Gel Permeation Chromotography Research Articles

Influence of molecular weight on the short-channel effect in polymer-based field-effect transistors

In this study, we demonstrate how the intrinsic properties of a polymer can influence the electrical characteristics of organic field-effect transistors (OFETs). OFETs fabricated with three batches of poly[2-methoxy,5-(3′,7′-dimethyl-octyloxy)]-p-phenylene vinylene (MDMO-PPV) were investigated. The properties of the polymers were initially investigated using Fourier transform infrared spectroscopy (FTIR), impedance spectroscopy (IS), gel permeation chromotography (GPC), and cyclic voltammetry (CV), respectively. The structure and purity of the polymer batches were found to be very comparable, but the molecular weight (Mn and Mw) and polydispersity (PDI = Mw/Mn), varied between the samples and the HOMO and LUMO levels of the polymers were found to depend on the molecular weight properties. OFETs were then fabricated with the polymers and electrically characterized. It was observed that the channel current and the field-effect mobility increase with increasing polymer molecular weight. The output characteristics of the transistors, on the other hand, were found to depend on the PDI of the polymer. Saturation of the channel current occurs at higher source–drain voltages and short-channel behavior was observed to start at longer channel lengths for polymers with a higher PDI. This behavior is observed to be thickness dependent, and the short-channel behavior was more pronounced for thicker MDMO-PPV films. These results are explained in terms of influences of chain packing and ordering and high bulk currents on the FET output and transistor parameters. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 50: 117–124, 2012

Synthesis of block copolymers consisting of poly(3-hexylthiophene) and polystyrene segments through ionic interaction and their self-assembly behavior

A series of well-defined aniline-chain-end-functionalized regioregular poly(3-hexylthiophene)s (P3HT-NH2) have been successfully synthesized on the basis of Grignard metathesis polymerization. The molecular weights of P3HT-NH2 could be varied from 1960 to 28 000 g mol−1, with low polydispersity indices in the range of 1.06–1.29, as determined by gel permeation chromotography. The selectivity of monofunctionalization reactions and the high degrees of amine functionality (85–92%) were confirmed by Matrix-assisted laser desorption ionization time-of-flight mass spectroscopy. Block copolymers through ionic interaction were successfully synthesized by simply blending P3HT-NH2 with carboxy chain-end-functionalized polystyrene, which was prepared on the basis of living anionic polymerization. The thermal and optical properties of block copolymers were investigated by differential scanning calorimetry, Thermogravimetric analysis and UV-vis spectroscopy. The self-assembly behavior of the polymer was investigated by atomic force microscopy and grazing incidence X-ray scattering. Well-defined aniline-chain-end-functionalized regioregular poly(3–hexylthiophene)s (P3HT-NH2) have been synthesized on the basis of Grignard metathesis polymerization. The selectivity of monofunctionalization and the high degree of amine functionality (85–92%) were confirmed by MALDI-TOF mass spectroscopy. A block copolymer through ionic interaction was successfully synthesized simply by blending P3HT-NH2 with carboxy chain-end-functionalized polystyrene. Thermal and optical properties of the block copolymer are investigated by DSC, TGA and UV-vis spectroscopy. The self-assembly behavior of the polymer was observed by AFM showing nanofibril structures with 12–15 nm width.

Controllable synthesis and micelles preparation of tri-block copolymers from 2,2-dimethyl-trimethylene carbonate and ethylene glycol

Amphiphilic triblock copolymer of poly(2,2-dimethyl-trimethylene carbonate)–poly(ethylene glycol)–poly(2,2-dimethyl trimethylene carbonate) (PDTC–PEG–PDTC) was synthesized by dihydroxyl capped PEG with molecular weight of 1,000, 4,000, and 6,000 in the presence of rare earth tris(2,6-di-tert-butyl-4-methylphenolate)s. The rare earth phenolates/PEG system could prepare triblock copolymer with predictable molecular weights with narrow molecular weight distribution. The polymers were characterized by nuclear magnetic resonance spectroscopy, gel permeation chromotography, and differential scanning calorimetry to confirm the structure. The micelles formed from the amphiphilic triblock copolymer were determined by fluorescence spectrophotometer and dynamic light scattering. The critical micelle concentrations fell in the range of 1.67∼5.25 mg/L. Transmission electron microscopy pictures showed that the micelles possess spherical morphology, and the diameters of micelles in number averaged scale ranged from 20–70 nm. The micelles formed from triblock amphiphilic copolymers were explored as carrier for indomethacin (IND), and they could enhance IND solubility in water dramatically.

