Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F2/00—Processes of polymerisation
  • C08F2/32—Polymerisation in water-in-oil emulsions
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
  • A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
  • A61L15/42—Use of materials characterised by their function or physical properties
  • A61L15/425—Porous materials, e.g. foams or sponges
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
  • C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
  • C08G65/26—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds
  • C08G65/2603—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds the other compounds containing oxygen
  • C08G65/2606—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds the other compounds containing oxygen containing hydroxyl groups
  • C08G65/2612—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds the other compounds containing oxygen containing hydroxyl groups containing aromatic or arylaliphatic hydroxyl groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
  • C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
  • C08G65/32—Polymers modified by chemical after-treatment
  • C08G65/329—Polymers modified by chemical after-treatment with organic compounds
  • C08G65/334—Polymers modified by chemical after-treatment with organic compounds containing sulfur
  • C08G65/3344—Polymers modified by chemical after-treatment with organic compounds containing sulfur containing oxygen in addition to sulfur
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/28—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum
  • C08J9/283—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum a discontinuous liquid phase emulsified in a continuous macromolecular phase
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K23/00—Use of substances as emulsifying, wetting, dispersing, or foam-producing agents
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K23/00—Use of substances as emulsifying, wetting, dispersing, or foam-producing agents
  • C09K23/02—Alkyl sulfonates or sulfuric acid ester salts derived from monohydric alcohols
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K23/00—Use of substances as emulsifying, wetting, dispersing, or foam-producing agents
  • C09K23/14—Derivatives of phosphoric acid
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K23/00—Use of substances as emulsifying, wetting, dispersing, or foam-producing agents
  • C09K23/16—Amines or polyamines
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D1/00—Detergent compositions based essentially on surface-active compounds; Use of these compounds as a detergent
  • C11D1/02—Anionic compounds
  • C11D1/12—Sulfonic acids or sulfuric acid esters; Salts thereof
  • C11D1/29—Sulfates of polyoxyalkylene ethers

Definitions

• This invention relates to water-in-oil high internal phase emulsions and porous polymeric materials produced therefrom.
• Water-in-oil emulsions are dispersions of discontinuous or discrete aqueous particles commonly referred to as the "internal" aqueous phase in a continuous or “external” oil phase. Emulsions can contain as much as and more than 70 volume percent internal phase. These are often referred to as high internal phase emulsions (HIPEs). The volume fraction of the internal aqueous phase in such emulsions can be as high as 90 percent and frequently is as high as 95 percent with some HIPEs being reported as high as 98 percent aqueous phase.
• HIPEs high internal phase emulsions
• the use of high internal phase emulsions (HIPEs) in forming porous polymeric materials is well known and is described, for example, in U.S. Patents 5,210,104; 5,200,433; 4,536,521 ; 4,788,225; 5,147,345; 5,331 ,015; 5,260,345; 5,268,224 and 5,318,554.
• the external oil phase typically comprises a vinyl polymerizable monomer, such as 2-ethylhexyl acrylate and styrene, and a cross-linking monomer such as divinylbenzene.
• the internal aqueous phase typically comprises water, a radical initiator (if not in the oil phase) and an electrolyte.
• a surfactant is added to the oil phase prior to emulsification.
• emulsion stabilizing surfactants include, for example, nonionic surfactants, such as sorbitan esters (for example, sorbitan monooleate and sorbitan monolaurate).
• sorbitan esters for example, sorbitan monooleate and sorbitan monolaurate
• stabilizing surfactants include certain poiyglycerol aliphatic esters such as those described in U.S. Patent No. 5,500,451.
• these known surfactants are not efficient, that is, they have to be used in high concentrations to stabilize HIPEs, which can increase the cost of making HIPE foams.
• these known surfactants When used at concentrations of less than about 2 weight percent, based on the weight of the oil phase, or about 0.06 weight percent based on the weight of the entire emulsion, these known surfactants do not stabilize a HIPE through polymerization to an open-celled foam.
