Showing papers on "Polymerization published in 1994"

Cationic zirconocene olefin polymerization catalysts based on the organo-Lewis acid tris(pentafluorophenyl)borane. A synthetic, structural, solution dynamic, and polymerization catalytic study

Abstract: We have isolated and systematically studied the structural and chemical properties of a series of electron-deficient cationic zircocene alkyl and hydrido complexes with high olefin polymerization activities. The single crystal X-ray diffraction-derived solid state and NMR-derived solution structures of these complexes correlate well with each other and afford considerable insight into the nature of these species. Through the use of the novel organoborane, we have, for the first time, unambiguously demonstrated the role of the key metallocene-cocatalyst interaction that has been proposed for MAO, alkyl aluminum halides, and dehydroxylated alumina. 56 refs., 10 figs., 19 tabs.

Mesoscale polynucleotide amplification device and method

Abstract: Disclosed are devices for amplifying a preselected polynucleotide in a sample by conducting a polynucleotide polymerization reaction. The devices comprise a substrate microfabricated to define a sample inlet port and a mesoscale flow system, which extends from the inlet port. The mesoscale flow system includes a polynucleotide polymerization reaction chamber in fluid communication with the inlet port which is provided with reagents required for polymerization and amplification of a preselected polynucleotide. In one embodiment the devices may be utilized to implement a polymerase chain reaction (PCR) in the reaction chamber (PCR chamber). The PCR chamber is provided with the sample polynucleotide, polymerase, nucleoside triphosphates, primers and other reagents required for the polymerase chain reaction, and the device is provided with means for thermally controlling the temperature of the contents of the reaction chamber at a temperature controlled to dehybridize double stranded polynucleotide, to anneal the primers, and to polymerize and amplify the polynucleotide.

Dispersion Polymerizations in Supercritical Carbon Dioxide

Abstract: Conventional heterogeneous dispersion polymerizations of unsaturated monomers are performed in either aqueous or organic dispersing media with the addition of interfacially active agents to stabilize the colloidal dispersion that forms. Successful stabilization of the polymer colloid during polymerization results in the formation of high molar mass polymers with high rates of polymerization. An environmentally responsible alternative to aqueous and organic dispersing media for heterogeneous dispersion polymerizations is described in which supercritical carbon dioxide (CO2) is used in conjunction with molecularly engineered free radical initiators and amphipathic molecules that are specifically designed to be interfacially active in CO2. Conventional lipophilic monomers, exemplified by methyl methacrylate, can be quantitatively (>90 percent) polymerized heterogeneously to very high degrees of polymerization (>3000) in supercritical CO2 in the presence of an added stabilizer to form kinetically stable dispersions that result in micrometer-sized particles with a narrow size distribution.

Observation of crystalline C3N4.

Abstract: We present strong experimental evidence suggesting that we have synthesized the \ensuremath{\beta}-${\mathrm{C}}_{3}$${\mathrm{N}}_{4}$ phase. This is a material predicted by theory to have bulk moduli comparable to diamond. Thin films containing small crystals were deposited on Si and Ge wafers by rf diode sputtering of a pure graphite target with pure ${\mathrm{N}}_{2}$. The crystal structure of these phases was investigated using x-ray and electron-beam diffractometry as well as transmission electron microscopy. Our results indicate that the \ensuremath{\beta}-${\mathrm{C}}_{3}$${\mathrm{N}}_{4}$ particles with typical dimensions of \ensuremath{\sim}0.5 \ensuremath{\mu}m are embedded in a 1-\ensuremath{\mu}m-thick layer of a C-N polymer. These particles are believed to crystallize preferentially on Si (100) wafers.

Voltammetric DNA Biosensor for Cystic Fibrosis Based on a Modified Carbon Paste Electrode

