Hydrophilic glycols

Cationic hydrophilic Glycol chitosan, DEAE-dextran, poly(ethyleneimine), poly(trimethylaminoethyl methacrylate) iodide salt 0.5 M acetic acid with 0.3 M NaiSO, or 0.8 M NaNO.,... 

NEB and almost all chemical reactions in foods are thought to cease in systems that are below a of 0.23 to 0.43, the typical range of the moisture monolayer value (Labuza et al., 1969 Rockland and Nishi, 1980). In Figure 20.5b, this trend appeared as expected for the control formulation, which contained no humectant. However, upon the addition of hydrophilic glycols as humectants (which were liquids at the test temperature and thus miscible in water), the at which the maximum reaction rate occurred shifted to a much lower value. Propylene glycol showed a maximum rate at a of about 0.2, with a rate equal to the maximum rate of the control at a a of 0.8. 

A key factor influencing the degradation rate of polyesters is the hydrophilicity of the polymer matrix, which also governs the rate at which water diffuses into the polymer matrix. The hydrophilicity of a polymer is inversely proportional to the number of carbon atoms in its monomer unit (i.e., hydrophilicity glycolic acid (GA)> lactic acid (LA) >caprolactone>decalactone), the polarity of its functional side groups (i.e., hydrophilicity NH2>OH>CH3), and the configuration of the atoms within the monomer (i.e., (CH2)e > benzene). Numerous studies have demonstrated that the degradation rate of a polyester scales with its... 

The hydrophilic parts can contain oxygenated groups (glycol ether types) or amines. The first detergents used amine and phosphoric acid salts or... 

Materials that typify thermoresponsive behavior are polyethylene—poly (ethylene glycol) copolymers that are used to functionalize the surfaces of polyethylene films (smart surfaces) (20). When the copolymer is immersed in water, the poly(ethylene glycol) functionaUties at the surfaces have solvation behavior similar to poly(ethylene glycol) itself. The abiUty to design a smart surface in these cases is based on the observed behavior of inverse temperature-dependent solubiUty of poly(alkene oxide)s in water. The behavior is used to produce surface-modified polymers that reversibly change their hydrophilicity and solvation with changes in temperatures. Similar behaviors have been observed as a function of changes in pH (21—24). 

Humectants. In certain foods, it is necessary to control the amount of water that enters or exits the product. It is for this purpose that humectants are employed. Polyhydric alcohols (polyols), which include propylene glycol [57-55-6], C2Hg02, glycerol [56-81-5], C HgO, sorbitol [50-70-4], and mannitol [69-65-8], contain numerous hydroxyl groups (see Alcohols,polyhydric). Their stmcture makes them hydrophilic and... 

Propylene oxide polymers are less hydrophilic and also lower in cost and may be prepared by polymerising the oxide in the presence of propylene glycol as an initiator and a caustic catalyst at about 160°C. They have the general structure... 

Block copolymers of ethylene oxide and propylene oxide, less hydrophilic than poly(oxyethylene) glycol and more reactive than the propylene oxide polymers, were introduced by Wyandotte Chemical (USA) under the trade name Pluronic. 

Nonionic hydrophilic Polyethylene glycol Soluble starch, methyl cellulose, pullulan Dextran Above samples plus hydroxyethyl cellulose, polyvinyl alcohol, polyacrylamide Distilled water 0.01 N NaOH DMSO Buffer or salt solution (e.g., 0.1— 0.5 M NaNO,)... 

Nonionic, hydrophilic Polyethylene oxide, polyethylene glycol Polyviny alcohol, hydroxyethyl cellulose, polyacrylamide Pure water 0.1-0.2 M salt/buffer, pH 7... 

The solubility of latex in water can be improved by replacing the solvent used in the system. Initially, the water is removed and than a hydrophobic organic solvent is replaced by a hydrophilic solvent, which has a boiling point above 100 C. This last solvent can be ethylene glycol, diethyl ether of diethylene glycol, monoethyl ether of ethylene glycol, or polyethylene glycols. This treatment results in a pastelike composition that can be easily mixed with water and used as a final product. 

Sorbitan esters of fatty acids are well known. Similar products can be made from ether carboxylic acids and sorbitol without an acid catalyst with a good color [39]. The advantage of these products is that the hydrophilicity can be adjusted by the polyethylene glycol content in the ether carboxylic acid. 

Dendrimer micelles of this type have been formulated as drug delivery vehicles. Dendrimers with a hydrophobic interior have been used to entrap a hydrophobic drug such as indomethacin. This is retained because of the hydrophilic periphery containing ethylene glycol functional groups, and is released slowly because of the collapsed configuration of the interior, through which molecular diffusion is obstructed. 

The contemporaneous presence of different solubilizates sometimes involves competition for the micellar binding sites [31], For instance, from an analysis of the heats of solution of benzene and water in solutions of reversed micelles of tehaethylene glycol dodecyl ether in decane, a competition between water and benzene for the surfactant hydrophilic groups was shown [32],... 

Solubilization of a graft copolymer comprising a hydrophobic poly(dodecyl-methacrylate) backbone and hydrophilic poly(ethylene glycol) monomethyl ether side chains in water/AOT/cyclohexane w/o microemulsions was rationalized in terms of the backbone dissolved in the continuous apolar phase and the side chains entrapped within the aqueous micellar cores [189],... 

Phase transfer catalysis (PTC) refers to the transfer of ions or organic molecules between two liquid phases (usually water/organic) or a liquid and a solid phase using a catalyst as a transport shuttle. The most common system encountered is water/organic, hence the catalyst must have an appropriate hydrophilic/lipophilic balance to enable it to have compatibility with both phases. The most useful catalysts for these systems are quaternary ammonium salts. Commonly used catalysts for solid-liquid systems are crown ethers and poly glycol ethers. Starks (Figure 4.5) developed the mode of action of PTC in the 1970s. In its most simple... 

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