Infinite-dilution activity coefficients of polar and nonpolar solvents in solutions of hyperbranched polymers

Infinite-dilution activity coefficients are measured for several polar and nonpolar solvents in hyperbranched polymers using inverse gas chromatograph y in the temperature range 40-160 degrees C. Two kinds of polymers are stud ied: comb polymers and dendritic polymers. The combs are poly(styrene-co-ma leic anhydride) with alkyl side chains of different lengths (C12, C22). The solvents are: acetone, toluene, tetrahydrofuran (THF), and chloroform. Sol vent solubility in the combs depends on the ratio between the polar backbon e and the nonpolar side chain of the polymer. The dendrimers are amine-term inated poly(propylenimine) of generation 2 to 5. The solvents are: methanol , ethanol, ethyl acetate, toluene, and THF. Solvent activity coefficients c hange with respect to the dendrimer generation number, reaching a minimum a t generation 4. Because the dendrimers are basic, the solvent quality is hi gher for slightly acidic solvents, such as methanol and ethanol. Flory's in teraction parameters are calculated for the solvent/dendrimer systems.