Abstract: By performing photograft polymerization of functional monomers such that grafted chains will be introduced from the surface of a polymer base film into its interior without deteriorating its inherent characteristics and also by creating a multiplex crosslinked structure between the grafted chains and the base film under such conditions as to cause preferential radiation-induced crosslinking reaction, there is produced a polymer electrolyte membrane having high enough oxidation resistance and proton conductivity to be suitable for use in fuel cells.

Abstract: The invention relates to a fluorocarbon polymer material comprising a backbone with the following unit: wherein: Z is a quaternary ammonium group, Y1 and Y2 are each independently an oxygen heteroatom or a sulphur heteroatom, A is a fluorinated or perfluorinated straight chain having from 2 to 6 carbon atoms, R1 represents a phenyl or aryl group or a —CR2R3— group, and R4 is selected from the group consisting of a hydrogen atom, a straight or branched, cyclic or acyclic, alkyl or halogenated alkyl group, and a group represented by the following formula: m is an integer comprised between 0 and 10, preferably between 0 and 3; m?, n and r are integers, each independently equal to 0 or 1; and s is equal to 0 or 1, provided that when s is equal to 0, then R4 is different from the hydrogen atom.

Abstract: A method of forming an ionomeric membrane includes a step of reacting a first polymer in chlorosulfonic acid to form a first precipitate. The first precipitate comprising a polymer including a polymer unit having at least one —SO2Cl moiety attached thereto and includes a step of dissolving the first precipitate in a polar aprotic solvent to form the first solution. A polymeric membrane is then formed from the first solution such that the membrane includes the polymer unit having at least one —SO2Cl. The polymer including a polymer unit a polymer unit having at least one —SO2Cl is then reacted with a nucleophilic compound to form the polymeric membrane.

Abstract: A high molecular nanocomposite membrane for a Direct Methanol Fuel Cell (DMFC), and a Membrane-Electrode Assembly (MEA) and a methanol fuel cell including the same membrane. The high molecular nanocomposite membrane for a DMFC includes a Nafion® high molecular membrane in which hydrophobic silica nanoparticles made of a silane compound having a water repellent functional group are dispersed. Since the high molecular nanocomposite membrane for a DMFC has lower permeability of methanol than a commercially available Nafion® high molecular membrane, the MEA fabricated using the high molecular nanocomposite membrane has little crossover of reaction fuel at the negative electrode. In addition, the methanol fuel electrode fabricated using the MEA that includes the high molecular nanocomposite membrane can decrease fuel loss and voltage loss.

Abstract: For use in a DMFC, a proton-conducting membrane containing a proton-conducting host polymer and a functionalized fullerene having one or more proton accepting or proton donating functional groups selected from: >C[PO(OH)2]2; —PO(OH)2; —OH; —SO3H; —NH2; —CN; —HOSO3H; —COOH; —OPO(OH)2; and —OSO3 or a combination of two or more of these groups attached to the fullerene.

Abstract: Polymers including pendent hydrophobic groups and pendent proton transfer groups are shown to form nanostructured films exhibiting greatly increased proton conductivity compared with films prepared from corresponding polymers lacking hydrophobic groups. The polymers can include repeating units each of which has both a hydrophobic group and a proton transfer group. Alternatively, the polymers can be the product of copolymerizing a first monomer with at least one hydrophobic group and a second monomer with at least one proton transfer group. The polymers are useful for the preparation of fuel cell proton exchange membranes.

Abstract: An ion-conductive composite membrane and a method of manufacturing the same, the membrane including phosphate platelets, a silicon compound, and a Keggin-type oxometalate and/or Keggin-type heteropoly acid, wherein the phosphate platelets are three-dimensionally connected to each other via the silicon compound. An electrolyte membrane having an ion-conductive inorganic membrane or an ion-conductive organic/inorganic composite membrane effectively prevents crossover of liquid fuel without the reduction of ion conductivity in a liquid fuel cell, thereby allowing for the production of fuel cells having excellent performance.

Abstract: The invention relates to the field of polymer chemistry and relates to sulfonated polyarylene compounds such as can be used for example in ion exchange membranes in fuel cells, as well as a method for the production thereof and the use thereof. The object of the present invention is to disclose hydrolytically and thermally resistant sulfonated polyarylene compounds with a defined degree and position of sulfonation, from which membrane materials with an improved resistance to hydrolysis can be produced. The object is attained through sulfonated polyarylene compounds according to at least one of the general formulas (I)-(IV).

