Abstract: The disclosure concerns a polymer derived from melt extrusion of (i) 80 to 95 wt % polycarbonate; said polycarbonate having and endcap level of 45% to 80% and a branching level of 300-5,000 m comprising the following branching structures: (ii) 4.9 to 20 wt % polymethyl methacrylate; and (iii) 0.1 to 1.5 wt % of catalyst; wherein the polymer is transparent, and wherein transesterification occurs with at least a portion of the polycarbonate and the polymethyl methacrylate during melt extrusion.

Abstract: The invention is a thermosetting coating composition comprised of an aliphatic polycarbonate resin and a cross linker. The aliphatic polycarbonate resins are derived from hydroxyl containing compounds including 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD) and 1,4-cyclohexane dimethanol (CHDM). The coatings made of these polycarbonates exhibit exceptional toughness; they possess a high degree of hardness while maintaining a high level of flexibility/impact resistance. These polycarbonate resins also exhibited better hydrolytic stability as compared to their polyester counterparts.

Abstract: A method for preparing and resulting articles of manufacture comprising a substrate having a surface, a bulk beneath the surface, and a grafted polymer layer on the substrate surface, the substrate surface and the grafted polymer layer, in combination, constituting a modified surface having a fibrinogen adsorption of less than about 125 ng/cm2 in a fibrinogen binding assay in which the modified surface is incubated for 60 minutes at 37° C. in 70 ?g/mL fibrinogen derived from human plasma containing 1.4 ?g/mL I-125 radiolabeled fibrinogen.

Abstract: The invention relates to surface modifying macromolecules (SMMs) having high degradation temperatures and their use in the manufacture of articles made from base polymers which require high temperature processing. The surface modifier is admixed with the base polymer to impart alcohol and water repellency properties.

Abstract: Embodiments of the invention provide for paper mill equipment that can better withstand the conditions of a paper Mill. Embodiments encompass paper mill equipment that incorporate a polyurethane layer having a hysteresis value of less than 70% and a permanent set of less than 30%. The polyurethane layer includes a polyurethane produced by curing a mixed composition. The mixed composition includes at least a urethane prepolymer (A) and at least a curing agent (B) having an active hydrogen group (H). The urethane prepolymer (A) has at least one terminal isocyanate group and is obtained by reacting at least a polyisocyanate compound (a) with at least a polycarbonate diol compound (b) having a number average molecular weight of at least 1500 g/mol. The curing agent (B) includes at least an amine compound. The elastomer compositions are also useful to coat the acid pickling roller in the steel industry.

Abstract: Provided is a method for improving thermal stability of polypropylene carbonate and, more particularly, a method of end capping a molecular chain of polypropylene carbonate using a urethane group by adding isocyanates or diisocyanates to a polypropylene carbonate resin, which may optionally be a mixture containing tertiary polyol, so as to delay thermal degradation of the polypropylene carbonate at a high temperature, thereby securing desired thermal stability. Especially, the method capable of being easily applied to reactive extrusion after preparing the polypropylene carbonate has been proposed, thus simplifying production processes and ensuring economical advantages. Moreover, the above method does not deteriorate transparency and specific smoke density characteristics at combustion, which are advantages of the polypropylene carbonate.

Abstract: Provided is a resin composition based on polyalkylene carbonate for use as an adhesive film composition for glass lamination, and more particularly, to a resin composition in which a plasticizer and isocyanate are added to polypropylene carbonate or polyethylene carbonate as polyalkylene carbonate to introduce a urethane group. As such, the resin composition of the present invention can improve an adhesive strength by addition of isocyanate, and secure flexibility by using the plasticizer. In particular, an adhesive sheet based on polyalkylene carbonate can decompose a polymer laminate layer through simple heat treatment to fully collect glass when defects of glass lamination are generated, thereby reducing the loss of glass due to process failure, be stable to moisture so that transport, storage, and use thereof are not limited, and perform lamination even at a lower process temperature.

Abstract: The present invention provides polyurethanes including a reaction product of components including: (a) at least one isocyanate functional prepolymer including a reaction product of: (1) about 1 equivalent of at least one polyisocyanate; and (2) about 0.01 to about 0.5 equivalent of at least one polycarbonate polyol; and (b) about 0.01 to about 1 equivalent of at least one branched polyol having at least 3 hydroxyl groups; compositions, coatings and articles made therefrom and methods of making the same.

