W. Alexander Van Hook, Physical Chemistry

W. Alexander Van Hook, Physical Chemistry
Paul and Wilma Ziegler Professor
309 Buehler Hall, (865) 974-5105 EMAIL: VANHOOK@NOVELL.CHEM.UTK.EDU

"This research group is interested in exploring the effects of intermolecular forces on the properties of liquids and solutions. We are investigating the effects of pressure, isotopic substitution, chain length, and chain length distribution on excess thermodynamic properties and immiscibility in polymer/solvent and polymer/polymer solutions. The phase transitions are detected by a light scattering technique at elevated temperatures and pressures; the data is interpreted with an approach which combines the statistical theory of condensed phase isotope effects with a modern mean field description of polymer solutions. It takes full account of polydispersity. An understanding of the molecular origins of excess effects and demixing polymer solutions is of great interest because they determine or profoundly influence solubilities, mechanical strength, optical properties, etc., of commercially important materials.

A second area of active research involves high precision measurements of isotope effects on polarizability by differential refractometry. An automated flow system developed at UTK enables continuous determination of excess volumes and polarizabilities by an interferometric technique. The polarizability is a fundamental molecular property and closely connected to the definition of the intermolecular potential. The measurements are therefore of theoretical interest."

Alexander Van Hook received a B.S. degree in chemistry and philosophy from The College of the Holy Cross and M.S. and Ph.D. degrees from Johns Hopkins University. After postdoctoral experience at Brookhaven National Laboratory he joined UTK in 1962 where he is currently Professor of Chemistry. Van Hook has spent study leaves of varying length in Brussels, Belgrade, Budapest, Beijing and Lisbon.

Rebelo, L. P. N.; De Sousa, H. C.; Van Hook, W. A.: Hypercritically enhanced distortion of a phase diagram. The (polystyrene acetaldehyde) system. Journal of Polymer Science B. Polymer Physics. 1997, 35, 631-637.

Imre, A.; Van Hook, W. A.: Continuity of solvent quality in polymer solutions. Poor solvent to -solvent continuity in some polystyrene solutions. Journal of Polymer Science B. Polymer Physics. 1997 35, 1251-1259.

Jakli, Gy.; Van Hook, W. A.: Isotope effects in aqueous systems. Excess thermodynamic properties of 1,3-dimethylurea solutions in H₂O and D₂O. J. Chem. Eng. Data 1997, 42, 1274-1279.

Melnichenko, Y. B.: Anisimov, M. A.; Povodyrev, A.A.; Wignall, G. D.; Sengers, J. V.; Van Hook, W. A.: "Sharp crossover of the susceptibility in polymer solutions near the critical demixing point." Phys. Rev. Letters, 1997, 79, 5266-5269.

Imre, A.; Van Hook, W.A.: "Liquid-liquid equilibria in polymer solutions at negative pressure," Chem. Soc. Reviews, 1998 27, 117-123.

Szydlowski, J.; Van Hook, W.A.: "Studies of liquid-liquid demixing of polystyrene solutions using dynamic light scattering. Nucleation and droplet growth from dilute solution," Macromolecules, 1998, 31, 3255-3265.

Szydlowski, J.; Van Hook, W.A.: "Concentration and temperature dependence of dynamic light scattering for some polystyrene solutions in toluene, cyclohexane, methylcyclohexane and deuteromethylcyclohexane," Macromolecules, 1998, 31, 3266-3274.

Szydlowski, J.; Rebelo, L.P.; Wilczura, H.; Dadmun, M.; Melnichenko, Y.; Wignall, G.D.; Van Hook, W.A.: "Comparison of SANS and DLS hydrodynamic correlation lengths for a polystyrene/methylcyclohexane solution in the vicinity of temperature or pressure induced critical demixing," Physica B. Condensed Matter, 1998, 241/243, 1035-1037.

Szydlowski, J.; Rebelo, L.P.; Wilczura, H.; Van Hook, W.A.; Melnichenko, Y.; Wignall, G.D.: Liquid-liquid demixing from polystyrene solutions. Studies on temperature and pressure dependences using dynamic light scattering and neutron scattering. Fluid Phase Eq., 1998, 150/151, 687-694.

Melnichenko, Y.; Wignall, G.D.; Van Hook, W.A.; Szydlowski, J.; Wilczura, H.; Rebelo, L.P.: "Comparison of inter-and intramolecular correlations of polystyrene in poor and (theta) solvents via small angle neutron scattering," Macromolecules, 1998, 31, 8436-8438.

Imre, A.; Van Hook, W.A.: Liquid-liquid equilibria in polystyrene solutions: the effect of pressure on solvent quality. Recent research developments in polymer science. Transworld, Trivanandrum 1998 2, 539-546.

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