Abstract: Provided is a polymer composition containing an oxocarbon and a polymer, further, a polymer composition that the oxocarbon are expressed by formula (1).

Abstract: The present invention relates to a high temperature proton-conducting polymer membrane, a preparation method thereof, a membrane-electrode assembly using the same and a fuel cell containing the same. More particularly, it relates to a proton-conducting polymer membrane enabling fuel cell operation under high temperature and normal pressure condition, wherein sulfoalkyl or sulfoaryl groups are introduced between layers of metal phosphate and cation exchange groups are present in side chains, a preparation method thereof and a membrane-electrode assembly using the proton exchange membrane and a fuel cell containing the same.

Abstract: Triblock copolymers useful for forming ion conductive membranes are provided. The triblock copolymers are characterized by having either a hydrophobic-hydrophilic-hydrophobic or a hydrophilic-hydrophobic-hydrophilic polymer sequence that induces a microphase separated morphology. Variations in which the hydrophilic polymer sequence component includes either acid groups or salts of acid groups are also disclosed. Methods for forming an ion conductive membrane from the triblock copolymers are provided.

Abstract: A water insoluble additive for improving the performance of an ion-exchange membrane, such as in the context of the high temperature operation of electrochemical fuel cells. The insoluble additive comprises a metal oxide cross-linked matrix having proton conducting groups covalently attached to the matrix through linkers. In one embodiment, the metal is silicon and the cross-linked matrix is a siloxane cross-linked matrix containing silicon atoms cross-linked by multiple disiloxy bonds and having proton conducting groups covalently attached to the silicon atoms through alkanediyl linkers.

Abstract: Disclosed are a multi-block copolymer, its producing method and an electrolyte membrane using the same. The multi-block copolymer includes a hydrophobic block having a plurality of repeating units represented as chemical formula 1; and a hydrophilic block having a plurality of repeating units represented as chemical formula 2. The multi-block copolymer is acidified, and can be used to an electrolyte membrane and a fuel cell. The use of the multi-block copolymer as an electrolyte membrane ensures excellent dimensional stability.

Abstract: The invention relates to a process for the extrusion of thermoplastic polymers having alkaline ionic groups. The process consists in preparing a mixture composed of a thermoplastic polymer having alkaline ionic groups and a plasticizer, in extruding the mixture obtained to form a film; then in washing the film obtained in aqueous medium to remove said plasticizer(s). The plasticizer is chosen from non-volatile compounds which are stable with respect to the ionic groups of the polymer, which are soluble in water or in solvents that are miscible with water, said plasticizers being chosen from the compounds that react with the ionic group of the polymer via formation of a weak bond of the hydrogen bond-type, and the compounds that react with the ionic group of the polymer via formation of a strong bond, of the ionic bond-type.

Abstract: A process for producing a zeolite membrane comprising a seed crystal forming step of placing, in a pressure-resistant vessel, a seeding sol containing silica, water and a structure-directing agent and a support in a state that the support is immersed in the seeding sol and heating the heat-resistant vessel to form a zeolite seed crystal on the surface of the support, and a membrane formation step of allowing the zeolite seed crystal to grow to form a zeolite membrane on the surface of the support. In the seed crystal forming step, the molar ratio of water/silica in the seeding sol is set 10 to 50 and the heating of the pressure-resistant vessel is conducted at 90 to 130° C. The crystal c-axis of the present zeolite membrane is oriented in a direction vertical to the surface of the support and its thickness is uniform.

Abstract: The present invention provides a polymer electrolyte membrane with excellent proton conductivity in its thickness direction. Preferably, the polymer electrolyte membrane containing a polymer compound comprising an ionic segment having an ionic functional group and a nonionic segment having substantially no ionic functional group, and the phase containing ionic segments as a main component and the phase containing nonionic segments as a main component are phase-separated, and in the surface region thereof, the change in the amount of the ionic segment from the surface toward the interior substantially decreases monotonically.

Abstract: An organic/inorganic hybrid composite proton exchange membrane is provided. The proton exchange membrane includes an inorganic material of about 0.5-30 parts by weight and an organic material of about 99.5-70 parts by weight per 100 parts by weight of the proton exchange membrane. A surface area of the inorganic material is about 50-3000 m2/g. The organic material includes a sulfonated polymer or a phosphoric acid doped polymer.