Abstract: Carbon paste electrodes modified by the inclusion of either octadecylamine or stearic acid were used as solid phases to which DNA was covalently bound. Immobilized DNA was detected by voltammetry of solutions containing submillimolar quantities of Co(bpy)3(ClO4)3, Co(phen)3(ClO4)3, and Os(bpy)3-Cl2 (bpy = 2,2'-bipyridine; phen = 1,10-phenanthroline), all of which associate reversibly with immobilized DNA and yield increased peak currents at DNA-modified electrodes. Immobilization onto octadecylamine-modified electrodes was performed using a water-soluble carbodiimide, and at high DNA concentrations in the reaction mixture, it resulted in visible polymerization of DNA on the surface. Optimization of the deoxyguanosine- (dG-) selective immobilization reaction for stearic acid-modified electrodes, using water-soluble carbodiimide and N-hydroxysulfosuccinimide reagents to activate carboxylate groups on the surface, yielded conditions of 4.5% (w/w) stearic acid and 10 micrograms/mL DNA. Polythymidylic acid of 4000-base average length (poly(dT)4000) was immobilized at stearic acid-modified electrodes following enzymatic elongation with dG residues at the 3'-end. These DNA-modified electrodes were used to study hybridization with analyte poly(dA)4000 by in situ voltammetry of 60 microM Co(bpy)3(ClO4)3 at low ionic strength (20 mM NaCl), and by voltammetry of the same complex, following exposure of the electrode to poly(dA)4000 in a separate hybridization step conducted at high ionic strength (0.5 M NaCl). Results indicate slow (> or = 1 h) hybridization at low ionic strength and fast (< or = 10 min) hybridization at high ionic strength.(ABSTRACT TRUNCATED AT 250 WORDS)

The kinetics of poly( N -isopropylacrylamide) microgel latex formation

Abstract: Conversion versus time curves were measured for poly(N-isopropylacrylamide) microgel latexes prepared by polymerization in water with sodium dodecyl sulfate, SDS. Polymerization rates increased with temperature with methylenebisacrylamide crosslinking monomer consumed faster thanN-isopropylacrylamide. The particle diameter decreased with increasing concentrations of SDS in the polymerization recipe and there was evidence that the rate of polymerization increased somewhat with SDS concentration. Particle formation occurred by homogeneous nucleation as micelles were absent.

