The Dow Chemical Company

Robert D Mussell

David D Devore

Francis J Timmers

James C Stevens

Donald L Schmidt

Carey L Scortichini

Gene D Rose

Susan J Babinec

Lenore H Crawford

David R Wilson

Peter N Nickias

Robert K Rosen

Richard Allen Lundgard

David R Neithamer

Steven P Webb

Robert E LaPointe

Keith R Plowman

Ashish Sen

Timothy J Rehg

Carlos E Hinton

The present invention relates to a quick set composition and a method for preparing the composition. The composition comprises an aqueous sol of a polymer having a backbone that contains pendant cationic groups and pendant acid groups. The sol is prepared by forming a solution of a polymer that contains pendant cationic groups and pendant acid groups in an aqueous-based solvent that contains water and a suitable organic solvent and removing a sufficient amount of the organic solvent from the solution to form a composition characterized by being reversibly dissolvable and reconstitutable by addition and removal of a suitable organic solvent. The composition of the present invention provides quick-set films that can be prepared in the absence additional surface active agents and with a substantial absence of organic solvents.

Quick-set film-forming compositions

An electrochemical fuel cell having a membrane electrode assembly and a flow field adjacent thereto wherein the flow field comprises an electrically conductive porous material having a porosity of at least about 50 percent and a mean pore size of at least about 35 microns. This fuel cell is able to operate at relatively high current densities and relatively high voltages at reduced gas flow rates.

Macroporous flow field assembly

A bipolar separator plate for two electrochemical cells connected in series, the plate having two layers of a porous electronically conductive material having positioned therebetween a solid layer of a polymeric material having dispersed therein at least 1 percent by weight of a conductive filler, wherein the plate has an area resistivity of less than 1 ohm-cm.sup.2, and wherein the solid layer has a permeability of less than 50 .mu.Darcy (.mu.D).

Bipolar plates for electrochemical cells

A water-based polymer composition containing a polyvalent metal complex and a polymer having pendant strong cationic groups and weak acid salt groups forms fast dry-to-the-touch coatings that are resistant to water and many organic solvents. These coatings can be removed with ammonia-containing solvents.

Composition for preparing a solvent-resistant coating

Substantially permanent or removable coatings can be prepared from a composition comprising a polymer dissolved or dispersed in a multicomponent medium that contains water, a low-boiling polar organic solvent, and a high-boiling point solvent. The polymer is characterized by containing structural units formed from the polymerization of a polymerizable strong cationic monomer, a polymerizable acid monomer, and optionally a non-interfering monomer. The composition forms a dust-free and tack-free film that can be removed by a combination of water and an organic solvent. The film can also be made resistant to organic solvents as well as acids and bases with the addition of a crosslinking agent to the composition.

Multisolvent-based film-forming compositions

Described is a membrane electrode assembly having an ion exchange membrane, and at least two active layers positioned on the same side of the membrane; wherein the active layers containing catalytically-active particles and an ionomer; the average equivalent weights of the ionomers in the layers differ by at least 50; and the active layer positioned closest to the membrane contains the ionomer with the lower average equivalent weight. This membrane electrode assembly, when utilized in a fuel cell, provides a relatively high voltage at a given current density and gas flow rate.

Active layer for membrane electrode assembly

A composition comprising (a) catalytically-active particles, (b) an organic compound having a pKa of at least about 18 and a basicity parameter, .beta., of less than 0.66, and (c) a polymeric binder. Also described is a process for preparing a membrane/electrode assembly, which comprises the sequential steps of (i) applying a layer of the composition of the invention to a solid polymer electrolyte, a carbon fiber paper, or a release substrate; (ii) heating the composition under conditions sufficient to volatilize at least 95 percent of component (b); and (iii) positioning the composition in contact with the solid polymer electrolyte, if the composition was not applied directly to the solid polymer electrolyte, forming the membrane/electrode assembly thereby. It has been discovered that the composition and process of the invention, when used to prepare a membrane electrode assembly (MEA) having a solid polymer electrolyte, provides an MEA which provides a relatively high voltage at a given current density and gas flow rate in a fuel cell.

Electrode ink for membrane electrode assembly

A process for preparing an electronically-conductive thermoplastic composition having at least two phases, which includes (A) combining an amorphous or semi-crystalline thermoplastic polymer or miscible blend of polymers with an electronically-conductive carbon under conditions sufficient to disperse the conductive carbon, thereby forming a mixture having at least one phase, with at least 60 percent of the carbon dispersed in a first phase which comprises at least 90 percent by weight of the mixture; and (B) combining the mixture obtained from step (A) with an amorphous or semi-crystalline thermoplastic polymer or miscible blend of polymers, at least a portion of which is immiscible in the first phase, thereby forming a composition having at least two phases. Compositions prepared by this process are sufficiently conductive to be useful for a variety of applications, such as structural materials for applications requiring electromotively-paintable substrates.

Thermoplastic polymer compositions with modified electrical conductivity

Process for preparing a membrane/electrode assembly

Catalyst systems useful in addition polymerization reactions comprising a Group 4 metal complex and a silylium salt activating cocatalyst are prepared by contacting the metal complex with a silylium salt of a compatible, non-coordinating anion, optionally the silylium salt is prepared by electrochemical oxidation and splitting of the corresponding disilane compound.

Silylium cationic polymerization activators for metallocene complexes

Novel catalytic derivatives of titanium or zirconium complexes containing one and only one cyclic delocalized, anionic, .PI.-bonded group wherein the metal is in the +2 formal oxidation state and having a bridged ligand structure and an activating cocatalyst are useful as catalysts for polymerizing olefins, diolefins and/or acetylenically unsaturated monomers.

Titanium (II) or zirconium (II) complexes and addition polymerization

An electrochemical fuel cell having a membrane electrode assembly and a layer of an electrically conductive porous material adjacent thereto which has at least two portions with different mean pore sizes, wherein a first portion of the layer adjacent to the membrane electrode assembly has a porosity no greater than a second portion of the layer adjacent to the opposite side of the layer; the second portion has a porosity of at least about 82 percent; and the second portion has an mean pore size which is at least about 10 microns and at least ten times greater than the mean pore size of the first portion.

Flow field assembly for electrochemical fuel cells

A process for polymerizing olefins, diolefins and/or acetylenically unsaturated monomers using novel catalyst compositions comprising titanium or zirconium complexes containing one and only one cyclic delocalized, anionic, .pi.-bonded group wherein the metal is in the +2 formal oxidation state and having a bridged ligand structure, also referred to as constrained geometry complexes, and an activating cocatalyst.

Titanium (II) or Zirconium (II) complexes and addition polymerization

Group 4 metal complexes useful as addition polymerization catalysts are prepared by electrolysis of cyclopentadienyl metal complexes under inert electrolysis conditions.

Growing community of inventors

Midland, MI, United States of America

Robert D Mussell