Abstract: The present invention provides a method for producing a stabilized fluoropolymer which comprises producing the stabilized fluoropolymer by subjecting a treatment target substance containing a sulfonic-acid-derived-group-containing fluoropolymer to a fluorination treatment, wherein the sulfonic-acid-derived-group-containing fluoropolymer is a fluoropolymer containing —SO3M (in which M represents H, NR1R2R3R4 or M11/L; R1, R2, R3 and R4 are the same or different and each represents H or an alkyl group containing 1 to 4 carbon atoms; and M1 represents an L-valent metal), and the treatment target substance has a moisture content of not higher than 500 ppm by mass.

Abstract: The present invention provides a polymer, a polymer electrolyte and the use thereof. The polymer has, as a structural unit, a phenylene group in which two or three hydrogen atoms each have been substituted with a group represented by the following formula (A), and is insoluble in water: wherein A1 represents a group represented by formula (1a), formula (1b) or formula (1c) below, and the two or three A1 groups may be the same as or different from each other, wherein R10 and R11 each independently represents a hydrogen atom, an alkyl group of 1 to 20 carbon atoms, or an aryl group of 6 to 20 carbon atoms, R12 represents a hydrogen atom, an alkyl group of 1 to 20 carbon atoms, or an aryl group of 6 to 20 carbon atoms, M represents a metal ion or an ammonium ion, and in a case where M represents a divalent or higher-valent metal ion, M may be further bonded to another substituent.

Abstract: A multibranched polymer represented by the following formula (I), and a method for producing the multibranched polymer: where A represents an organic group having 3 or more branched chains, Xa represents a linking group containing any atom of Groups 14 to 16 in the Periodic Table, Y represents a functional group having a structure capable of having an active halogen atom, Q represents an arm moiety having a repeating unit derived from a polymerizable unsaturated bond, m1 represents any integer of 1 to the number of branched chains of A, m2 represents the number of branched chains of A, n1 represents an integer of 0 or 1 or more, and Ra represents an organic group that is not associated with the polymerization reaction.

Abstract: A proton conducting polymer includes a polymer backbone and a heterocyclic compound attached to the polymer backbone. The heterocyclic compound includes a sulfonyl functionality bonded to heterocyclic compound.

Abstract: Embodiments of the present disclosure encompass vinyl addition and ROMP polymers having at least one type of repeating unit that encompasses a comprise N+(CH3)3OH? moiety. Other embodiments in accordance with the disclosure include alkali anion-exchange membranes (AAEMs) made from one of such polymers, anion fuel cells (AFCs) that encompass such AAEMs and components of such AFCs, other than the AAEM, that encompass one of such polymers.

Abstract: This invention relates to novel chemical resistant, film forming, and moisture vapor permeable ionomers, including specialized polyurethane ionomers, polyurea ionomers, polyamide ionomers, polyester ionomers, or a mixture of the said ionomers, having high content of covalent-bonded ionic groups, total >100 milli-equivalents per 100 gram of ionomers. These specialized ionomers have low noxious chemical crossover rate, high moisture vapor transmission rate, hydrolytically stable in humid environment, and capable of forming thin films.

Abstract: A process for preparing a polymer comprising sulfonating a perfluorocyclobutane polymer with a sulfonating agent to form a sulfonated perfluorocyclobutane polymer, wherein the sulfonating agent comprises oleum, SO3 or a combination thereof is provided. A process for preparing proton exchange membranes and fuel cells comprising the proton exchange membrane are also provided.

Abstract: The present invention relates to a sulfonated poly(arylene ether) copolymer, a manufacturing method thereof and a polymer electrolyte membrane for fuel cell using the same.

Abstract: The present invention relates to a sulfonated poly(arylene ether) copolymer, a manufacturing method thereof and a polymer electrolyte membrane for fuel cell using the same.

