Non-reactive process for fixing nanotubes in a membrane in through-passage orientation

摘要

A polymer membrane is formed around nanotubes by applying either droplets or a thin film of a suspension of the nanotubes over a layer of a solution of the polymer, the suspending medium for the nanotubes and the solvent(s) for the polymer selected such that the suspending agent will evaporate while it is migrating into and dispersing in the solvent. When the polymer is then permitted to coagulate around the nanotubes, the coagulated polymer will fix the orientations of the nanotubes and a high proportion of the nanotubes will protrude from both sides of the resulting membrane to provide through-passages through the membrane.

主权项

1. A process for the formation of a membrane-supported nanotube array comprising open-ended nanotubes embedded in, and extending through, a membrane to form conduits from a first side of said membrane to a second side thereof, said process comprising:
(a) forming a layer of liquid polymer solution comprising a polymer dissolved in a nonaqueous solvent, said layer having an exposed surface; (b) applying to said exposed surface a nanotube suspension comprising a liquid suspension of open-ended nanotubes in a liquid suspending medium that is miscible with said nonaqueous solvent; (c) incubating said layer of liquid polymer solution with said nanotube suspension on said exposed surface to cause said liquid suspending medium to simultaneously dissolve in said polymer solution and at least partially evaporate; and (d) after said liquid suspending medium that has not evaporated in (c) has dissolved in said polymer solution, contacting said layer with an aqueous liquid to solidify said polymer into a nanotube-containing polymer skin with open-ended nanotubes embedded therein and extending therethrough, wherein said liquid suspending medium is a mixture of a first organic liquid and a second organic liquid, both said first and second organic liquids being miscible with each other and with said nonaqueous solvent, both said first and second organic liquids having normal boiling points below 200° C., and said first organic liquid having a boiling point lower than the boiling point of said second organic solvent by 50 to 125 degrees, and step (c) comprises incubating said substrate, liquid layer, and suspension to cause said first organic liquid to evaporate while said second organic liquid dissolves in said liquid solution of said polymer.