Donald Patterson

Bio: Donald Patterson is an academic researcher from McGill University. The author has contributed to research in topics: Alkane & Cyclohexane. The author has an hindex of 25, co-authored 78 publications receiving 2310 citations. Previous affiliations of Donald Patterson include Complutense University of Madrid.

Polymer compatibility with and without a solvent

Abstract: A qualitative review of the thermodynamics of polymer systems will be given in terms of three contributions: positional (or combinatorial) entropy, an “international” term and a free volume term. From this one finds that a simple polymer-solvent system phase separates on lowering T to an Upper Critical Solution Temperature (UCST) or raising it to Lower Critical Solution Temperature (LCST), To achieve miscibility of two polymers of high molecular weight, one requires a “specific” interaction, usually a weak charge-transfer complex or a hydrogen bond. Phase separation takes place on raising the temperature to an LCST. These various UCST and LCST are predicted semi-quantitative by the Prigogine-Flory theory. When a solvent is added to two miscible polymers, a new type of phase separation appears since there is an effect of any difference in the strengths of the two polymer-solvent interactions. Phase separation may easily occur in the ternary system where there is none in the three binary systems, and examples will be given. In the case of two highly-attractive polymers in a solvent, a quite different phase separation occurs, sometimes called complex coacervation. A simple Flory-Huggins type theory predicts these phenomena in ternary systems.

Volumes of mixing and theP* effect: Part I. Hexane isomers with normal and branched hexadecane

Abstract: The Prigogine-Flory theory of solution thermodynamics has been used to interpret molar excess volume data, V E , for two series of alkane mixtures: the five isomers of hexane mixed with normal hexadecane (Data from Reeder, et al.) and the five hexane isomers mixed with a highly branched hexadecane isomer, 2,2,4,4,6,8,8-heptamethylnonane (this work). Values of V E are negative and similar for both series, but vary considerably with the hexane within a series. According to the theory, V E contains a ‘P* contribution’ not found in the excess enthalpy and entropy, which depends strongly on the internal pressures and the derived P* parameters of the components. Values of V E are well predicted for both series, the variation of V E corresponding to the different internal pressures or P* parameters of the hexanes.

Thermodynamic effects of orientational order in chain-molecule mixtures. Part 1.—Heats of mixing of globular and normal alkanes

Abstract: Heats of mixing at 25°C have been obtained calorimetrically for alkane mixtures where component 1 is cyclohexane, 2,2-dimethylbutane or n-hexane and component 2 is a normal-Cn, n= 6,8,12 or 16, or a corresponding branched-Cn: 2,2-dimethylbutane, 2,2,4-trimethylpentane, 2,2,4,6,6-penta-methylheptane or 2,2,4,4,6,8,8-heptamethylnonane. For the three n-Cn series, the molar heats and heats per unit volume are positive and increase rapidly with n. With the branched-Cn, cyclohexane gives smaller positive heats decreasing with n, while n-hexane and 2,2-dimethylbutane show increasingly negative heats. The magnitudes and variations of the heats, and of the derived X12 parameters are inconsistent with the usual interpretation of positive ΔHM in n-alkane mixtures, i.e. an energetic weakness of methyl(end)-methylene (middle) interactions. The results are explained by energetic effects associated with a correlation of molecular orientations (CMO) in the pure components and the mixture. The CMO, studied optically by Bothorel and collaborators, is highly sensitive to molecular shape, increasing with n for pure n-Cn liquids, remaining zero for the branched-Cn, and being destroyed on mixing with spherical molecules such as cyclohexane and 2,2-dimethylbutane. Parameters (J), characterizing the CMO in the component liquids, are used to give a quantitative interpretation of the X12 and ΔHM values.

Volumes of mixing and theP* effect: Part II. Mixtures of alkanes with liquids of different internal pressures

Abstract: The Flory theory of solution thermodynamics is used to predict exess volumes for systems containing a series of n-alkanes mixed with liquids of higher P* parameter and internal pressure, i.e., cyclopentane, cyclohexane, carbon tetrachloride, benzene and dioxane as well as of lower P*, i.e., decamethyltetrasiloxane. Trends of V E , e.g. changes of sign with alkane carbon number are well predicted and indicate the importance of the P* contribution in V E . Mixtures of hexane isomers with liquids of much higher P* typically have large excess enthalpies through zero as an S-shaped curve against composition which is negative on the side of the high P* component. This behaviour is interpreted as arising from increasingly large negative P* contributions in V E .

