Gas permselective composite membrane prepared by plasma polymerization coating techniques

A gas permselective hollow fiber membrane having an O.sub.2 /N.sub.2 gas permselectivity of greater than 2.3 comprising:

• a microporous hollow fiber substrate;
• and
• a gas permselective plasma polymerizate coating on the surface of the substrate,
• wherein the plasma polymerizate coating is formed from a lower alkyl substituted disiloxane monomer of molecular weight of not more than 165 according to the formula:
• ##STR5## wherein R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are individually selected from methyl and ethyl.

A gas permselective hollow fiber membrane having an O.sub.2 N.sub.2 gas permselectivity of greater than 2.3 comprising:

• a microporous hollow fiber substrate;
• and
• a gas permselective plasma polymerizate coating on the surface of the substrate;
• wherein the plamsa polymerizate coating is formed from the copolymerization of
• a disiloxane monomer, and
• a co-monomer selected from organo silanes, fluorocarbons and hydrocarbons.

A module for separating gaseous mixtures comprising:

• a shell means having spaced end portions and defining an elongated chamber therebetween,
• a plurality of individual gas permselective hollow fiber membranes having an O.sub.2 /N.sub.2 gas permselectivity of greater than 2.3,
• said membranes comprising a microporous hollow fiber substrate, and a gas permselective plasma polymerizate coating on the surface of the substrate, wherein the plasma polymerizate coating is formed from a lower alkyl substituted disiloxane monomer of molecular weight of not more than 165 according to the formula:
• ##STR6## wherein R.sub.1, R.sub.2, R.sub.3 and .sub.4 are individually selected from methyl and ethyl,
• wherein said membranes are exending in substantially parallel relationship spaced from each other within said shell means, said chamber being divided by the walls of said hollow fibers into an intracapillary space within said hollow fiber and an extracapillary space outside said hollow fibers, said intracapillary space and said extracapillary space communicating with each other only through the walls of said hollow fibers,
• means communicating with said extracapillary space for passing gaseous mixtures therethrough, and
• means communicating with said intracapillary space for removing permeate gas therefrom.

A module for separating gaseous mixtures comprising:

• a shell means having spaced end portions and defining an elongated chamber therebetween,
• a plurality of gas permselective hollow fiber membranes having O.sub.2 /N.sub.2 gas permselectivity of greater than 2.3,
• said membranes comprising a microporous hollow fiber substrate, and a gas permselective plasma polymerizate coating on the surface of the substrate, wherein the plasma polymerizate coating is formed from the co-polymerization of a disiloxane monomer, and a co-monomer selected from organo silanes, fluorocarbons and hydrocarbons,
• wherein said membranes are extending in substantially parallel relationship spaced from each other within said shell means, said chamber being divided by the walls of said hollow fibers into an intracapillary space within said hollow fibers and an extracapillary space outside said hollow fibers, said intracapillary space and said extracapillary space communicating with each other only through the walls of said hollow fibers,
• means communicating with said extracapillary space for passing gaseous mixtures therethrough, and
• means communicating with said intracapillary space for removing gaseous permeate therefrom.

A gas permselective hollow fiber membrane having an O.sub.2 /N.sub.2 gas permselectivity of greater than 2.3 comprising:

• a gas permselective plasma polymerizate coating on the surface of the substrate;
• wherein the plasma polymerizate coating is formed from a lower alkyl substituted disiloxane monomer of molecular weight of not more than 165 according to the formula:
• ##STR7## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are individually selected from methyl and ethyl;
• said gas permselective hollow fiber membrane prepared by a method comprising:
• moving said microporous substrate through a tubular plasma reactor;
• wherein the tubular plasma reactor has capacitively coupled external electrodes and a plasma glow zone controlled between the electrodes of the reactor;
• applying a radio frequency discharge to the electrodes of the reactor;
• introducing said lower alkyl substituted disiloxane monomer into the reactor in order to energize the monomer into a plasma controlled within the glow zone between the electrodes of the reactor;
• and
• depositing a gas permselective plasma polymerizate coating onto the surface of the microporous substrate moving through the glow zone.

A gas permselective hollow fiber membrane having an O.sub.2 /N.sub.2 gas permselectivity of greater than 2.3 comprising:

• a microporous hollow fiber substrate;
• and
• a gas permselective plasma polymerizate coating on the surface of the substrate;
• wherein the plasma polymerizate coating is formed from the copolymerization of:
• a disiloxane monomer;
• and
• a co-monomer selected from organo silanes, fluorocarbons and hydrocarbons;
• said gas permselective hollow fiber membrane prepared by a method comprising:
• moving said microporous substrate through a tubular plasma reactor;
• wherein the tubular plasma reactor has capacitively coupled external electrodes and a plasma glow zone controlled between the electrodes of the reactor;
• applying a ratio frequency discharge to the electrodes of the reactor;
• introducing said disiloxane monomer co-polymerized with said co-monomer into the reactor in order to energize the monomer and co-monomer into a plasma controlled within the glow zone between the electrodes of the reactor;
• and
• depositing a gas permselective plasma polymerizate coating onto the surface of the microporous substrate moving through the glow zone.

A method of making a gas permselective composite membrane, comprising:

• moving a microporous substrate through a tubular plasma reactor,
• wherein the tubular plasma reactor has capacitively coupled external electrodes and a plasma glow zone controlled between the electrodes of the reactor,
• applying a radio frequency discharge to the electrodes of the reactor,
• introducing an organo siloxane monomer, co-polymerized with a co-monomer selected from an organo siloxane, a fluorocarbon and a hydrocarbon into the reactor in order to energize the monomer and co-monomers into a plasma controlled within the glow zone between the electrodes of the reactor, and
• depositing a gas permselective plasma polymerizate coating onto the surface of a microporous substrate moving through the glow zone.