Cationic Ring Opening Polymerization of Octamethylcyclotetrasiloxane Initiated by Acid Treated Bentonite

Cationic ring opening polymerization of octamethylcyclotetrasiloxane (D 4) initiated by acid treated bentonite was investigated. The experimental conditions were chosen on the basis of preliminary experiments. Higher temperature was found beneficial for the reaction process while stirring intensity beyond a certain level showed no obvious effect on the reaction rate. Polymers were characterized by Fourier transform infrared, proton nuclear magnetic resonance ( 1H-NMR) and gel permeation chromotography. The width of molecular mass distribution was found ranging between 1.2 and 1.4, which is extraordinarily narrow compared with that of cationic polymerizations reported elsewhere (>1.9). The results were believed due to the absence of free proton and counter ion which simplifies the polymerization process and the huge steric hindrance provided by bentonite particles which keeps the propagation of polysiloxane onto the surface of bentonite particles in a much more regular way. A feasible mechanism is proposed and seems to be supported well by experiments. Additionally, from the results of α, ω-dihydrogen terminated polysiloxanes prepared, the possibility of applying this potential environmentally friendly heterogeneous catalyst in industrial polymerization of cyclosiloxanes is anticipated.

Composites of carbon black functionalized with polymers as candidates for the detection of methanol vapor

Homo- and copolymers of styrene and 4-vinylpyridine prepared by a nitroxide-mediated “living” free-radical method were grafted onto carbon black (CB) by trapping of radicals formed by the dissociation of the radical-capped polymers. The structural characteristics of the polymers and the composites were investigated by using Fourier transformed infrared spectra, nuclear magnetic resonance spectra, thermal gravimetric analysis, scanning electron microscopy and gel permeation chromotography. The composites were dip-coated on interdigitated electrodes to prepare thin film gas sensors, and their electrical responses towards methanol vapor were investigated at room temperature. It was found that the composites exhibited linear and reversible electrical responses towards methanol vapor in the range of 1000–20,000 ppm ( R 2 = 0.999), and the sensitivities are highly dependent on the structure of the polymers, the content of CB and the dispersion of CB in the composites.

Time-Resolved EPR Studies of Main Chain Radicals from Acrylic Polymers. Structural Characterization at High Temperatures

Main chain radicals from several acrylic polymers are characterized in liquid solution at high temperatures (∼100 °C) using time-resolved electron paramagnetic resonance (TREPR) spectroscopy. The radicals are produced by laser flash photolysis (248 nm) and subsequent loss of the side chain ester functionality by Norrish I α-cleavage. At these temperatures fast-motion spectra with conformationally averaged hyperfine interactions are observed. The spectra are strongly spin polarized from the triplet mechanism (TM) of chemically induced dynamic electron spin polarization (CIDEP). Computer simulation of the TREPR spectra leads to unambiguous structural characterization of both the main chain radical and the side chain oxo-acyl radical. Hyperfine coupling constants, g-factors, and line widths are reported and discussed for radicals produced from five different acrylic polymers. Variation of the side chain on the polymer backbone leads to significant changes in the observed hyperfine coupling constants. For the main chain radical from poly(fluorooctyl methacrylate) (PFOMA), fast motion of the polymer chain is not accessible at these temperatures. The side chain oxo-acyl radical from PFOMA exhibits long-range 19F hyperfine interactions. Additional TREPR experiments on small molecule model compounds and gel permeation chromotography results of the photolyzed polymers support the conclusion that the primary photodegradation mechanism proposed in this paper is general for acrylic polymers.

Gas-phase polymerization of ethylene using supported metallocene catalysts: Study of polymerization conditions

The influence of polymerisation conditions on the gas-phase polymerization of ethylene with a supported metallocene catalyst (Cp 2 ZrCl 2 /SiO 2 ) was investigated. The experiments were carried out in 1.0-L semi-batch autoclave reactor and in 0.6-L glass reactor, at pressures up to 100 psi and temperatures up to 57°C. Anchor and helicoidal agitators were used. Trimethylaluminium (TMA) and methylalyminoxane (MAO) were used as cocatalysts. Hydrogen was used as the chain-transfer agent. The polymer products were characterized by gel permeation chromotography (GPC) and scanning electron microscopy (SEM). Effects of pre-contact time of the catalyst and cocatalyst, catalyst injection con-figuration, agitator design, hydrogen volyme, polymerization temperature and pressure were studied. The heterogeneity of polymer particles inside different zones of the reactor was also verified. The results indicated that several of these factors were crucial to obtain well-controlled gas-phase polymerization. SEM analyses showed that irregular growth of polymer within the shells often formed polymer particles of irregular shape. Flory's distribution was used to describe the polymerization mechanism for each site type. Interactions between catalyst sites and support surface are considered to broaden these distributions. Several Flory's distributions (4 to 7 different site types) were required to describe the broad and sometimes multimodal molecular weight distributions.