Abstract: The invention relates to a process for the extrusion of thermoplastic polymers having acid ionic groups. The process consists in preparing a mixture composed of a thermoplastic polymer having acid ionic groups and a plasticizer, in extruding the mixture obtained to form a film, then in washing the film obtained in aqueous medium to remove said plasticizer(s). The plasticizer is chosen from non-volatile compounds which are stable with respect to the ionic groups of the polymer, which are soluble in water or in solvents that are miscible with water, said plasticizers being chosen from the compounds that react with the ionic group of the polymer via formation of a weak bond of the hydrogen bond-type, and the compounds that react with the ionic group of the polymer via formation of a strong bond, of the ionic bond-type.

Abstract: To provide a membrane and electrode assembly comprising a catalyst layer that improves water holding properties and exhibits high power generation characteristics even in low humidified conditions without inhibiting the diffusibility of reaction gas, the removal of the water generated by the electrode reaction, and its manufacturing method. There is provided a membrane and electrode assembly produced by sandwiching a polymer electrolyte membrane between a pair of catalyst layers, in which the catalyst layer comprises a polymer electrolyte and particles carrying a catalyst material, and in which the volume of fine pores having a diameter of 1.0 ?m or smaller is increased toward the polymer electrolyte membrane from the surface of the catalyst layer.

Abstract: A sulfonated poly(aryl ether) (SPAE) having a poly(aryl ether) (PAE) main chain and a sulfonated phenyl group pendent from the main chain are useful in proton exchange membranes (PEMs), particularly for fuel cells. The pendent phenyl group can provide an easily sulfonable site that may be sulfonated under mild conditions, providing the ability to precisely control the sulfonic acid content of the SPAE.

Abstract: An electrolyte membrane is prepared from a liquid composition comprising at least one member selected from the group consisting of trivalent cerium, tetravalent cerium, bivalent manganese and trivalent manganese; and a polymer with a cation-exchange group. The liquid composition is preferably one containing water, a carbonate of cerium or manganese, and a polymer with a cation-exchange group, and a cast film thereof is used as an electrolyte membrane to prepare a membrane-electrode assembly. The present invention successfully provides a membrane-electrode assembly for polymer electrolyte fuel cells being capable of generating the electric power in high energy efficiency, having high power generation performance regardless of the dew point of the feed gas, and being capable of stably generating the electric power over a long period of time.

Abstract: A polymer electrolyte membrane includes a cross-linking reaction product between a hydrophilic polymer and a cross-linking agent represented by Formula 1 below wherein R1 is substituted or unsubstituted C1-C20 alkyl group, substituted or unsubstituted C6-C20 aryl group, or substituted or unsubstituted C2-C20 heteroaryl group; and n is an integer in the range of 1 to 5. The polymer electrolyte membrane may be prepared by preparing a composition for forming a polymer electrolyte membrane including the hydrophilic polymer, the cross-linking agent represented by Formula 1 and a solvent, applying the composition for forming a polymer electrolyte membrane to a supporting substrate; and heat treating the composition for forming the polymer electrolyte membrane to form the polymer electrolyte membrane. A fuel cell or other device includes the polymer electrolyte membrane. The polymer electrolyte membrane has low solubility to a strong acid and excellent ionic conductivity.

Abstract: A cation-exchange membrane for electrolysis which comprises a fluoropolymer having ion-exchange groups and a porous base. It is characterized by having, on the anode-side surface of the membrane, protrusions comprising a polymer having ion-exchange groups. It is further characterized in that: when the average value of the heights of the tops of the protrusions from the anode-side surface of the membrane is expressed as h (?m), then 20?h?150; when the density of the protrusions distributed is expressed as P (protrusions per cm2), then 50?P?1,200; when the average proportion of the areas of those bottom parts of the protrusions which are on the same level as the anode-side surface of the membrane to the area of the anode-side surface of the membrane is expressed as S (cm2/cm2), then 0.001?S?0.6; and when the average proportion of the areas of the top parts of the protrusions to the area of the anode-side surface of the membrane is expressed as T (cm2/cm2), then T?0.05.

Abstract: A hydrophilic polymeric ionomer obtainable by reacting, in a solvent, components comprising a polymer and an ionic component selected from a strong acid or a strong base. The present invention also comprises methods of forming such membranes.

Abstract: A composition of matter is formed from a graftable polymer, having graftable sites onto which sidechains have been grafted. The sidechains include at least one silane group, and may be formed by polymerization of a polymerizable group of a silane precursor. These compositions may further include acid groups, and may be used, for example, in improved proton conducting materials in fuel cells.