Abstract: This invention relates to compositions, and related compounds and methods, of conjugates of immunomodulatory agents and polymers or unit(s) thereof. The conjugates may be contained within synthetic nanocarriers, and the immunomodulatory agents may be released from the synthetic nanocarriers in a pH sensitive manner.

Abstract: The present invention relates to a supramolecular polymer comprising 1-50 4H-units, said supramolecular polymer being obtainable by reacting at least one monomeric building block with a prepolymer. The present invention further relates to articles or compositions comprising the supramolecular polymer, in particular articles or compositions selected from the group consisting of decorative, thermo-reversible, or self-healing coatings, adhesive compositions, sealing compositions, thickeners, gelators and binders.

Abstract: The thermosetting, non-polymeric coating composition includes at least one monomeric material having a plurality of carbamate and/or urea groups, at least one crosslinker reactive with the at least one monomeric material, and a sag control agent that is a crystalline reaction product of an amine and an isocyanate.

Abstract: A polycarbonate diol comprising repeating units represented by the following formula (A) and a terminal hydroxy group, 60-100 mol % of the repeating units represented by the formula (A) being repeating units represented by the following formula (B) or (C). The amount of the repeating units represented by the formula (B) is 60-100 mol % based on the total amount of the repeating units represented by the formula (A). The polycarbonate diol has a terminal primary OH ratio of 95% or higher. (A) (In the formula, R represents a C2-12 divalent aliphatic or alicyclic hydrocarbon.

Abstract: Disclosed herein are novel copolycarbonates containing repeating units A and B respectively of the formulae: (A) —[R1OC(?O)O]—, and (B) —[(R2O)n-C(?O)—O]—, wherein the molar ratio of units (A) to units (B) is in the range of from about 9:1 to about 1:9, and wherein R1 is a divalent C8 to C12 alicyclic group, and R2 is ethylene or propylene, and n is an integer ranging from 4 to 40. Also disclosed are silicone hardcoat compositions containing the copolycarbonates and their derivatives. Upon cure, these silicone hardcoat compositions exhibit improved flexibility as compared to that of the conventional hardcoats while at the same time maintain the abrasion resistance of conventional silicone hardcoats.

Abstract: The present invention provides polyurethanes including a reaction product of components including: (a) about 1 equivalent of at least one polyisocyanate; (b) about 0.05 to about 1 equivalents of at least one branched polyol having 4 to 18 carbon atoms and at least 3 hydroxyl groups; (c) about 0.01 to about 0.3 equivalents of at least one polycarbonate diol; and (d) about 0.1 to about 0.9 equivalents of at least one polyol different from the branched polyol and having 2 to 18 carbon atoms, wherein the reaction product components are essentially free of polyether polyol and the reaction components are maintained at a temperature of at least about 100° C. for at least about 10 minutes; compositions, coatings and articles made therefrom and methods of making the same.

Abstract: The subject matter of the present invention relates to a blend comprising an epoxy resin, a cyclic carbonate, and a hardener comprising a polyalkoxypolyamine, another amine, and a catalyst, to a process for producing said blend, to the use of the blend of the invention for producing cured epoxy resin, and also to an epoxy resin cured with the blend of the invention, and in particular to fiber-reinforced cured epoxy resins for use in rotor blades for wind turbines.

Abstract: Disclosed is a resin composition for a flexographic printing plate, comprising (Component A) a binder resin and (Component B) a compound represented by Formula (1) and/or Formula (2), Component B being contained at 1 to 50 parts by mass relative to 100 parts by mass of Component A, wherein in Formulae (1) and (2) R1 and R4 independently denote a hydrogen atom or a methyl group, R2 and R5 independently denote a divalent organic group having 1 to 20 carbons, and R3 and R6 independently denote a monovalent organic group having 1 to 20 carbons, R3 and R6 not comprising an ethylenically unsaturated group, a dialkoxysilyl group, or a trialkoxysilyl group.