Synthesis and NMR characterization of 6‐Phenyl‐6‐deoxy‐2,3‐di‐O‐methylcellulose

AbstractCellulose (1) was converted for the first time to 6‐phenyl‐6‐deoxy‐2,3‐di‐O‐methylcellulose (6) in 33% overall yield. Intermediates in the five‐step conversion of 1 to­6 were: 6‐O‐tritylcellulose (2), 6‐O‐trityl‐2,3‐di‐O‐methylcellulose (3), 2,3‐di‐O‐methylcellulose (4); and 6‐bromo‐6‐deoxy‐2,3‐di‐O‐methylcellulose (5). Elemental and quantitative carbon‐13 analyses were concurrently used to verify and confirm the degrees of substitution in each new polymer. Gel permeation chromotography (GPC) data were generated to monitor the changes in molecular weight (DPw) as the synthesis progressed, and the compound average decrease in cellulose DPw was ∼ 27%. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to characterize the decomposition of all polymers. The degradation temperatures ( °C) and percent char at 500 °C of cellulose derivatives 2 to 6 were 308.6 and 6.3%, 227.6 °C and 9.7%, 273.9 °C and 30.2%, 200.4 °C and 25.6%, and 207.2 °C and 27.0%, respectively. The glass transition temperature (Tg) of­6‐O‐tritylcellulose by dynamic mechanical analysis (DMA) occurred at 126.7 °C and the modulus (E′, Pa) dropped 8.9 fold in the transition from −150 °C to + 180 °C (6.6 × 109 to 7.4 × 108 Pa). Modulus at 20 °C was 3.26 × 109 Pa. Complete proton and carbon‐13 chemical shift assignments of the repeating unit of the title polymer were made by a combination of the HMQC and COSY NMR methods. Ultimate non‐destructive proof of carbon–carbon bond formation at C6 of the anhydroglucose moiety was established by generating correlations between resonances of CH26 (anhydroglucose) and C1′, H2′, and H6′ of the attached aryl ring using the heteronuclear multiple‐bond correlation (HMBC) method. In this study, we achieved three major objectives: (a) new methodologies for the chemical modification of cellulose were developed; (b) new cellulose derivatives were designed, prepared and characterized; (c) unequivocal structural proof for carbon–carbon bond formation with cellulose was derived non‐destructively by use of one‐ and two‐dimensional NMR methods. Copyright © 2002 John Wiley & Sons, Ltd.

Photopolymer: synthesis and characterization of poly(4-methacryloyloxyphenyl-4?-chlorostyryl ketone)

Methacrylate monomer containing a photodimerizable α,β-unsaturated ketone moiety was prepared and polymerized in ethyl methyl ketone at 70 °C using benzoyl peroxide as an initiator. The polymer was characterized by UV, IR, 1H NMR and 13C NMR spectra. The molecular weights (Mw and Mn) of the polymer were determined by gel permeation chromotography. The thermal stability of the polymer was measured by thermogravimetric analysis in air and nitrogen. The glass transition temperature of the polymer was determined by differential scanning calorimetry. The photo reactivity of the polymer was investigated as thin film and in solution. © 2000 Society of Chemical Industry

Characterization of low molecular weight poly(β-hydroxybutyrate)s from alkaline and acid hydrolysis