• the emulsion stabilizing surfactant should be removed from the porous polymeric foam prior to use.
• the surfactant may be an extractable residue which can be removed through post-polymerization rinses. If not removed, the surfactant residue may create a problem when it comes in contact with sensitive human skin.
• this invention is a polyoxybutylene-polyoxyethylene sulfate- based surfactant.
• this invention is a water-in-oil high internal phase emulsion having at least 70 volume percent of an internal aqueous phase and less than 30 volume percent of an external oil phase, and an emulsion stabilizing polyoxybutylene- polyoxyethylene-based surfactant.
• this invention is a process for preparing a porous polymeric material which comprises polymerizing the water-in-oil high internal phase emulsion of the second aspect.
• this invention is an open-cell porous polymeric material prepared by the process of the third aspect.
• this invention is an open-cell porous polymeric material prepared from the water-in-oil high internal phase emulsion of the second aspect where the external oil phase comprises a vinyl polymerizable monomer and having a liquid capacity greater than about 70 percent of its saturated state volume and containing, after drying without squeezing out any aqueous phase and prior to any rinsing or washing, relatively small amounts of extractable surfactants.
• extractable surfactants means that less than about 5 percent by weight, preferably less than about 2 percent by weight, more preferably less than about 1 percent by weight and most preferably less than about 0.5 percent by weight surfactant, based on the weight of the polymer, can be extracted from the foam using simple rinses with water or typical solvents for the surfactants, such as, for example, methanol or isopropanol.
• this invention is an article containing the foam of the fourth aspect that is useful as, for example, an absorbent article, an acoustical modulating article, thermal insulating article, and/or a filtering article.
• the surfactants of the present invention are useful for preparing high internal phase emulsions with low levels of surfactant.
• Surfactant applications are broad and anyone skilled in the art would be able to identify a multitude of uses for the surfactants of this invention.
• the polymerizable surfactants of this invention which may also be useful in making latexes to, for example, reduce migratory surfactant, and/or enhance the shear stability.
• the polymerizable surfactants of this invention may also be useful for encapsulation of a phase dispersed into another with the polymerizable surfactant at the interface. By polymerizing the surfactants in the dispersion, the dispersed phase can become encapsulated.
• Poregens such as for example an inert surfactant which can be rinsed free after polymerization leaving pores in the polymer, may be used to help render the encapsulation porous, if desired.
• the HIPEs of the present invention are also useful in preparing low density polymeric foam materials.
• Highly hydrophilic foam materials made according to the present invention have a particularly useful application in the manufacture of diapers, or other articles which absorb or retain aqueous body fluids.
• the high internal phase emulsion (HIPE) of the present invention is a water- in-oil emulsion having greater than about 70 volume percent, more preferably, greater than about 90 volume percent and, most preferably, greater than about 95 volume percent of an internal aqueous phase and less than about 30 volume percent, more preferably, less than about 10 volume percent and, most preferably, less than about 5 volume percent of an external oil phase.
• HIPEs of as much as 98 volume percent or more of internal aqueous phase can be made by the present invention.
• the external oil phase comprises one or more vinyl polymerizable monomers and a cross-linking monomer.
• the internal aqueous phase comprises water. Typically, a water-soluble radical initiator is added in the aqueous phase. If an oil-soluble initiator is employed, it is added in the oil phase. Additionally, the HIPE comprises a polyoxybutylene-polyoxyethylene-based surfactant.
• Vinyl polymerizable monomers which can be employed in the practice of the present invention are any polymerizable monomer having an ethylenic unsaturation.
• the HIPEs are advantageously prepared from either or both (i) at least one monomer that tends to impart glass-like properties (glassy monomers) to the resulting porous polymeric material and (ii) at least one monomer that tends to impart rubber-like properties (rubbery monomers) to the resulting porous polymeric materials.
