The Hildebrand solubility parameter (δ) provides a numerical estimate of the degree of interaction between materials and can be a good indication of solubility, particularly for nonpolar materials such as many polymers. Materials with similar values of δ are likely to be miscible.
The cohesive energy density is the amount of energy needed to completely remove unit volume of molecules from their neighbours to infinite separation (an ideal gas). This is equal to the heat of vaporization of the compound divided by its molar volume in the condensed phase. In order for a material to dissolve, these same interactions need to be overcome, as the molecules are separated from each other and surrounded by the solvent. In 1936 Joel Henry Hildebrand suggested the square root of the cohesive energy density as a numerical value indicating solvency behavior.[1] This later became known as the "Hildebrand solubility parameter". Materials with similar solubility parameters will be able to interact with each other, resulting in solvation, miscibility or swelling.
Uses and limitationsedit
Its principal utility is that it provides simple predictions of phase equilibrium based on a single parameter that is readily obtained for most materials. These predictions are often useful for nonpolar and slightly polar (dipole moment < 2 debyes[citation needed]) systems without hydrogen bonding. It has found particular use in predicting solubility and swelling of polymers by solvents. More complicated three-dimensional solubility parameters, such as Hansen solubility parameters, have been proposed for polar molecules.
The principal limitation of the solubility parameter approach is that it applies only to associated solutions ("like dissolves like" or, technically speaking, positive deviations from Raoult's law): it cannot account for negative deviations from Raoult's law that result from effects such as solvation or the formation of electron donor–acceptor complexes. Like any simple predictive theory, it can inspire overconfidence: it is best used for screening with data used to verify the predictions.[citation needed]
Unitsedit
The conventional units for the solubility parameter are (calories per cm3)1/2, or cal1/2 cm−3/2. The SI units are J1/2 m−3/2, equivalent to the pascal1/2. 1 calorie is equal to 4.184 J.
Given the non-exact nature of the use of δ, it is often sufficient to say that the number in MPa1/2 is about twice the number in cal1/2 cm−3/2. Where the units are not given, for example, in older books, it is usually safe to assume the non-SI unit.
From the table, poly(ethylene) has a solubility parameter of 7.9 cal1/2 cm−3/2. Good solvents are likely to be diethyl ether and hexane. (However, PE only dissolves at temperatures well above 100 °C.) Poly(styrene) has a solubility parameter of 9.1 cal1/2 cm−3/2, and thus ethyl acetate is likely to be a good solvent. Nylon 6,6 has a solubility parameter of 13.7 cal1/2 cm−3/2, and ethanol is likely to be the best solvent of those tabulated. However, the latter is polar, and thus we should be very cautions about using just the Hildebrand solubility parameter to make predictions.
^ abJohn Burke (1984). . Archived from the original on 6 June 2011. Retrieved 2013-12-04.
^ abcd"Examples of Solubility Parameters". Retrieved 2007-11-20.
^ abcdefVandenburg, H.; et al. (1999). "A simple solvent selection method accelerated solvent extraction of additives from polymers". The Analyst. 124 (11): 1707–1710. Bibcode:1999Ana...124.1707V. doi:10.1039/a904631c.
^ abcKwok A. Y.; Qiao G. G.; Solomon D. H. (2004). "Synthetic hydrogels 3. Solvent effects on poly(2-hydroxyethyl methacrylate) networks". Polymer. 45 (12): 4017–4027. doi:10.1016/j.polymer.2004.03.104.
Bibliographyedit
Barton, A. F. M. (1991). Handbook of Solubility Parameters and Other Cohesion Parameters (2nd ed.). CRC Press.
Barton, A. F. M. (1990). Handbook of Polymer Liquid Interaction Parameters and Other Solubility Parameters. CRC Press.