Abstract: The present invention provides a crosslinking agent which is excellent in processing characteristics and crosslinking performance, and is capable of preventing staining of a molded product upon molding in a metal mold which tends to be induced when using the crosslinking agent together with a triallyl isocyanurate. The crosslinking agent of the present invention comprises an isocyanurate derivative represented by the following general formula (I): wherein R1 and R2 are each independently a hydrogen atom, a methyl group or an ethyl group; R4 to R13 are each independently a hydrogen atom or a methyl group; R3 is a hydrocarbon group having 1 to 3 carbon atoms which may have a substituent group; and n is an integer of 1 or 2.

Abstract: A modified polymer is provided herein, the modified polymer having the following formula: in which W1, W2, W3, W4, W5, W6, Z1, Z2, Z3, Z4, Z5, Z9?, R1, R2, R3, R4, R5, n1, n2, n3, n4, n5, and n6? are defined herein. The modified polymer is useful for delivering a polynucleotide to the cytoplasm of a selected tissue type or cell type.

Abstract: A novel polycarbonate diol is useful as a raw material for producing a polycarbonate diol-based polyurethane with a high degree of hardness, superior abrasion resistance, and superior hydrophilicity. The polyurethane is useful in paints, coating agents, synthetic leathers, artificial leathers, and highly-functional elastomers, or the like. The polycarbonate diol is also useful for producing an active-energy radiation curable polymer composition giving a cured film having superior contamination resistance and high degree of hardness. The curable polymer composition contains a urethane(meth)acrylate oligomer obtained from the polycarbonate diol. The polycarbonate diol is obtained, for example, by reacting two specific types of diols with diester carbonate in the presence of a transesterification catalyst. The catalyst has a metal of Group 1 or 2 on the periodic table. A metal content of the transesterification catalyst is 100 weight ppm or less.

Abstract: Methods of forming polycarbonate graft copolymers are provided. In particular, a polycarbonate polymer or copolymer containing allyl groups provides the backbone for the graft copolymer, and pendant chains are attached to the copolymer through the allyl groups. The graft copolymers exhibit a combination of high transparency, good graft levels, good scratch resistance, and/or good anti-fog properties.

Abstract: Embodiments of the invention provide for a polycarbonate polyol including the reaction product of at least one polyol composition and a carbonate. The polycarbonate is one of an amorphous liquid and an amorphous solid at room temperature. The polyol composition includes at least one of a mixture of 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol in a weight ratio from about 60:40 to about 5:95 and a polyol derived from a natural oil fatty acid or natural oil fatty acid methyl ester.

Abstract: The present invention relates to a polycarbonate of number average molecular weight from 500 to 10000, glass transition point from 30 to 80° C. and hydroxyl group value of 30 mg KOH/g or less and the use of said polycarbonate in a urethane modified resin used as an ingredient for the production of a toner or a developer for electronic copying purposes. The present invention also relates to a urethane modified resin obtainable by the reaction of a polymer mixture comprising a polycarbonate according to any of claims 1 to 5 and a polycondensed resin of glass transition point from 10 to 60° C. and hydroxyl group value from 20 to 100 mg KOH/g with a polyfunctional isocyanate compound wherein the ratio of polycarbonate and polycondensed resin is from 20:80 to 80:20 by weight and the molar ratio of isocyanate groups in the polyisocyanate compound to hydroxyl groups in the polymer mixture is between 0.4 to 1.

Abstract: Disclosed herein are novel copolycarbonates containing repeating units A and B respectively of the formulae: (A)—[R1OC(?O)O]—, and (B)—[(R2O)n-C(?O)—O]—, wherein the molar ratio of units (A) to units (B) is in the range of from about 9:1 to about 1:9, and wherein R1 is a divalent C8 to C12 alicyclic group, and R2 is ethylene or propylene, and n is an integer ranging from 4 to 40. Also disclosed are silicone hardcoat compositions containing the copolycarbonates and their derivatives. Upon cure, these silicone hardcoat compositions exhibit improved flexibility as compared to that of the conventional hardcoats while at the same time maintain the abrasion resistance of conventional silicone hardcoats.

Abstract: The method comprises chemical modification of an optionally metallized polymer surface, for example a polycarbonate surface or a polymethacryllate surface functionalized with amino groups, said surfaces being optionally metallized, by treating said polymer surface with a mercaptoalkanoic acid or the salts or derivates thereof. The surfaces obtained by said method may be used as solid supports for immobilizing biomolecules, such as nucleic acids, proteins or membranes.