Macromolecular Complexes in Chemistry and Biology

Abstract: I. Hydrophobically Associating Polymers.- 1 Synthesis and Characterization of Hydrophobically Associating Water-Soluble Polymers.- 1.1 Introduction.- 1.2 Synthesis.- 1.3 Copolymerization.- 1.4 Postpolymerization Modification.- 1.5 Characterization-Hydrophobe Incorporation.- 1.6 Summary.- 1.7 References.- 2 Analysis of Hydrophobically Associating Copolymers Utilizing Spectroscopic Probes and Labels.- 2.1 Introduction.- 2.2 Emission Probes and Labels.- 2.3 Absorption Probes.- 2.4 Concluding Remarks.- 2.5 References.- 3 Solution Properties of Hydrophobically Associating Water-Soluble Polymers.- 3.1 Introduction.- 3.2 Polymer Systems.- 3.3 Solubility Characteristics.- 3.4 Solution Stability.- 3.5 Solution Rheological Properties.- 3.6 Summary.- 3.7 References.- 4 Aggregation of Hydrophobically Modified Polyelectrolytes in Dilute Solution: Tonic Strength Effects.- 4.1 Introduction.- 4.2 Experimental.- 4.3 The Polymers.- 4.4 Dilute Solution Viscosity.- 4.5 Fluorescence Spectroscopy.- 4.6 Intrinsic Viscosity.- 4.7 Concluding Remarks.- 4.8 References.- 5 Microdomain Composition in Two-Phase Hydrogels.- 5.1 Introduction.- 5.2 Background.- 5.2.1 Microphase Separation in Polymers.- 5.2.2 Importance of Graft Polymers.- 5.3 Results.- 5.3.1 Hydrogels from Surfactant Solutions.- 5.3.2 Hydrogels from Ethanol/Water Solutions.- 5.3.3 Solute Uptake by Gels.- 5.4 Conclusions.- 5.5 References.- 6 Molecular Association and Polymerization of 1-Alkyl-4-vinylpyridinium Ions.- 6.1 Complexation in 1-Alkyl-4-vinylpyridinium Ions and Related Polymers.- 6.2 Homopolymerization of 1-Alkyl-4-vinylpyridinium Ions.- 6.3 Copolymerization of 1-Alkyl-4-vinylpyridinium Ions.- 6.4 Conclusion.- 6.5 References.- 7 Fluorocarbon-Modified Water Soluble Polymers.- 7.1 Introduction.- 7.2 Experimental.- 7.3 Results and Discussion.- 7.4 Conclusions.- 7.5 References.- II. Polyelectrolyte Complexes.- 8 Static Light Scattering of Polyelectrolyte Complex Solutions.- 8.1 Introduction.- 8.2 Survey of Static Light Scattering Studies on PEC Solutions.- 8.3 Interpretation of Light Scattering Experiments.- 8.4 Experimental.- 8.4.1 Materials.- 8.4.2 Methods of Investigation.- 8.5 Results and Discussion.- 8.6 Conclusion.- 8.7 References.- 9 Interaction Between Oppositely Charged Low Ionic Density Polyelectrolytes: Complex Formation or Simple Mixture?.- 9.1 Introduction.- 9.2 Material and Techniques.- 9.2.1 Polymer Synthesis.- 9.2.2 Polymer Characterization.- 9.2.3 Other Techniques.- 9.3 Phase Diagram.- 9.3.1 Phase Diagram Representation.- 9.3.2 Influence of the Charge Density.- 9.3.3 Influence of the Ionic Strength.- 9.3.4 Influence of the Molecular Weight of the Samples.- 9.3.5 Phase Diagram and Complex Formation.- 9.4 Polymer-Polymer Affinity and Phase Diagram.- 9.5 Conclusion.- 9.6 References.- 10 Basic Properties of Soluble Interpolyelectrolyte Complexes Applied to Bioengineering and Cell Transformations.- 10.1 Introduction.- 10.2 Kinetic and Equilibrium Properties of Interpolyelectrolyte Complexes.- 10.3 Interpolyelectrolyte Complexes as Protein Carriers.- 10.4 Complexes of DNA with Synthetic Polycations for Cell Transformation.- 10.5 Conclusion.- 10.6 References.- 11 Conformation Presumption for Polysaccharide-Polylysine Complexation.- 11.1 Introduction.- 11.2 Complex Formation.- 11.3 Pectate-Polylysine Interaction.- 11.4 Polyguluronate Rich Alginate-Polylysine Interaction.- 11.5 Polymannuronate Rich Alginate-Polylysine Interaction.- 11.6 Conclusion.- 11.7 References.- 12 Interpolymer Complexes and their Ion-Conduction.- 12.1 Introduction.- 12.2 Classification of Interpolymer Complexes.- 12.3 Formation of Interpolymer Complexes from PAA with POE.- 12.4 Thermodynamics of Interpolymer Complexes from PAA (or PMMA) with POE.- 12.5 Selective and Substitution Interpolymer Complexation.- 12.6 Solid Properties of a Hydrogen-Bonding Complex.- 12.7 Ion Conduction and Solid Polymer Electrolytes.- 12.8 Ion Conduction of Hydrogen-Bonding Complexes.- 12.9 References.- 13 Fluorescence Probe Studies of Poly(acrylic acid) Interchain Complexation Induced by High Shear Flow and Influence of Cationic Surfactants on the Complexation.- 13.1 Introduction.- 13.2 Experimental.- 13.2.1 Materials.- 13.2.2 Flow Processing.- 13.2.3 Fluorescence Measurements.- 13.3 Results and Discussion.- 13.3.1 Drag Reduction (DR) and PAA Conformation.- 13.3.2 Local Chain Rigidity.- 13.3.3 Hydrophobic Association.- 13.3.4 Hydrophobe-Assisted Rigidity.- 13.4 References.- III. Biopolymer Systems.- 14 Water-Soluble Biospecific Polymers for New Affinity Purification Techniques.- 14.1 Introduction.- 14.2 Discrimination on the Basis of High Molecular Weight.- 14.2.1 Biospecific Ultrafiltration.- 14.2.2 Biospecific Gel Filtration.- 14.3 Discrimination on the Basis of High Density of Charges: Affinophoresis.- 14.4 Discrimination on the Basis of Surface Tension Properties: Affinity Partition.- 14.5 Discrimination on the Basis of Reversible Solubility: Affinity Precipitation.- 14.6 Advantages and Drawbacks of Techniques Involving Water-Soluble Biospecific Polymers.- 14.7 References.- 15 Protein-Polyelectrolyte Complexes.- 15.1 Introduction.- 15.2 Investigation Methods.- 15.3 Factors Influencing Protein-Polyelectrolyte Complexation and Structures of the Protein-Polyelectrolyte Complexes.- 15.4 Protein Separation by Polyelectrolytes.- 15.5 Enzymes in Polyelectrolyte Complexes.- 15.6 Conclusion.- 15.7 References.- 16 Precipitation of Proteins with Polyelectrolytes: Role of Polymer Molecular Weight.- 16.1 Introduction.- 16.2 Materials and Methods.- 16.3 Results and Discussion.- 16.4 Conclusions.- 16.5 References.- 17 Complex Coacervation: Micro-Capsule Formation.- 17.1 Introduction and Terminology.- 17.2 Simple Coacervation.- 17.3 Complex Coacervation.- 17.4 Theory of Complex Coacervation.- 17.5 Coacervation as a Method of Microencapsulation.- 17.6 Materials and Methods.- 17.7 Results.- 17.8 Conclusions.- 17.9 References.- 18 Complexation of Proteins with Polyelectrolytes in a Salt-Free System and Biochemical Characteristics of the Resulting Complexes.- 18.1 Introduction.- 18.2 Experimental Section.- 18.3 Results and Discussion.- 18.4 Conclusions and Topics for Future Research.- 18.5 References.- IV. Ionomers in Solution.- 19 Ionomer Solutions: Polyelectrolyte or Ionomer behavior.- 19.1 Introduction.- 19.2 Sulfonated Polystyrene Ionomer Solutions in Nonpolar Solvents.- 19.3 Sulfonated Polystyrene Ionomer Solutions in Polar Solvents.- 19.4 Perfluorinated Ionomer Solutions.- 19.5 Conclusion.- 19.6 References.- 20 Scattering Studies of Ionomer Aggregates in Nonpolar Solvents.- 20.1 Introduction.- 20.2 Experimental.- 20.3 Light Scattering Analysis.- 20.4 Results and Discussion.- 20.5 References.