Structure and the thermodynamics of non-electrolyte mixtures

Abstract: A review is given of thermodynamic effects arising from the following types of order in liquid components or their mixtures: quadrupolar order in benzene as shown by the benzene-cyclohexane system, orientational order in long-chain normal alkanes revealed by their mixtures with globular molecules, non-randomness in mixtures approaching phase separation, alcohol multimers in inert solvents, water-structuring around hydrophobic solutes, and micelles.

Arsenate and Chromate Retention Mechanisms on Goethite. 1. Surface Structure

Abstract: The molecular structure of ions retained on mineral surfaces is needed to accurately model their sorption process and to determine their stability. Extended X-ray absorption fine structure (EXAFS) spectroscopy was used in this study to deduce the local coordination environment of two environmental contaminants, arsenate and chromate, on the mineral goethite (α-FeOOH). Based on the oxyanion−Fe distances, it was concluded that three different surface complexes exist on goethite for both oxyanions: a monodentate complex, a bidentate-binuclear complex, and a bidentate-mononuclear complex. At low surface coverages, the monodentate complex was favored while at higher coverages the bidentate complexes were more prevalentthe bidentate-binuclear complex appears to be in the greatest proportion at these highest surface coverages. Therefore, modeling efforts for chromate or arsenate retention on goethite need to consider a monodentate complex at very low coverages, both the monodentate and bidentate complexes at in...

Structure and Technofunctional Properties of Protein-Polysaccharide Complexes: A Review

Abstract: Food proteins and polysaccharides are the two key structural entities in food materials. Generally, interactions between proteins and polysaccharides in aqueous media can lead to one- or two-phase systems, the latter being generally observed. In some cases of protein-polysaccharide net attraction, mainly mediated through electrostatic interactions, complex coac-ervation or associative phase separation occurs, giving rise to the formation of protein-polysac-charide complexes. Physicochemical factors such as pH, ionic strength, ratio of protein to polysaccharide, polysaccharide and protein charge, and molecular weight affect the formation and stability of such complexes. Additionally, the temperature and mechanical factors (pressure, shearing rate, and time) have an influence on phase separation and time stability of the system. The protein-polysacchaide complexes exhibit better functional properties than that of the proteins and polysaccharides alone. This improvement could be attributed to the simultaneou...

Supercooled dynamics of glass-forming liquids and polymers under hydrostatic pressure

Abstract: An intriguing problem in condensed matter physics is understanding the glass transition, in particular the dynamics in the equilibrium liquid close to vitrification Recent advances have been made by using hydrostatic pressure as an experimental variable These results are reviewed, with an emphasis in the insight provided into the mechanisms underlying the relaxation properties of glass-forming liquids and polymers

Short Fundamental Equations of State for 20 Industrial Fluids

Abstract: In a preceding project, functional forms for “short” Helmholtz energy equations of state for typical nonpolar and weakly polar fluids and for typical polar fluids were developed using simultaneous optimization. In this work, the coefficients of these short forms for the equations of state have been fitted for the fluids acetone, carbon monoxide, carbonyl sulfide, decane, hydrogen sulfide, 2-methylbutane (isopentane), 2,2-dimethylpropane (neopentane), 2-methylpentane (isohexane), krypton, nitrous oxide, nonane, sulfur dioxide, toluene, xenon, hexafluoroethane (R-116), 1,1-dichloro-1-fluoroethane (R-141b), 1-chloro-1,1-difluoroethane (R-142b), octafluoropropane (R-218), 1,1,1,3,3-pentafluoropropane (R-245fa), and fluoromethane (R-41). The 12 coefficients of the equations of state were fitted to substance specific data sets. The results show that simultaneously optimized functional forms can be applied to other fluids out of the same class of fluids for which they were optimized without significant loss of a...