Abstract: Provided is a method for improving thermal stability of polypropylene carbonate and, more particularly, a method of end capping a molecular chain of polypropylene carbonate using a urethane group by adding isocyanates or diisocyanates to a polypropylene carbonate resin, which may optionally be a mixture containing tertiary polyol, so as to delay thermal degradation of the polypropylene carbonate at a high temperature, thereby securing desired thermal stability. Especially, the method capable of being easily applied to reactive extrusion after preparing the polypropylene carbonate has been proposed, thus simplifying production processes and ensuring economical advantages. Moreover, the above method does not deteriorate transparency and specific smoke density characteristics at combustion, which are advantages of the polypropylene carbonate.

Abstract: The invention relates to the use of 2,5-diisocyanato-1,4:3,6-dianhydro-2,5-dideoxy-D-manitol (I), 2,5-diisocyanato-1,4:3,6-dianhydro-2,5-dideoxy-D-glucitol (II), and/or 2,5-diisocyanato-1,4:3,6-dianhydro-2,5-dideoxy-L-iditol (III).

Abstract: Disclosed are random copoly(phosphonate carbonate)s with the high molecular weight and narrow molecular weight distribution exhibiting a superior combination of properties compared to prior art.

Abstract: Embodiments according to the present invention relate to sacrificial polymer compositions that include polycarbonate polymers having repeat units derived from stereospecific polycyclic 2,3-diol monomers. The sacrificial polymer compositions also include an acid generator that is selected from at least one photoacid generator and/or at least one thermal acid generator. In addition, embodiments according to the present invention relate to a method of forming a structure that includes a three-dimensional space interposed between a substrate and an overcoat layer, and a method of temporarily bonding first and second substrates together, which make use of the polycarbonate polymers.

Abstract: Provided is to provide a photoelectric conversion device including an organic compound layer which contains polymer (a) having partial structures represented by the following formulae (1) and (2) respectively. In the formula, R1, R2, R3 each independently represent a hydrogen atom or an alkyl group having from 1 to 4 carbon atoms, X and Y each independently represent a divalent organic group having from 1 to 20 carbon atoms, a represents 0 or 1, and CT represents an organic group having a charge transportable skeleton.

Abstract: An alcohol-soluble, water-insoluble, disinfectant composition and a method of using the same for disinfecting and for providing a prolonged antimicrobial property to a variety of surfaces, including skin. The composition comprises an antimicrobial polymer that is capable of imparting an antimicrobial property to a surface without the use of a metal or metal-containing compound. The composition is applied to a surface and allowed to evaporate leaving a coating of antimicrobial polymer.

Abstract: Disclosed are novel carbonate block copolymers and methods of making the same. Some carbonate block copolymers include oligomeric carbonate blocks bonded to one or more silicon-containing non-carbonate block, wherein the silicon-containing non-carbonate block is comprised of a diamine moiety and the carbonate block is joined to the silicon-containing non-carbonate block through a urethane group. Other carbonate block copolymers include oligomeric carbonate blocks bonded to one or more non-silicon-containing non-carbonate block, wherein the non-silicon-containing non-carbonate block is comprised of a diamine moiety and the carbonate block is joined to the non-silicon-containing non-carbonate block through a urethane group. The carbonate block may include Bisphenol-A moieties. The diamine from which either the silicon-containing or non-silicon-containing non-carbonate block is derived may be primary, secondary or tertiary.

Abstract: Disclosed is a resin composition for disposable resin molded product, and a disposable resin molded product that enables preparation of a disposable resin molded product not only maintaining excellent mechanical properties but also having biodegradability entailing an environment-friendly feature. The resin composition for disposable resin molded product comprises a polyalkylene carbonate resin.

Abstract: The present invention aims to improve spin performance and abrasion resistance for a golf ball having a cover using a nonionic polyurethane as a resin component. The golf ball of the present invention is a golf ball including a core and a cover covering the core and in which the cover contains a nonionic polyurethane as a resin component and the nonionic polyurethane has a hard segment content of 24.5% to 34.7% by mass.

Abstract: The object of the present invention is to provide a golf ball which is even more excellent in abrasion-resistance, durability and moldability by using a polyurethane ionomer having a novel structure as a base resin of a cover. The golf ball of the present invention has a cover, and the cover comprises, as a base resin, a polyurethane ionomer containing a polycarbonate polyol as a constitutional component.