In the present paper, low molecular weight poly(β-hydroxybutyrates) (PHBs), which were obtained by acidic and basic hydrolysis of bacterially produced PHB, were characterized by gel permeation chromotography (GPC), 1H, 13C and 31P NMR. The assignments of the resonances of 13C NMR spectra from unsaturated end and hydroxy end groups were made using heteronuclear multiple quantum coherence (HMQC) NMR technique. Unsaturation contents and number average molecular weights of the PHBs were determined mainly by 1H and 31P NMR. Direct measurement of the molecular weights of PHB has also been carried out by matrix assisted laser desorption ionization (MALDI). Based on the characterization of these low molecular weight PHBs, the heterogeneous hydrolysis mechanism is discussed and the scission of PHB chains is proposed to occur at the surfaces and interfaces of lamellar crystals. The unsaturated end group is formed by dehydration of the chain ends by β-elimination after ester hydrolysis, which is different from the mechanistic steps of the formation of unsaturated ends in thermal decomposition of PHB. The correlation of thickness of crystal lamellae and the melting points has also been discussed. The plot of the melting point against reciprocal lamellar thickness for low molecular weight PHB indicates the pronounced effect of the surface energy of these crystals, which is caused by the large proportion of end groups.

Electropolymerization of trimethylsilylphenols to silylated polyphenylene oxides and investigation of their properties. Enhanced conductivity of PPO by silyl group

Polymerization of o-, m-, and p-trimethylsilylphenols (TMS-phenols) was achieved electrochemically. The polymers were prepared as thin films on a platinum electrode and were found to be electroinactive in nonaqueous solutions. The polymers exhibited far higher conductivities than polyphenol or other substituted polyphenols. The conductivity of poly(p-TMS-phenol) was lower than that observed for the polymers of the o- and m-isomers. The polymers were characterized by infrared spectroscopy. The effect of monomer concentration, supporting electrolyte concentration, current densities, and temperature on the polymerization was investigated using microgravimetry. The observed empirical kinetics were as follows. The rates of polymerization of o-,m-, and p-TMS-phenol were found to be of 0.8, 0.8, and 0.7 order dependent on monomer concentation, of 0.5, 0.5 and 0.45 order dependent on electrolyte concentration, and of 0.9, 0.9 and 0.8 order dependent on current densities. By investigating the effect of temperature on electropolymerization, the corresponding activation energies of electropolymerization were calculated to be 0.9, 0.9, and 0.8 kJ/mole. The molecular weights of poly(o-TMS-phenol) and poly(m-TMS-phenol) were determined by gel permeation chromotography. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1121–1126, 1997

Analysis of pheromone binding and pheromone reception by Enterococcus faecalis.

Bacteriocin plasmid pPD1 in Enterococcus faecalis encodes a mating response to a small-peptide sex pheromone, cPD1, secreted from recipient cells5. To investigate how a pPD1-harboring donor cell receives the pheromone signal, a tritiated pheromone, [3H]cPD1, was synthesized which was fully active during bioassay. Initially, [3H]cPD1 was incubated with donor cells harboring pAM351 (=pPD1: Tn916) or plasmid-free recipient cells and then the radioactivities of the cells were measured. The activity of the donor cells was about five times higher than that of the recipient cells (Table 1). This result suggests that the donor cells bind or uptake pheromone. The radioactivity of the donor cells reached a maximum in 20 to 30 minutes at both 4°C and 37°C. Lysozyme-treated cells, spheroplasts, harboring pAM351, showed a pheromone-binding activity higher than the intact cells did (Table 1). This indicates that the cell wall is an obstacle for the pheromone to approach the cell membrane. Membranes of donor cells showed no detectable binding activity specific to cPD1 (data not shown). On the other hand, cell-free extract showed high binding activity (Table 1). These results suggest that the pheromone is internalized into cells and bound to some component existing in the cytosol. Furthermore, the binding component was found to have a molecular weight as high as 30,000 Da based on gel permeation chromotography. Scatchard analysis with the donor spheroplast displayed an apparent Kd of 0.45 nM and approximately a hundred binding sites per cell.KeywordsDonor CellEnterococcus FaecalisRecipient CellPlasmid TransferPheromone ReceptorThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Synthesis, characterization, and thermodynamic analysis of a 1 + 1 self-assembling structure based on the cyanuric acid.cntdot.melamine lattice