External linksedit
Abboud J.-L. M., Notario R. (1999) Critical compilation of scales of solvent parameters. part I. pure, non-hydrogen bond donor solvents – technical report. Pure Appl. Chem. 71(4), 645–718 (IUPAC document with large table (1b) of Hildebrand solubility parameter (δH))
January 01, 1970
hildebrand, solubility, parameter, provides, numerical, estimate, degree, interaction, between, materials, good, indication, solubility, particularly, nonpolar, materials, such, many, polymers, materials, with, similar, values, likely, miscible, contents, defi. The Hildebrand solubility parameter d provides a numerical estimate of the degree of interaction between materials and can be a good indication of solubility particularly for nonpolar materials such as many polymers Materials with similar values of d are likely to be miscible Contents 1 Definition 2 Uses and limitations 3 Units 4 Examples 5 See also 6 References 6 1 Notes 6 2 Bibliography 7 External linksDefinition editThe Hildebrand solubility parameter is the square root of the cohesive energy density d D H v R T V m displaystyle delta sqrt frac Delta H v RT V m nbsp The cohesive energy density is the amount of energy needed to completely remove unit volume of molecules from their neighbours to infinite separation an ideal gas This is equal to the heat of vaporization of the compound divided by its molar volume in the condensed phase In order for a material to dissolve these same interactions need to be overcome as the molecules are separated from each other and surrounded by the solvent In 1936 Joel Henry Hildebrand suggested the square root of the cohesive energy density as a numerical value indicating solvency behavior 1 This later became known as the Hildebrand solubility parameter Materials with similar solubility parameters will be able to interact with each other resulting in solvation miscibility or swelling Uses and limitations editIts principal utility is that it provides simple predictions of phase equilibrium based on a single parameter that is readily obtained for most materials These predictions are often useful for nonpolar and slightly polar dipole moment lt 2 debyes citation needed systems without hydrogen bonding It has found particular use in predicting solubility and swelling of polymers by solvents More complicated three dimensional solubility parameters such as Hansen solubility parameters have been proposed for polar molecules The principal limitation of the solubility parameter approach is that it applies only to associated solutions like dissolves like or technically speaking positive deviations from Raoult s law it cannot account for negative deviations from Raoult s law that result from effects such as solvation or the formation of electron donor acceptor complexes Like any simple predictive theory it can inspire overconfidence it is best used for screening with data used to verify the predictions citation needed Units editThe conventional units for the solubility parameter are calories per cm3 1 2 or cal1 2 cm 3 2 The SI units are J1 2 m 3 2 equivalent to the pascal1 2 1 calorie is equal to 4 184 J 1 cal1 2 cm 3 2 523 125 J 1 2 10 2 m 3 2 4 184 J 1 2 0 01 m 3 2 2 045483 103 J1 2 m 3 2 2 045483 106 J m3 1 2 2 045483 MPa1 2 Given the non exact nature of the use of d it is often sufficient to say that the number in MPa1 2 is about twice the number in cal1 2 cm 3 2 Where the units are not given for example in older books it is usually safe to assume the non SI unit Examples editSubstance d 1 cal1 2 cm 3 2 d MPa1 2 n Pentane 7 0 14 4 n hexane 7 24 14 9 Diethyl Ether 7 62 15 4 Ethyl Acetate 9 1 18 2 Chloroform 9 21 18 7 Dichloromethane 9 93 20 2 Acetone 9 77 19 9 2 propanol 11 6 23 8 Ethanol 12 92 26 5 PTFE 6 2 2 Poly ethylene 7 9 2 Poly propylene 8 2 3 16 6 Poly styrene 9 13 2 Poly phenylene oxide 9 15 2 PVC 9 5 3 19 5 Polyurethane PU PUR 8 9 3 PET 10 1 3 20 5 Nylon 6 6 13 7 3 28 Poly methyl methacrylate 9 3 3 19 0 Hydroxyethyl methacrylate 25 26 4 poly HEMA 26 93 4 Ethylene glycol 29 9 4 33 0 From the table poly ethylene has a solubility parameter of 7 9 cal1 2 cm 3 2 Good solvents are likely to be diethyl ether and hexane However PE only dissolves at temperatures well above 100 C Poly styrene has a solubility parameter of 9 1 cal1 2 cm 3 2 and thus ethyl acetate is likely to be a good solvent Nylon 6 6 has a solubility parameter of 13 7 cal1 2 cm 3 2 and ethanol is likely to be the best solvent of those tabulated However the latter is polar and thus we should be very cautions about using just the Hildebrand solubility parameter to make predictions See also editSolvent Hansen solubility parametersReferences editNotes edit a b John Burke 1984 Part 2 Hildebrand Solubility Parameter Archived from the original on 6 June 2011 Retrieved 2013 12 04 a b c d Examples of Solubility Parameters Retrieved 2007 11 20 a b c d e f Vandenburg H et al 1999 A simple solvent selection method accelerated solvent extraction of additives from polymers The Analyst 124 11 1707 1710 Bibcode 1999Ana 124 1707V doi 10 1039 a904631c a b c Kwok A Y Qiao G G Solomon D H 2004 Synthetic hydrogels 3 Solvent effects on poly 2 hydroxyethyl methacrylate networks Polymer 45 12 4017 4027 doi 10 1016 j polymer 2004 03 104 Bibliography edit Barton A F M 1991 Handbook of Solubility Parameters and Other Cohesion Parameters 2nd ed CRC Press Barton A F M 1990 Handbook of Polymer Liquid Interaction Parameters and Other Solubility Parameters CRC Press External links editAbboud J L M Notario R 1999 Critical compilation of scales of solvent parameters part I pure non hydrogen bond donor solvents technical report Pure Appl Chem 71 4 645 718 IUPAC document with large table 1b of Hildebrand solubility parameter dH Retrieved from https en wikipedia org w index php title Hildebrand solubility parameter amp oldid 1176854743, wikipedia, wiki, book, books, library,