Abstract: This disclosure provides a medical device and a method of forming the medical device. The medical device comprises a coating comprising a type-one polymer and a type-two polymer. The type-one polymer comprises at least two different blocks, at least one L1 block with the formula ; and at least one L2 block with the formula Medical devices comprising these polymers, mixtures of these polymers with therapeutic agents, and methods of making these polymers and mixtures are within the scope of this disclosure.

Abstract: A hydroxy compound is provided whereby a polyurethane excellent in elongation property can be produced. A hydroxy compound represented by the formula B-Am, wherein A is a univalent group which has a terminal hydroxy group and a carbonate chain composed of an ether unit produced by ring-opening of a monoepoxide and a carbonyloxy unit [—OC(O)—] linked to each other, and B is a m-valent residue produced by removing all hydroxy groups from a polycarbonate having m hydroxy groups at the terminals, provided that —O—R— in the repeating unit [—OC(O)—O—R—] of the polycarbonate is an ether unit other than an ether unit produced by ring-opening of a monoepoxide.

Abstract: A crosslinker for polymerizing a film-forming material including an alkyl or aromatic compound comprising at least two functional groups reactive with a film-forming resin and at least one pendent group having a nonionic metal coordinating structure. Coating compositions can include a film-forming material and the crosslinker. The coating compositions can be used to coat a substrate, such as a metal substrate. Applied coating layers on substrates can be cured to form coating films.

Abstract: The invention provides a method comprising the steps of (i) reacting a water-soluble and non-peptidic polymer having two or more terminal hydroxyl groups with di(1-benzotriazolyl)carbonate to form a water-soluble and non-peptidic polymer having two or more 1-benzotriazolylcarbonate ester groups; and (ii) reacting the water-soluble and non-peptidic polymer having two or more 1-benzotriazolylcarbonate ester groups with a water-soluble and non-peptidic polymer having three or more primary amino groups under conditions effective to form a cross-linked polymer composition.

Abstract: A thermoplastic composition comprises a polycarbonate having repeating structural carbonate units of the formula (1): wherein at least 60 percent of the total number of R1 groups contain aromatic organic groups and the balance thereof are aliphatic, alicyclic, or aromatic groups; and wherein the polycarbonate comprises terminal groups derived from reaction with a cyanophenol of the formula wherein Y is a halogen, C1-3 alkyl group, C1-3 alkoxy group, C7-12 arylalkyl, C7-12 alkylaryl, or nitro group, y is 0 to 4, and c is 1 to 5, provided that y+c is 1 to 5; a branching agent; and a flame retardant. The compositions are useful in the manufacture of a wide variety of parts, particularly those having a thin wall.

Abstract: In various embodiments the present invention comprises 2,4,6-trisubstituted-1,3,5-triazine capping agents comprising one, two, or three leaving groups as substituents with any remaining substituents being essentially inert to reaction with a nucleophilic group on a polymer or monomer, or reactive with a nucleophilic group on a polymer or monomer at a slower rate than any leaving group. The invention also comprises polymers or monomers with nucleophilic groups capped with a triazine moiety. Still other embodiments of the invention comprise processes for capping nucleophilic groups in a polymer or monomer which comprises combining and reacting the polymer or monomer with a triazine-comprising capping agent.

Abstract: A flame retardant polycarbonate resin composition comprises 100 parts by weight of a polycarbonate resin (A), 0.01 to 3 parts by weight of a silicone compound (B) having a branched chain structure and organic functional groups, wherein said organic functional groups comprise (I) aromatic groups or (ii) aromatic groups and hydrocarbon groups (excluding aromatic groups), 0.5 to 20 parts by weight of a phosphazene compound (C), 0.01 to 2 parts by weight of an organometallic salt (D) and 0.01 to 2 parts by weight of a fiber-forming type fluorine-containing polymer (E). 5 to 25 parts byweight of titanium oxide (F) and 0.05 to 2 parts by weight of a poly(organo hydrogen sioxane) (G), per 100 parts by weight of a polycarbonate resin (A), may be further added.

Abstract: Crosslinkable polymeric materials are disclosed useful for the temporal stabilization of a poling-induced noncentrosymmetric host lattice containing guest nonlinear optical chromophores. The materials are also suitable as crosslinkable coatings in the absence of chromophores. Also disclosed is a method of crosslinking such polymeric material.