Abstract: A method for preparing a nanocomposite ion exchange hydrogel and a nanocomposite ion exchange hydrogel are disclosed. A monomer is graft polymerized onto a carbohydrate to form a carbohydrate graft copolymer. Before, during, or after graft polymerizing, an adsorbent is modified with a cationic surfactant to form a surfactant modified adsorbent. Next, the surfactant modified adsorbent is dispersed and entrapped in the carbohydrate graft copolymer and crosslinked to form a crosslinked carbohydrate graft copolymer. The crosslinked carbohydrate graft copolymer is then isolated. In some embodiments, the pH of the crosslinked carbohydrate graft copolymer can be adjusted.

Abstract: Disclosed are sulfonated polymers of formula (I) or a salt thereof: wherein X is (a) or (b), R is hydrogen or an organic moiety, n is an integer from 10 to 10,000, p is 1 or 2, and m is 0 or 1 for a particular monomer unit such that the polymer has a degree of sulfonation of 0.50 or greater. Such polymers are useful in proton exchange membranes (PEMs) having high ion exchange capacity with higher proton conductivity than Nafion™, while having lower methanol permeability and lower water uptake than previously disclosed polymers.

Abstract: Membranes and processes for preparing membranes having weakly acidic or weakly basic groups comprising the steps of: (i) applying a curable composition to a support; (ii) curing the composition for less than 30 seconds to form a membrane; and (iii) optionally removing the membrane from the support; wherein the curable composition comprises a crosslinking agent having at least two acrylic groups. The membranes are particularly useful for producing electricity by reverse electrodialysis.

Abstract: The present invention provides polymer electrolyte membranes (PEM) based upon sulfonated poly 2-(phenyl ethyl)siloxane (SPPES) prepared in a one-pot procedure. This includes the SPPES homopolymer as well as random copolymer of SPPES with various non-sulfonated polysiloxanes. Copolymerization with poly 2-(phenyl ethyl)siloxane greatly improves the mechanical stability of the film compared to a SPPES homopolymer. Proton conductivity of the copolymer, though it is less than that of the homopolymer and Nafion, is comparable to other PEMs in the literature. Both SPPES based membranes show good water retention at temperature greater than 100° C., which indicates they may be suitable for use in high temperature PEM fuel cells.

Abstract: Solid acid/surface-hydrogen-containing secondary component electrolyte composites, methods of synthesizing such materials, electrochemical device incorporating such materials, and uses of such materials in fuel cells, membrane reactors and hydrogen separations are provided. The stable electrolyte composite material comprises a solid acid component capable of undergoing rotational disorder of oxyanion groups and capable of extended operation at a wide temperature range and a secondary compound with surface hydrogen atoms, which when intimately mixed, results in a composite material with improved conductivity, mechanical and thermal properties, when compared to pure solid acid compound.

Abstract: The present invention discloses a membrane for a fuel cell, comprising: a solid polymer electrolyte membrane composed of a crosslinked ion exchange resin, and a polymer having a weight-average molecular weight of 5,000 to 1,000,000 and having a charge group of polarity opposite to that of the ion exchange group of the ion exchange resin, which polymer is adhered onto at least one surface of the solid polymer electrolyte membrane in an amount of 0.0001 to 0.5 mg/cm3, preferably in a state that, when the membrane for fuel cell is immersed in a 50 mass % aqueous methanol solution of 30° C.

Abstract: A method for producing a polymer electrolyte membrane for electrolyte fuel cells includes: irradiating gamma rays onto a polymer substrate to obtain a crosslinked polytetrafluoroetylene substrate, grafting a styrenic monomer and bis(vinylphenyl)ethane as monomers to the crosslinked polymer substrate, and introducing sulfonic acid groups into graft side chains formed by grafting. Fluoro polymer substrates such as polytetrafluoroethylene and ethylene tetrafluoroethylene copolymer may be used.

Abstract: The present invention discloses a novel method to improve the selectivities of polybenzoxazole (PBO) membranes prepared from aromatic polyimide membranes for gas, vapor, and liquid separations. The PBO membranes that were prepared by thermal treating aromatic polyimide membranes containing between 0.05 and 20 wt-% of a poly(styrene sulfonic acid) polymer. These polymers showed up to 95% improvement in selectivity for CO2/CH4 and H2/CH4 separations compared to PBO membranes prepared from corresponding aromatic polyimide membranes without a poly(styrene sulfonic acid) polymer.