Diffusion Model of Hologram Formation in Dry Photopolymer Materials

Abstract: The diffusion equation is solved in the low-order harmonic approximation, in order to describe the grating formation process in dry photopolymer materials. We describe how the ratio between diffusion and polymerization rates controls the process of grating formation. Nonlinearity and reciprocity failure are predicted. Experimental results are also shown which are in qualitative agreement with the theory.

Kinetic evidence of reaction diffusion during the polymerization of multi(meth)acrylate monomers

Abstract: The polymerization behavior and reaction kinetics for a series of multifunctional (meth)acrylate monomers were experimentally characterized and modeled with particular attention focused on the importance of the reaction diffusion mechanism in these polymerizations. In general, reaction diffusion was found to be the primary mechanism for termination beginning as low as 5% double-bond conversion. Termination mechanisms in linear systems have been found to become reaction diffusion controlled, but not until much higher conversions, 40-50%. Evidence of reaction diffusion included a significant plateau in the termination kinetic constant and strict proportionality of k p and k t , at higher conversion (>10%) for all monomers studied

Polymerization catalyst systems, their production and use

Abstract: This invention is generally directed toward a supported catalyst system useful for polymerizing olefins The invention particularly relates to a supported metallocene catalyst system that does not require an activator or cocatalyst for the polymerization of olefins

Toward real applications of conductive polymers

Abstract: The chemical polymerization of pyrrole in the presence of textile substrates results in the formation of electrically conducting, polypyrrole coated fabrics. Applications of these materials include microwave attenuation, static charge dissipation, and EMI shielding. The degradation kinetics of the electrical conductivity of these materials has been investigated and found to proceed by multiple rate laws. In the initial stages of conductivity loss, a diffusion controlled mechanism predominates, where oxygen diffusion into the polypyrrole film is rate limiting. At longer times, the degradation follows a simple first-order decay. The dopant anion employed during polymerization has a profound influence on the stability of the resulting film, and SEM analysis indicate that film morphology plays an important role in this effect. In the absence of oxygen, conductivity loss is significantly slower and displays a strong dependence on chloride content.

Gas Phase Ethylene Polymerization: Production Processes, Polymer Properties, and Reactor Modeling

Abstract: A review of relevant macroscopic and microscopic processes of gas phase ethylene polymerization, both chemical and physical, is given. The commercial technology development of gas-phase ethylene polymerization processes is illustrated through a selective survey of the patent literature. Both advantages and disadvantages of gas phase polymerization processes are addressed, and the challenges of laboratory studies of gas phase polymerization are also outlined. Physicochemical phenomena of ethylene polymerization using heterogeneous catalysts are discussed, including examination of catalyst preparation, polymer morphological development, and elementary chemical reactions. Metallocene-based catalysts and their kinetic performance for olefin polymerizations are also discussed

Biofunctional surface modified ocular implants, surgical instruments, medical devices, prostheses, contact lenses and the like