This article describes the reaction of the trivalent melamine derivative C 6 H 3 -1,3,5-[CO 2 (CH 2 ) 4 OCOC 6 H 4 -2-NH- C 3 N 3 (NH 2 )(NHCH 2 CH 2 C(CH 3 ) 3 )] 3 (homoflexM 3 , h-flexM 3 ) with the trivalent isocyanurate derivative C 6 H 3 -1,3,5-[CONHC 6 H 4 -3-N((CH 2 ) 17 CH 3 )COC 6 H 3 -2-NC(O)NHC(O)NHC(O)-5-O(CH 2 ) 17 CH 3 ] 3 (hubCA 3 ) in CHCl 3 to afford a structurally well-defined 1+1 supramolecular aggregate h-flexM 3 .hubCA 3 .This structure is held together by a network of 18 hydrogen bonds and is one of the most stable nonbiological supramolecular aggregates synthesized to date.The structure was characterized by 1 H NMR and UV spectroscopies, gel permeation chromotography ,and vapor pressure osmometry.The exchange reaction between h-flexM 3 .hubCA 3 and h-flexM' 3 (a close structural analog of h-flexM 3 ) was monitored by 1 H NMR spectroscopy.This exchange reaction appeared to occur by dissociation; the reaction was first-order in h-flexM 3 .hubCA 3 and zero-order in h-flexM' 3 .The transition-state parameters for the axchange reaction were calculated by following the exchange process at several temperatures.

Molecular weight distribution of chitosan isolated from Mucor rouxii under different culture and processing conditions

The isolation of chitosan from a fungal source offers the potential of a product with controlled physicochemical properties not obtainable by the commercial chemical conversion of crustacean chitin. A variety of culture and processing protocols using Mucor rouxii were studied for their effects on biomass yield and chitosan molecular weight. Weight-averaged molecular weight determined by gel permeation chromotography ranged from 2.0 x 10(5) to approximately 1.4 x 10(6) daltons. The chitosan yield ranged from 5% to 10% of total biomass dry weight and from 30% to 40% of the cell wall. Of the culture parameters studied, length of incubation and medium composition effected biomass production and molecular weight. Modification of the processing protocol, including the type and strength of acid, and cell wall disruption in acid prior to refluxing were used to optimize the efficiency of chitosan extraction.The degree of deacetylation of fungal and commercial chitosans was compared using infrared spectrometry, titration, and first derivative of UV absorbance spectrometry. The chitosan obtained directly from the fungal cell wall had a higher degree of deacetylation than commercial chitosan from the chemical conversion process.

Molecular degradation of polymers

AbstractAn understanding of the transmittal of force or stress through the molecular (or atomic) network of a body should not only be helpful in predicting the load carrying capability of materials but might also provide information on how structure can be altered to enhance properties. A molecular understanding of mechanical properties is particularly difficult in polymers where such factors as molecular weight, tacticity, crystallinity, presence of networks, orientation, etc., may have an influence. In no class of materials are intricacies of physical structure more important than in polymers. Polymers with very similar chemical structures but differing physical structure can have physical properties differing by orders of magnitude. It would obviously be helpful to have means to probe molecular and atomic events and occur during the loading and destruction of the polymer structure. Instruments that have been used for this purpose include: (1) electron spin resonance (ESR) to monitor free radical production resulting from homolytic chain scission, (2) Fourier transform infrared spectroscopy (FTIR) to measure new end groups resulting from molecular chain rupture, and (3) intrinsic viscosity or gel permeation chromotography (GPC) to detect molecular weight changes (MWC) accompanying molecular degradation. This presentation will discuss and compare research results from these methods. Particular emphasis will be placed on recent studies in which computer modeling has been used to identify ESR spectra and a comparison of the results obtained by ESR, FTIR, and MWC for polystyrene.

Adsorption of monodisperse polystyrene onto porous glass: II. Study of the exchangeability of adsorbed polymer layer

Exchangeability in the adsorption layer of one polymer by another was analyzed for different molecular weight combinations of polystyrene using gel permeation chromotography. The adsorption layers formed by small molecules are exchanged effectively by the solution of large molecules and the degree of exchange is dependent on the difference in their molecular weights. Furthermore, the degree of exchange extensively influences the solution concentration at which the corresponding adsorption is carried out, i.e., the polymer layer formed at the higher concentration is exchanged more easily than the layers at lower concentrations. This can be explained as follows: the polymer molecules in the dilute solution arrive at the sparsely populated surface, adopting a flat conformation, but the polymer molecules in the concentrated solution, especially when later arrivals come to the surface, occupy a smaller number of sites and make an extended loop conformation, which is exchanged more easily than are molecules in a flat conformation.

