 2 /N 2 gas pair (P CO2 vs P CO2 /P N2 ). Gas diffusion coefficients (D) increased upon silylation for all the six gases under study, while gas solubility coefficients (S) underwent a decline.

Synthesis, characterization, and gas permeation properties of the silyl derivatives of cellulose acetate

“…Such behavior can be explained in terms of the strong interaction of CO 2 with the hydroxy groups present in cellulose acetate prior to silylation. Similar effects have been observed in the case of silylated derivatives of ethyl cellulose [48], and poly(diphenylacetylene) membranes bearing hydroxy group in their side chain [49,50]. Fig.…”

Synthesis, characterization, and gas permeation properties of t-butylcarbamates of cellulose derivatives

“…The t-butylcarbamates of cellulose derivatives (1a-4a) possess both the aforementioned features and the local mobility of the side groups playing a dominant role resulted in the permeability enhancement which was quite substantial for cellulose acetate derivatives, especially for 4a. These results are quite in compliance with the previous ones describing a two times increase in the P values to arise from the silylation of ethyl cellulose (DS Et , 2.69), a four to five times enhancement for silylated cellulose acetate (DS Ac , 2.46), and a magnanimous augmentation of more than 30 times to result from the silylation of cellulose acetate (DS Ac , 1.80) [54,67].…”

Orthogonal reactivity of thiols toward chlorovinylsilanes: selective thiol-ene chemistry

“…Some applications of chlorosilanes include functional group protection, functionalizing silica surfaces and polymers, and polymer synthesis. [18][19][20][21] Moreover, this work further complements our previous efforts in exploiting selective reactions in organosilicon chemistry. 22 …”