Abstract: A method for modifying the surface of a material adapted for contact with tissue of a human or non-human animal to impart biofunctional, bioactive or biomimetic properties to the surface comprising: (a) exposing the surface to a solution comprising (1) an ethylenically unsaturated monomer or mixture thereof capable, via the ethylenic unsaturation, of gamma irradiation or electron beam induced polymerization, and (2) at least one biofunctional agent; and (b) irradiating the surface with gamma or electron beam irradiation in the presence of the solution to thereby form on the surface a graft polymerized coating, the coating having physically entrapped therein or chemically bonded thereto molecules of the at least one biofunctional agent which imparts biofunctional or biomimetic properties to the surface; wherein the gamma or electron beam irradiation induced polymerization is conducted under one of the following conditions: A. (i) monomer concentration in the solution in the range of from about 0.1% to about 50%, by weight; (ii) total gamma or electron beam dose in the range of from about 0.001 to less than about 0.50 Mrad; and (iii) gamma dose rate in the range of from about 10 to about 2,500 rads/min., or electron beam dose rate in the range of from about 10 to about 10 8 rads/min.; B. (i) hydrophilic monomer(s) graft under conditions which may include monomer pre-soak or plasma gamma surface modification (especially for metal or glass substrates in latter case); and (ii) graft polymerization of monomer(s) with bioactive/biofunctional molecules using (i) as substrate; C. (i) Hydrograft™ as in A or B above followed by dehydration and adsorption of bioactive/biofunctional molecules into the hydrophilic polymer graft; wherein the biological properties of the biofunctional agent are substantially maintained.

Superabsorbent polymer having improved absorption rate and absorption under pressure

Abstract: A superabsorbent polymer having improved absorption under pressure and fast absorption rate is obtained by first providing a solution containing carboxylic acid monomers or water soluble salts thereof, and a crosslinking agent. A carbonate blowing agent and a polymerization initiator are added, individually or in combination, to the solution to form a carbonated monomer solution. A polymerization initiator is then added to the carbonated monomer solution which is then polymerized at temperatures ranging from about 0° C. to about 130° C., forming a microcellular hydrogel. The microcellular hydrogel is chopped or ground into gel pieces having a particle diameter ranging from about 0.1 mm to about 5.0 cm. The gel pieces are dried at temperatures ranging from about 85° C. to about 210° C., and are then ground to form a polymer having a particle size of from about 0.05 mm to about 5.0 mm. A mixture is formed from 100 parts by weight of the polymer and about 0.001 to about 30 parts by weight of a surface crosslinking agent. The polymer is reacted with the surface crosslinking agent to crosslink molecular chains existing on a surface of the polymer, forming the superabsorbent polymer.

'Living' Radical Polymerization. 1. Possibilities and Limitations

Abstract: : Possibility of the synthesis of well-defined polymers by radical polymerization is discussed. Kinetic analysis demonstrates that the preparation of polymers with controlled macromolecular structure in a 'living' radical process requires low stationary concentration of growing radicals which are in a dynamic equilibrium with dormant species. Three approaches are described. First, when growing radicals react reversibly with scavenging radicals to form covalent species, second when growing radicals react reversibly with covalent species to produce persistent radicals and the third in which growing radicals participate in the degenerative transfer reaction which regenerates the same type of radicals. Some of the reported 'living' radical systems are critically evaluated.

Regioselective polymerization of 3-(4-octylphenyl)thiophene with FeCl3

Abstract: We have shown that it is possible to regioselectively polymerize 3-(4-octylphenyl) thiophene with FeCl3. Adding FeCl3 slowly to the monomer leads to a soft and therefore regioselective polymerizati ...

Dispersion polymerization of methyl methacrylate: Mechanism of particle formation

Abstract: The mechanism for the formation of micron-size polymer particles in the dispersion polymerization of methyl methacrylate was investigated by applying dynamic light scattering to monitor the evolution of the average particle size in the early stages of the polymerization. In addition, the contributions of physically adsorbed stabilizer and graft copolymer were evaluated by measuring the bound, unbound (adsorbed), and free stabilizer, and by determining the amount of added stabilizer required in seeded dispersion polymerizations. Twenty nanometer particles (termed nuclei) were the smallest particles detected and are considered to be formed by aggregation of growing polymer chains precipitating from solution as they exceed their critical chain length. Aggregation of these nuclei with themselves and their aggregates continues until mature and stable particles are formed. This occurs when sufficient stabilizer occupies the particle surface which includes both the polymeric stabilizer [poly(vinylpyrrolidone)] and its graft copolymer which is created in situ. The effects of process variables are discussed based on this mechanistic picture of the dispersion polymerization process. © 1994 John Wiley & Sons, Inc.