• the glassy monomers are, for the purposes of the present invention, defined as monomeric materials which would produce homopolymers having a glass transition temperature above about 40°C.
• Preferred glassy monomers include methacrylate-based monomers, such as, for example, methyl methacrylate, and styrene-based monomers, such as, for example, various monovinylidene aromatics such as styrene, o-methylstyrene, chloromethylstyrene, vinylethylbenzene and vinyl toluene. More preferred glassy monomers include styrene, o-methylstyrene, and chloromethylstyrene. The most preferred glassy monomer is styrene.
• the rubbery monomers are, for the purposes of the present invention, defined as monomeric materials which would produce homopolymers having a glass transition temperature of about 40°C or lower.
• Preferred rubbery monomers include alkyl esters of ethylenically unsaturated acids ("acrylate esters” or “methacrylate” esters), such as 2- ethylhexyl acrylate, butyl acrylate, hexyl acrylate, butyl methacrylate, lauryl methacrylate, isodecyl methacrylate and mixtures thereof; vinyl aliphatic and alicyclic hydrocarbons such as butadiene; isoprene; and combinations of these comonomers.
• acrylate esters alkyl esters of ethylenically unsaturated acids
• acrylate esters or “methacrylate” esters
• More preferred rubbery monomers include butyl acrylate, 2-ethylhexyl acrylate, butadiene, isoprene and combinations of these comonomers.
• the most preferred rubbery monomer is 2-ethylhexyl acrylate.
• the HIPE emulsion includes at least one glassy monomer and at least one rubbery monomer.
• the rubbery monomer provides the foams with flexibility and is used in an amount sufficient to allow compression, bending and twisting during processing, packaging, shipping, storing and use of articles containing such foams, as well as to allow the foam to remain thin until it absorbs liquid, if desired.
• the glassy monomer provides the foams with structural integrity and is used in an amount sufficient to minimize the incidence of foam tearing or fragmenting encountered when such foams are subjected to both dynamic and static forces such as, for example, when the wearer of a diaper containing the foam walks, runs, crawls or jumps.
• the ratio of the glassy monomer to the rubbery monomer generally ranges from 1 :25 to 1.5:1 , more preferably from 1 :9 to 1.5:1.
• the amount of the vinyl polymerizable monomers most advantageously employed depends on a variety of factors, such as the specific monomers, in general, the vinyl polymerizable monomer is used in an amount of from 50 to 100 weight percent, preferably from 80 to 95 weight percent, and most preferably from 85 to 93 weight percent, based on the total oil phase.
• Cross-linking monomers which can be employed in the practice of the present invention for preparing the HIPE include any multifunctional unsaturated monomers capable of reacting with the vinyl monomers.
• Multifunctional unsaturated cross-linking monomers include, for example, divinylbenzene, ethylene glycol dimethacrylate, 3-butylene dimethacrylate, trimethylolpropane triacrylate and allyl methacrylate. While the amount of cross-linking monomers most advantageously employed depends on a variety of factors, such as the desired polymer modulus, in general, the cross-linking monomer is used in an amount of from 0 to 50 weight percent, preferably from 5 to 20 weight percent, and most preferably from 7 to 15 weight percent, based on the total oil phase.
• Radical initiators which can be employed in the practice of the present invention for preparing the HIPE include the water-soluble initiators such as, for example, potassium or sodium persulfate and various redox systems such as ammonium persulfate together with sodium metabisulfite and oil-soluble initiators, such as, for example, azobisisobutyronitrile (AIBN), benzoyl peroxide, methyl ethyl ketone peroxide and di-2-ethyl- hexyl-peroxydicarbonate and lauroyl peroxide.
• AIBN azobisisobutyronitrile
• benzoyl peroxide methyl ethyl ketone peroxide and di-2-ethyl- hexyl-peroxydicarbonate and lauroyl peroxide.
• the initiator can be added to the aqueous phase or to the oil phase, depending on whether the initiator is water-soluble or oil-soluble.
