Polymer-water partition coefficient

Kamlet MJ, Abraham MH, Doherty RM, Taft RW (1984) Solubility properties in polymers and biological media. 4. Correlation of octanol/water partition coefficients with solvatochromic parameters. J Am Chem Soc 106 464-466. 

By using a PES with a different thickness, one can conveniently change the AV ratio. This approach permits some control over the time required to reach equilibrium concentrations. Bartkow et al. (2004) has reported an excellent example of the impact of ratio or thickness on the time to equilibrium. These investigators showed that a 200 pm thick PE sheet took twice as long to reach equilibrium in air as a 100 pm thick PE sheet. In theory, changing membrane thickness will not affect polymer diffusivity and equilibrium membrane-water partition coefficients (I mwS) or solubility coefficients ( p). However, in practice different values of (membrane-air partition coefficient) and membrane... 

RW Taft, MH Abraham, GR Famini, RM Doherty, JL Abboud, MJ Kamlet. Solubility properties in polymers and biological media 5 an analysis of the physicochemical properties which influence octanol-water partition coefficients of aliphatic and aromatic solutes. J. Pharm. Sci. 74 807-814 (1985). 

An advantage of defining the problem in this manner is that the partition coefficient has become a central property in quantitative structure-activity relationships (QSAR) and a large data base of P values is available in the medicinal chemistry literature (22-24). In particular, if a correlation (Equation 15) between the polymer-water and octanol-water partition coefficients can be established for a series of solutes, it becomes possible to utilize log P (oc-tanol/water) value as a reference point from which to calculate the polymer-water value. 

The absorption was correlated to the octanol-water partition coefficients of the drugs, suggesting that prediction of absorption from partition data is possible [30, 31]. Polymers such as Nylon-6 (polycaprolactam) are known to adsorb drug substances such as benzocaine [32],... 

Hayward, D.S., Kenley, R.A., Jenke, D.R. (1990) Interactions between polymer containers and parental solutions the correlation of equihbrium constants for polymer-water partitioning with octanol-water partition coefficients. Inti. J. Pharm. 59(3), 245-253. 

Calculation of octanol/water partition coefficients. SciLogW for aqueous solubility prediction. SciPredictor for protein secondary structure and homology modeling. SciPolymer for polymer property estimation. PCs under Windows. CAD Gene for gene constructs. Macintosh. 

The lipophilicity of PSA polymers, which is markedly affected by chemical composition, may influence drug solubility (Table 5). In general, acrylic copolymers have medium lipophilicity compared with other PSA polymers, and have the most excellent drug solubility. A suitable lipophilicity of copolymers can be obtained by changing the compositional content of comonomers. The lipophilicity of acrylic copolymers can be roughly estimated by the theoretical calculation of the hydrophobic parameters of copolymers according to the hydrophobic fragments of each comonomer, or the calculation of the octanol-water partition coefficients (log PC). ... 

Kamlet, M.J., Abraham, M.H., Doherty, R.M. and Taft, R.W. (1984). Solubility Properties in Polymers and Biological Media. 4. Correlations of Octanol/Water Partition Coefficients with Solvatochromic Parameters. J.Am.Chem.Soc., 106,464-466. 

K is the octanol/water partition coefficient, k is the rate of elimination due to permeation through capillaries, D, is the diffusion coefficient of the drug in the brain. The following values are assumed, consistent with results from polymer delivery to rats and rabbits radius of spherical implant, ft = 1.5 mm mass of implant, M = lOmg drug loading in implant = 10%. 

Kamlet Ml, Abboud J-LM, Abraham MH,Taft RW (1983) Linear solvation energy relationships. 23. A comprehensive collection of the solvatochromic parameters tt, a, and p, and some methods for simplifying the generalized solvatochomic equation. J Org Chem 48 2877-2887 Kamlet Ml, Abraham MH, Doherty RM, Taft RW (1984) Solubility properties in polymers and biological media. 4. Correlation of octanol/water partition coefficients with solvatochromic parameters. J Am Chem Soc 106 464-466. 

Concentrations in Water and Particles. In order to obtain the rates of reaction, the concentrations of the two monomers and the chain transfer agent in the water and polymer phases were calculated using equilibrium partition coefficients (H). ... 

In view of these potentials for major reductions in preservative efficacy, considerable effort has gone into attempts to devise equations in which one might substitute variously derived system parameters such as partition coefficients, surfactant and polymer binding constants and oil water ratios in order to obtain estimates of residual preservative levels in aqueous phases. Although some modestly successful predictions have been obtained for very simple laboratory systems, they have proved of limited practical value as data for many of the required parameters are unavailable for technical grade ingredients or for the more complex commercial systems. 

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