IR spectra and structure of V2O5GeO2Bi2O3 glasses

Abstract: This paper reports a study of the structure V2O5GeO2Bi2O3 glasses by IR spectroscopy to obtain information about the competitive role of each of V2O5, GeO2 and Bi2O3 in the formation of the glass network. The amorphous samples were obtained by the twin-roller technique. Bi2O3 leads to transformation of the layered and chain vanadate structure and depolymerization of three-dimensional germanate lattice. The bismuthate complexes can be viewed as deformed BiO6 groups. It is established that with a decrease in the V2O5 content VO4 groups are formed. GeO4 structural unit with different degrees of polymerization arer present in the network in the entire concentration range.

Living Cyclopolymerization of 1,6-Heptadiyne Derivatives Using Well-Defined Alkylidene Complexes: Polymerization Mechanism, Polymer Structure, and Polymer Properties

Abstract: We report here the living cyclopolymerization of 1,6-heptadiyne derivatives (usually 4,4-disubstituted) using well-defined alkylidene complexes as initiators. Diethyl dipropargylmalonate (2a), di-tert-butyl dipropargylmalonate (2b), optically active di-(1R,2S,5R)-([minus])-menthyl dipropargylmalonate (2c([minus])), di-(1S,2R,5S)-(+)-menthyl dipropargylmalonate (2c(+)), di-(1R)-endo-(+)-fenchyl dipropargylmalonate (2d), 4,4-bis[[(p-tolylsulfonyl) oxy]methyl]-1,6-heptadiyne (3b), 4,4-bis[(trimethylsiloxy)methyl]-1,6-heptadiyne (3c), the cyclic silyl ether, PhEtSi(OCH[sub 2])[sub 2]C-(CH[sub 2]C[triple bond]CH)[sub 2] (3d), and N,N-dipropargyl-2,4,6-triisopropylbenzamide (5b) are polymerized to give soluble polymers in high yield using Mo(NAr)(CHCMe[sub 2]Ph)(OR[sub F6])[sub 2] (1a; Ar = 2,6-i-Pr[sub 2]C[sub 6]H[sub 3], OR[sub F6] = OCMe(CF[sub 3])[sub 2]) as the initiator in 1,2-dimethoxyethane (DME). The polymers show a high degree of conjugation ([lambda][sub max] > 500 nm) and have narrow molecular weight distributions. Poly(2a) is soluble in most organic solvents (THF, C[sub 6]H[sub 6], toluene, CH[sub 2]Cl[sub 2], CHCl[sub 3], DME, DMF, MeCN). The mechanism of the polymerization has been investigated by [sup 1]H NMR studies and by monomer, initiator, and solvent variations. Symmetric, diphenyl-capped polyenes, [open quotes]pull-pull[close quotes] polyenes containing p-cyanophenyl end groups, and [open quotes]push-push[close quotes] polyenes containing p-dimethylamino end groups have all been prepared. 93 refs., 12 figs., 11 tabs.

Narrow Polydispersity Polystyrene by a Free-Radical Polymerization Process-Rate Enhancement

Abstract: It is shown that the rate of polymerization of nitrixide-mediated stable free radical polymerization processes for styrene-based polymers and copolymers can be dramatically increased by the addition of camphorsulphonic acid (CSA). Very narrow polydispersity resins are obtained with CSA concentrations of 0.02 M or less, while larger amounts of CSA result in slight increases in polydispersity

Heat-induced conformational changes in whey protein isolate and its relation to foaming properties

Abstract: Heat-induced changes in the physicochemical properties of whey protein isolate (WPI) have been studied. WPI (5%) heated at 70 o C underwent rapid conformational changes within 1 min. The aperiodic structure content increased primarily at the cost of β-sheet structure. The hydrophobic character, as measured by changes in the pH-solubility profile and the solubility profile at pH 4.6 in NaCl solutions, of the protein surface increased. However, the surface hydrophobicity, as measured by the cis-parinaric acid binding method, decreased. In contrast, WPI (9%) heated at 90 o C did not exhibit significant changes in the secondary structure content