• the initiator should be present in an effective amount to polymerize the monomers. Typically, the initiator can be present in an amount of from 0.005 to 20 weight percent, preferably from 0.1 to 10 weight percent and most preferably from 0.1 to 5 weight percent, based on the total oil phase.
• the internal aqueous phase can include a water-soluble electrolyte for aiding the surfactant in forming a stable emulsion, controlling porosity of the foam and/or enhancing the hydrophilicity of the resulting polymeric foam material if left as a residual component of the foam material.
• Water-soluble electrolytes which can be employed in the practice of the present invention include inorganic salts (monovalent, divalent, trivalent or mixtures thereof), for example, alkali metal salts, alkaline earth metal salts and heavy metal salts such as halides, sulfates, carbonates, phosphates and mixtures thereof.
• Such electrolytes include, for example, sodium chloride, sodium sulfate, potassium chloride, potassium sulfate, lithium chloride, magnesium chloride, calcium chloride, magnesium sulfate, aluminum chloride and mixtures thereof.
• Mono- or divalent salts with monovalent anions, such as halides are preferred.
• the electrolytes can be employed up to about 20, more preferably up to about 5 and most preferably up to about 1 weight percent, based on the total aqueous mixture.
• the internal aqueous phase can additionally comprise a non-electrolyte component, such as, for example, glycerin, as long as a HIPE can still be prepared and polymerized into a foam.
• a non-electrolyte component such as, for example, glycerin
• Surfactants which can be employed in the practice of the present invention for preparing the water-in-oil high internal phase emulsion include polyoxybutylene- polyoxyethylene-based surfactants.
• R, R', R" and R' are any organic, inorganic, or combination of organic and inorganic functionalities which do not prevent the compound from acting as a surfactant.
• (BO) m and (BO) p are polyoxybutylene blocks of "m” and “p” 1 ,2-butyleneoxide units, respectively;
• (EO) n is a polyoxyethylene block of "n” ethylene oxide units;
• X is a counterion and m, n, and p are independently integers greater than zero.
• R is propenyl benzyl, propyl benzyl, vinyl, allyl, linear or branched alkyl, or alkyl-substituted aryl
• R' is hydrogen
• R" and R'" are independently hydrogen, propenyl benzyl, propyl benzyl, vinyl, allyl, linear or branched alkyl or alkyl-substituted aryl.
• m is a positive number from 10 to 100, more preferably from 20 to 70 and, most preferably, from 20 to 40.
• n is a positive number from 1 to 100, more preferably from 1 to 70 and, most preferably, from 5 to 50.
• p is a positive number from 10 to 100, more preferably from 20 to 70 and, most preferably, from 20 to 40.
• R, (BO) m , (EO) n and X are as defined previously.
• nonionic polyoxybutylene-polyoxyethylene-based surfactants can be prepared by the standard anionic polymerization of monoepoxides, such as, for example, ethylene oxide and butylene oxide, using either a monohydroxyfunctional or dihydroxyfunctional initiator compound and a catalytic amount of a base, as described in "Polymer Syntheses (I)" Organic Chemistry Series Volume I, Stanley R. Sandier, Wolf Karo, 1974, p. 184-189.
• Polyether sulfates can be prepared through sulfation of the corresponding polyether alcohol using sulfamic acid as described in Organic Functional Group Preparations"; Organic Chemistry Series, Volume 12-111, Second Ed., Stanley R. Sandier, Wolf Karo, 1989, p. 148-149. Preparations of the aforementioned compounds are described in detail in the examples.
• sulfate-based surfactants tended to lose their efficiency, that is, more surfactant is required to form a HIPE, over time.
• sulfate is gradually cleaved over time through a hydrolysis process, producing an alcohol-terminated surfactant. Since sulfates are known to be hydrolytically unstable at a pH below 6 and at a pH above 10, such a hydrolysis can be controlled by controlling the pH of the surfactant.