Chemical structure of heavy oil from coal hydrogenation 1. Hydrogenation with zinc chloride catalyst

Oil product from the hydrogenolysis of a high-volatile bituminous coal was separated by solubility, fractionated by gel permeation chromotography and characterized by structural analysis. The average structural unit in the hexane-soluble, aromatic oil fraction consists of 1–3 aromatic rings with 0.3-0.5 of the ring carbons substituted by alkyl groups and oxygen containing groups. Molecular weights vary from 200 to 500. The larger molecular weight fractions have longer alkyl chains and lower carbon aromaticities. The molecules are mainly of single unit structures. The average structural units in asphaltene fractions contain from 2.5-4 aromatic rings, are of higher carbon aromaticities and contain shorter alkyl groups. The asphaltene molecules consist of two or more structural units, crosslinked together, and have molecular weights of 300–1400. The oxygen content of the fractions decreases with decreasing molecular weight. Increasing the amount of ZnCl 2 catalyst during hydrogenolysis resylts in an increased yield of lower-molecular-weight material, but no change in the structural properties of the product. This is interpreted to mean that ZnCl 2 is active in the scission of covalent bonds between structural units during liquefaction and that the hydrogenolysis reaction is mostly cleavage of crosslinks between structural units with minimal reaction of the units themselves.

Reactions of poly(phenylene oxide)s with quinones. I. The quinone‐coupling reaction between low‐molecular‐weight poly(2,6‐dimethyl‐1,4‐phenylene oxide) and 3,3′,5,5′‐tetramethyl‐4,4′‐diphenoquinone

AbstractA bifunctional polymer is formed when low‐molecular‐weight poly(2,6‐dimethyl‐1,4‐phenylene oxide) (I) reacts with 3,3′,5,5′‐tetramethyl‐4,4′‐diphenoquinone (II). Infrared (IR), nuclear magnetic resonance (NMR), and gel permeation chromotography (GPC) measurements indicate that the quinone is bound covalently to the polymer chain as a biphenyl moiety which can be located at a terminal position (III, a = 0) or an internal position (III, a > 0): magnified image Acetylation of III produces a diacetate ester characterized by field desorption mass spectrometry to confirm the bifunctional nature of III. The reaction of I with II proceeds at 25°C but is faster at elevated temperatures or with amine catalysis. Oxidation of III with oxygen and a copper/amine catalyst of the type used initially to prepare I regenerates II from the biphenyl moiety in III in high yield and converts the remaining oxyphenylene units to high‐molecular‐weight polymer.

Solid State Photochemistry of Polycarbonates

The quantum yield of photoFries rearrangement in a polycarbonate film has been analyzed as a function of temperature and humidity on the basis of previously reported (Koyler and Mann, 1977) experimental data. Results indicate that in the homogeneous amorphous phase, photoFries rearrangement is a concerted process proceeding either from the pi star reversed arrow n singlet, in which case it must be subject to considerable self quenching, or from a triplet, presumably the first triplet since the lifetime of higher triplets is expected to be very short in the solid phase. If the parent excited state is the first triplet, chain scission is possibly an independent process, probably occurring from the pi star reversed arrow n singlet. Evidence of chain scission on photodegradation in the solid state includes loss of C-O and C-C bond intensities revealed in the Fourier transform infrared spectra, gel permeation chromotography elution profiles of degraded film samples dissolved in CHCl3, and a decrease in tensile strength and T sub g as photodegradation proceeds. Chain scission is apparently inhibited as photoFries products accumulate.

Bovine transfer factor: Effect on bovine and rabbit coccidiosis

Bovine transfer factor (TF) was produced from lymph node lymphocytes of calves that showed delayed hypersensitivity (DH) to Eimeria bovis, diphtheria toxoid, and purified protein derivative (PPD) by incubation of lymphocyte suspensions in balanced salt solutions. This procedure produced relatively large amounts of TF and enabled us to conduct several investigations with a given TF preparation. Calves responded to passive transfer of TF with a typical DH reaction as determined by skin testing and histopathological examination. Peripheral blood lymphocytes obtained from these calves showed significant stimulation reactions to E. bovis and PPD. Partial immunity to infection with E. bovis, as determined by a reduction in the number of oocysts passed, and death due to bovine coccidiosis were demonstrated after TF treatment of susceptible calves. Rabbits given bovine TF showed a DH response to the cross-reacting E. stiedai. However, this response did not protect them against infection with E. stiedai. TF prepared from E. stiedai-infected and skin-test-positive rabbits also transferred DH to the homologous antigen, but failed to protect them against E. stiedai infection. Components active in the transfer of DH skin reactivity were partly purified by gel permeation chromotography. The active TF fraction contained ribose-reacting material, and had a 260 280 ratio of 2 and an estimated molecular weight of 1100.