Abstract: Disclosed is a solid polymer electrolyte membrane obtained by graft-polymerizing one or more kinds of radically polymerizable monomers to a resin membrane which is irradiated with radiation. This solid polymer electrolyte membrane is characterized in that at least one kind of the radically polymerizable monomers is a monofunctional monomer having one alkenyl group and a plurality of aromatic rings. By using a monofunctional monomer having one alkenyl group and a plurality of aromatic rings as at least one kind of the radically polymerizable monomers for radiation graft polymerization, there can be obtained a solid polymer electrolyte membrane having good oxidation resistance. When this solid polymer electrolyte membrane is used as an electrolyte membrane of a fuel cell, the fuel cell can have a long life since a grafted polymer chain is hardly decomposed.

Abstract: Highly energy efficient electrodialysis membranes having low operating costs and a novel process for their manufacture are described herein. The membranes are useful in the desalination of water and purification of waste water. They are effective in desalination of seawater due to their low electrical resistance and high permselectivity. These membranes are made by a novel process which results in membranes significantly thinner than prior art commercial electrodialysis membranes. The membranes are produced by polymerizing one or more monofunctional ionogenic monomers with at least one multifunctional monomer in the pores of a porous substrate.

Abstract: An aromatic-polyether-type ion conductive polymer membrane having improved mechanical strength is provided. An aromatic-polyether-type ion-conductive ultrahigh molecular weight polymer having an ion exchange capacity of 0.1 meq/g or higher and a structure comprising an aromatic-polyether-type ultrahigh molecular weight polymer in which an acid group introduced, said aromatic-polyether-type ultrahigh molecular weight polymer having at least one structural unit selected from those represented by the following formulas (1) and (2) and the sum of the number a of the structural unit of the formula (1) and the number b of the structural unit of the formula (2) being 2 or larger: Ar1—Om—Ar1??(1) Ar2—On—Ar2??(2).

Abstract: A polymer membrane composition for a fuel cell, a polymer membrane prepared therefrom, a membrane electrode assembly, a fuel cell including the same, and associated methods, the polymer membrane composition including a polymer, the polymer including a cation exchange group and a carbon double-bond-containing cross-linkable group, a (meth)acryl-based compound, the (meth)acryl-based compound including a cation exchange group, and a polymerization initiator.

Abstract: A method is provided, comprising: copolymerizing a monomer comprising at least two amide groups, a monomer of formula (a) and a sulfonic acid or salt monomer, wherein R1 is CH3 or H. A polymer made by the method is provided. A method for coating an electrode is provided, comprising: providing an electrode; providing a solution of a free radical initiator, a monomer comprising at least two amide groups, a monomer of formula (a) and a sulfonic acid or salt monomer; wetting the electrode with the solution; and heating the wetted electrode; whereby the monomer comprising at least two amide groups, the monomer of formula (a), and the sulfonic acid or salt monomer are copolymerized; wherein R1 is CH3 or H. An electrode coated by the method is provided.

Abstract: An ion exchange membrane is prepared from a block copolymer comprising a hydrophobic polymer segment and a polar polymer segment. The ion exchange membrane is formed by placing a film layer in steam, water or an electric field at a temperature greater than about 40° C. for sufficient amount of time to develop a bicontinuous morphology. The ion exchange membrane is also formed from a film layer comprising a block copolymer and a solvent. The film layer is placed in an electric field at an elevated temperature and dried therein. The film layer is thereby converted into an ion exchange membrane with bicontinuous morphology. The ion exchange membrane prepared according to these processes exhibits improved mechanical and electrochemical properties.

Abstract: An ion exchange membrane (52) for a fuel cell comprises a polymer having an acid functional group normally including protons, and having alkali metal ions partially ion-exchanged with the protons of the acid functional group of the membrane. The partial ion exchange of alkali metal ions into the membrane relates either to patterning of the exchanged ion make-up of the membrane, with some being ion exchanged and some not, or to the extent or concentration of the ion exchange in any particular location, or to both.

Abstract: Solid and liquid compositions containing particles of highly fluorinated ion-exchange polymer having sulfonate functional groups with an ion exchange ratio of less than about 33. The compositions contain at least about 25% by weight of polymer particles having a particle size of about 2 nm to about 30 nm.