• the sulfonated form of the surfactant (sulfate-terminated surfactant) has been found to be more efficient than the corresponding alcohol form (alcohol-terminated surfactant) represented, for example, by the formula:
• alcohol-terminated surfactants have been found to be nearly as efficient as the corresponding sulfate-terminated surfactants, such as when m and n in the above formula are 30 and 50, respectively, as demonstrated in Examples 14 to 21. These alcohol-terminated surfactants have also been found to demonstrate high efficiency in forming polymerized HIPE foams.
• the amount of surfactant used must be such that a water-in-oil high internal phase emulsion will form.
• the amount of surfactant needed varies with the specific surfactant and the type of formulation used. As little as about 0.125 weight percent, or- less, based on oil phase can be used. More generally, as little as about 0.25 weight percent based on oil phase can be used. Generally, up to about 25 weight percent or more, based on the oil phase, can be used, if desired.
• Methods for preparing water-in-oil emulsions are known in the art such as, for example, in U.S. Patents 4,522,953 and 5,210,104, and these methods can be employed in the practice of the present invention.
• the water-in-oil HIPE can be prepared in batches.
• the water phase is gradually added to a mixture of oil phase and surfactant while the mixture is being agitated. Agitation can be accomplished any number of ways including impeller-type agitation.
• water-in-oil HIPEs can be prepared in a continuous flow manner. Methods for continuous flow HIPE preparation are also well established in the literature. See, for example, U.S. Patents 4,018,426 and 5,198,472.
• the potassium salt of 2-allylphenol was formed from a 1 :1 molar mixture of potassium ethoxide and 2-allylphenol whereby the ethanol formed during the reaction was removed under high vacuum. Sequential alkoxylation of 1 ,2-butylene oxide (approximately 40 units per molecule) and ethylene oxide (approximately, an average of 5 units per molecule) was conducted utilizing the potassium salt of 2-allylphenol as initiator/catalyst in toluene at 120°C in a Parr reactor. During the course of the polymerization, the allylphenyl moiety undergoes base-catalyzed isomerization to the corresponding 2-propenylphenoxy compound.
• the resulting diblock copolymer was neutralized with dilute HC1 , filtered and the volatiles were removed by roto-evaporation.
• the diblock-copolymer was characterized by GPC and NMR. This 2-propenylphenoxypoly BO/EO-monol was heated in the presence of sulfamic acid and pyridine to form the corresponding pyridinium sulfate. This material was heated at 60°C under high vacuum to remove residual pyridine and other volatile components. The degree of sulfamation was determined by 1 H NMR spectroscopy
• Example 2 Open-celled Polymerized HIPE Foam using 0.25 weight percent Surfactant 1 Based on the Monomer Phase (0.0125 weight percent Based on Entire Emulsion)
• a monomer phase composed of 4.79 g 2-ethylhexyl acrylate, 1.05 g styrene, 1.64 g divinylbenzene (55 percent active) and 0.10 g lauroyl peroxide initiator was dissolved 0.0188 g of the surfactant from example 1.
• the components form a clear solution.
• An aqueous phase was prepared by dissolving 1.42 g calcium chloride dihydrate and 0.17 g potassium persulfate into 141.08 g deionized water. This aqueous phase was added dropwise to the monomer/surfactant solution while mixing in a 250-mL beaker using a 3-paddle agitator at 300 RPM.
• the resulting HIPE was placed into a dish covered with
• Another surfactant was prepared as described in Example 1 except the number of 1 ,2-butylene oxide units per molecule was approximately 30 and the number of ethylene oxide units per molecule was approximately 20.
• Example 4 Open-celled Polymerized HIPE Foam using 0.25 weight percent Surfactant 2 Based on Monomer Phase (0.0125 weight percent Based on
• a HIPE was prepared and polymerized as described in Example 2 except Surfactant 2 was used instead of Surfactant 1.
