Composite semipermeable membrane

A flexible, layered composite semipermeable membrane comprising:

• (a) a flexible film of a microporous material having a polar molecular vapour transmission rate in excess of 10,000 gms/m.sup.2.multidot. 24 hours, and an advancing polar liquid contact angle exceeding 90 degrees, and
• (b) a continuous, hydrophilic layer penetrated to an extent into the face of said hydrophobic layer and physically attached thereto, said composite membrane having a transmission rate of a polar vapour exceeding 80 percent that of said material alone, wherein said hydrophilic layer is an essentially odorless solid polyether polythioether, comprised of the free radical chain extended reaction product of:
• (a) a terminally unsaturated polyether polyene comprising the formula:
• R--[O--CH.sub.2 CH.sub.2 --O--(CH.sub.2).sub.m CH.dbd.CH.sub.2 ].sub.x,
• wherein m=O or 1 and x.gtoreq.2;
• (b) a polyether polythiol component comprising the formula:
• ##STR13## wherein y.gtoreq.2;
• (c) a free radical initiator;
• and
• (d) a suitable energy source,
• wherein R is polyoxyethylene.

A synthetic polymer comprising an essentially odorless solid polyether polythioether comprised of the free radical chain extended reaction product of:

• (a) a terminally unsaturated polyene comprising the formula:
• R--[(CH.sub.2).sub.m CH.dbd.CH.sub.2 ].sub.x,
• wherein m=O or 1 and x.gtoreq.2;
• (b) a polythiol component comprising the formula:
• ##STR14## wherein n=0 or 1, R'=H or OH and y.gtoreq.2;
• (c) a free radical photoinitiator;
• and
• (d) a suitable energy source,
• wherein at least one R is polyoxyethylene and the other R may be polyoxyethylene or a polyvalent organic moiety free from hydrolytically sensitive functional groups and other carbon-to-carbon unsaturation or thiol functional groups.

A synthetic polymer comprising an essentially odorless solid polyether polythioether, comprised of the free radical chain extended reaction product of:

• (a) a terminally unsaturated polyether polyene comprising the formula:
• R--[O--CH.sub.2 CH.sub.2 --O--(CH.sub.2).sub.m CH.dbd.CH.sub.2 ].sub.x,
• wherein m=0 or 1 and x.gtoreq.2;
• (b) a polyether polythiol component comprising the formula:
• ##STR15## wherein y.gtoreq.2;
• (c) a free radical photoinitiator;
• and
• (d) a suitable energy source, wherein R is polyoxyethylene.

A photocurable chemical formulation comprising (a) a terminally unsaturated polyene component comprising the formula:

• R--[(CH.sub.2).sub.m CH.dbd.CH.sub.2 ].sub.x,
• (a) a terminally unsaturated polyene component comprising the formula:
• R--[(CH.sub.2).sub.m CH.dbd.CH.sub.2 ].sub.x,
• wherein m=0 or 1 and x.gtoreq.2;
• (b) a polythiol component comprising the formula:
• ##STR16## wherein n=0 or 1, R'=H or OH and y.gtoreq.2;
• and (c) a free radical initiator;
• wherein at least one R is polyoxyethylene and the other R may be polyoxyethylene or a polyvalent moiety free from hydrolytically sensitive functional groups and other carbon-to-carbon unsaturation or thiol functional groups.

A photocurable chemical formulation comprising

• (a) a terminally unsaturated polyether polyene component comprising the formula:
• R--[O--CH.sub.2 CH.sub.2 --O--(CH.sub.2).sub.m CH.dbd.CH.sub.2 ].sub.x,
• wherein m=0 or 1, R =polyoxyethylene and x.gtoreq.2;
• (b) a polyether polythiol component comprising the formula:
• ##STR17## wherein y.gtoreq.2 and R=polyoxyethylene;
• and (c) a free radical initiator.

A method for forming a flexible, layered composite semipermeable membrane comprising the steps of:

• (a) forming a flexible layer of a microporous hydrophobic material having a water vapour transmission rate exceeding 10,000 gms/m.sup.2.multidot. 24 hours and an advancing polar liquid contact angle exceeding 90 degrees,
• (b) casting a flowable liquid formulation comprising:
• (1) a terminally unsaturated polyene component comprising the formula:
• R--[(CH.sub.2).sub.m CH.dbd.CH.sub.2 ].sub.x,
• wherein m=0 or 1 and x.gtoreq.2;
• (2) a polythiol component comprising the formula:
• ##STR18## wherein n=0 or 1, R'=H or OH and y.gtoreq.2;
• and (3) a free radical initiator;
• wherein at least one R is polyoxyethylene and the other R may be a polyoxyethylene or a polyvalent moiety free from hydrolytically sensitive functional groups and other carbon-to-carbon unsaturation or thiol functional groups,
• to form a continuous layer directly onto said microporous hydrophobic layer, the rheology of said liquid being such that, with sufficient hydraulic pressure applied, controllable penetration of said liquid into the microporous hydrophobic layer is achieved,
• (c) applying said hydraulic pressure
• (d) followed by curing of said liquid to form a continuous solid polymeric hydrophilic layer impregnated to an extent into the pores of said microporous hydrophobic layer, said composite membrane having a water vapour transmission rate exceeding 80 percent that of said hydrophobic layer alone.

A method for forming a flexible, layered composite semipermeable membrane comprising the steps of:

• (a) forming a flexible layer of a microporous hydrophobic material having a water vapour transmission rate exceeding 10,000 gms/m.sup.2.multidot. 24 hours and an advancing polar liquid contact angle exceeding 90 degrees,
• (b) casting a flowable liquid formulation comprising:
• (1) a terminally unsaturated polyether polyene comprising the formula:
• R--[O--CH.sub.2 CH.sub.2 --O--(CH.sub.2).sub.m CH.dbd.CH.sub.2 ].sub.x,
• wherein m=0 or 1, R=polyoxyethylene and x.gtoreq.2;
• (2) a polyether polythiol component comprising the formula:
• ##STR19## wherein y.gtoreq.2 and R=polyoxyethylene;
• and (3) a free radical initiator, to form a continuous layer directly onto said microporous hydrophobic layer, the rheology of said liquid being such that, with sufficient hydraulic pressure applied, controllable penetration of said liquid into the microporous hydrophobic layer is achieved,
• (c) applying said hydraulic pressure
• (d) followed by curing of said liquid to form a continuous solid polymeric hydrophilic layer impregnated to an extent into the pores of said microporous hydrophobic layer, said composite membrane having a water vapour transmission rate exceeding 80 percent that of said hydrophobic layer alone.