Infinite-Dilution Activity Coefficients of Polar and Nonpolar Solvents in Solutions of Hyperbranched Polymers

摘要

Infinite-dilution activity coefficients are measured for several polar and nonpolar solvents in hyperbranched polymers using inverse gas chromatography in the temeprature range 40-160deg C. Two kinds of polymers are studied: comb polymers and dendritic polymers. The combs are poly(styrene-co-maleic anhydride) with alkyl side chains of different lengths (C12, C22). The solvents are : acetone, toluene, tetrahydrofuran (THF), and chloroform. Solvent solubility in the combs depends on the ratio between the poalr backbone and the nonpolar side chain of hte polymer. The dendrimers are amine-terminated poly(propylenimine) of generation 2 to 5. The solvents are: emthanol, ethanol, ethyl acetate, toluene, and THF. Solvent activity coefficients change with respect to the dendrimer generation number, reaching a minimum at generation 4. Because the dendrimers are basic, the solvent quality is higher for slightly acidic solvents, such as methanol and ethanol. Flory's interaction parameters are calculated for the solvnet/dendrimer systems.