• Example 6 Open-celled Polymerized HIPE Foam using 0.12 weight percent
• a polymerized HIPE foam was prepared as described in Example 4 except 0.0095 g of Surfactant 3 was used instead of 0.0188 g of Surfactant 2.
• the resulting foam was soaked in isopropanol for 2 days and then squeezed free of the internal aqueous phase.
• the foam was open-celled, as determined by Scanning Electron Microscopy (SEM).
• a HIPE was prepared and polymerized as described in Example 2, except Surfactant 4 was used instead of Surfactant 1.
• the efficiency of Surfactants 1 to 4 was evaluated by determining the minimum amount of surfactant required to form a polymerized open-celled HIPE foam from a 95 percent internal phase HIPE.
• HIPE formulations were prepared with surfactant concentrations ranging from 0.125 to 30 weight-percent based on the weight of the monomer phase while maintaining a 95-weight percent internal phase.
• the internal phase comprises 4.79 g 2-ethylhexyl acrylate, 1.05 g styrene, 1.64 g divinylbenzene and 0.10 g lauroyl peroxide.
• the external phase comprised 141.08 g deionized water, 1.42 g
• the surfactants were generally tested first with the 1 -weight percent formulation (based on weight of monomer phase). If the l-weight percent formulation successfully produced a polymerized open-celled HIPE foam, the 0.5-weight percent formulation was tested next, and so on until a HIPE foam could no longer be produced using the emulsification and polymerization methods described in Example 2. If the l-weight percent recipe failed to produce a polymerized HIPE foam, the 2-weight percent formulation was tested, and so on, until a foam was produced using the emulsification and polymerization methods described in Example 2.
• surfactant A For comparative purposes, a known surfactant system (Surfactant A) comprising 75 percent sorbitan monooleate and 25 percent sorbitan trioleate was tested along with Surfactants 1 to 4. Surfactant A was prepared in accordance with the procedure described in Example 1 of U.S. Patent No. 5,260,345. The test results are summarized in Table II, using the ratings shown in Table I.
• the data in Table II show that the surfactants of the present invention were more efficient in forming HIPE foams compared to the known surfactant.
• the known surfactant system required 15-weight percent surfactant based on the weight of the monomer phase to form a foam, while the surfactants of the present invention produced a stable HIPE foam at a concentration of as little as 0.125 weight percent surfactant based on the weight of the monomer phase (0.0006 weight percent based on the entire HIPE).
• foams prepared with the surfactants of the present invention at a concentration of 0.125-weight percent surfactant, based on the monomer phase were open-celled, as determined by SEM.
• a monomer phase composed of 1.30 g 2-ethylhexyl acrylate, 0.28 g styrene, 0.45 g divinylbenzene (55 percent active) and 0.03 g lauroyl peroxide initiator was dissolved 0.22 g freshly prepared Surfactant 3 from Example 5.
• An aqueous phase was prepared by dissolving 2.42 g calcium chloride dihydrate and 0.28 g potassium persulfate into 239.3 g of deionized water. All but 53 g of the aqueous phase was slowly emulsified into the monomer/surfactant solution using a dropwise addition while agitating at 115 RPM using a 3-paddle mixer. A thick HIPE resulted.
• the HIPE was placed into a PyrexTM (trademark of
• each material (a-d) was isolated as the poly(BO/EO)-monol and a portion of each material (a-d) was sulfonated according to the procedure in Example 7. The following eight surfactants were obtained:
• X was either a pyridinium, ammonium, or a combination of both.
• the aqueous phase was added dropwise to the monomer solution while mixing at 300 RPM with a 3-paddle mixer.
• the emulsion was mixed an additional 2 minutes after all of the water was added to ensure homogeneity.
• the resulting high internal phase emulsion was placed into Pyrex dishes, covered with SaranTM Wrap, and placed in a forced-air oven at 95°C for 19.5 hours (overnight) to cure.
• the resulting foam can be squeezed free of the aqueous phase.

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