Abstract: Compounds exhibiting angiogenic properties incorporating the structure of Formula I: R3—NH—NH—C(?O)—R2—P—R1 ??(I) wherein P is a water-soluble, biodegradable polymer, R1 is hydrogen, lower alkyl, lower alkoxy or —R2—C(?O)—NH—NH—R3; each R2 is independently —CH2—, —NH— or O; and each R3 is independently hydrogen or a residue of a naturally occurring alpha-L-amino acid or dipeptide thereof. Polymer networks crosslinked with hydrazide compounds are also disclosed, together with implantable medical devices incorporating the compounds and crosslinked polymers, and angiogenesis-promoting treatment methods, including wound-treatment methods.

Abstract: A polymer blend consisting essentially of at least one thermoplastic polymer, and a polymer comprising structural units derived from a 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine is disclosed.

Abstract: A thiol-ene polymeric material is disclosed. The material is produced by the photopolymerization of reactants having thiol and olefin moieties. The material can incorporate encapsulated components, including cells. Additionally, the material can be derivatized by reacting the polymeric material with components such as proteins.

Abstract: In various embodiments the present invention comprises 2,4,6-trisubstituted-1,3,5-triazine capping agents comprising one, two, or three leaving groups as substituents with any remaining substituents being essentially inert to reaction with a nucleophilic group on a polymer or monomer, or reactive with a nucleophilic group on a polymer or monomer at a slower rate than any leaving group. The invention also comprises polymers or monomers with nucleophilic groups capped with a triazine moiety. Still other embodiments of the invention comprise processes for capping nucleophilic groups in a polymer or monomer which comprises combining and reacting the polymer or monomer with a triazine-comprising capping agent.

Abstract: A composition comprising a reaction product of a diisocyanate, a chain extension agent having at least difunctional reactivity with an isocyanate, and a material comprising a blend of i) a primary carbamate material having at least one functional group reactive with an isocyanate and at least one primary carbamate group or a group convertible to a primary carbamate group, and ii) a reaction product of the primary carbamate material with an extending agent, wherein at least one of i) the isocyanate groups of the diisocyanate have a different reactivity in relation to each other, and ii) at least two of the groups with reactivity with an isocyanate on the chain extension agent have a different reactivity in relation to each other.

Abstract: A golf ball comprising at least one thermoplastic, thermoset, castable, or millable material formed from a composition comprising at least one telechelic polycarbonate copolymer formed from at least one polyol telechelic and at least one carbonate-forming compound; wherein the polyol telechelic is a dimer diol having a structure of: where R is the same or different moieties chosen from hydrogen, alkyl, aryl, aralkyl, alicyclic, cycloalkyl, and alkoxy groups; x+y?8; and m+n?8; and wherein the dimer diol is mixed with at least one C3 to C12 aliphatic polyol before being reacted to the carbonate-forming compound.

Abstract: A silicon-based polycarbonate of formula (I): wherein R1, R2, R3, R4, R5, R6, R8 and R9 are the same or different and selected from hydrogen or an optionally substituted straight chain, branched or cyclic, saturated or unsaturated hydrocarbon radical; R7 is a divalent linking group or an optionally substituted straight chain, branched or cyclic, saturated or unsaturated by hydrocarbon radical; A is an endcapping group; n, y and z are integers of 0 or more; and x is an integer of 0 or more.

Abstract: Polyurethane powder coating compositions containing uretdione groups and curing at low temperatures are provided, along with processes for preparing such compositions, and their use as powder coatings, wherein the compositions generally contain: A) a uretdione-containing powder coating hardener derived from aliphatic, (cyclo)aliphatic, cycloaliphatic or aromatic polyisocyanates and hydroxyl-containing compounds, and having a melting point from 40 to 130° C., a free NCO content of less than 5% by weight, and a uretdione content of 6-18% by weight; B) a hydroxyl-containing polymer having a melting point from 40 to 130° C., and an OH number between 20 and 200 mg KOH/gram, and C) a catalyst of the formula [NR1R2R3R4]+[R5]?, in which R1-R4 simultaneously, or independently of one another, are alkyl, aryl, aralkyl, heteroaryl or alkoxyalkyl radicals, and each R1-R4 is aromatic, linear or branched, unbridged or bridged with other radicals, R1-R4.