Gas permeation properties of poly(silamine) membrane

Abstract

The gas permeation characteristics of poly(silamine) membrane, which consists of alternating 3,3‐dimethyl‐3‐silapentane and N,N′‐diethylethylenediamine units in the main chain, were investigated. Though poly(silamine) shows high flexibility (glass transition temperature of −88°C), the gas permeabilities were much lower than those of other rubbery polymers such as poly(dimethylsiloxane) and natural rubber. The activation energies of diffusion in poly(silamine) were much higher than that of natural rubber. On the basis of these results, we propose a model such that the interaction between the Si atom and gas molecules (O2 and N2) prevents the free diffusion of the gas molecule in the poly(silamine) membrane. © 1997 John Wiley & Sons, Ltd.

Controlling the Photonic Properties of Cholesteric Cellulose Nanocrystal Films with Magnets

“…Therefore, the manipulation of the orientation of the helix m has so far not been addressed, or was at best limited to favor its vertical orientation uniformly across the sample. [28,30,31] While the use of external fields, such as electric [32][33][34] and magnetic, [29,[35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] have been shown to provide a powerful control over the CNC orientation in suspensions, they have been so far considered impractical as a tool to tailor the photonic pro perties of the films. More specifically, it has been believed for over two decades that the magnetic orientation of the cholesteric phase in CNC suspensions required always very strong fields (≥5 T), which probably discouraged many from investigating this method, due to the seemingly limited applicability and thus relevance of this technique to produce useful aligned CNC-based materials.…”