title: Phase-selective solubility of poly(N-alkylacrylamide)s.
abstract: The extent of the phase-selective solubility of poly(N-alkylacrylamide)s was studied by UV-vis and fluorescence spectroscopy using poly(N-isopropylacrylamide) and poly(N-octadecylacrylamide) as representative polar and nonpolar poly(N-alkylacrylamide)s in a mixture of polar and nonpolar thermomorphic solvents. Phase-selective solubilities of greater than 10000:1 were seen with each labeled polymer in polar and nonpolar solvents such as heptane and DMF or heptane and 90% EtOH-H(2)O. Using a poly(N-acryloxysuccinimide) as a common precursor, a pool-split synthesis was devised to prepare a library of poly(N-alkylacrylamide)s whose members varied only in the size of their N-alkyl substituent. The solubilities of these library members were measured in both the polar and nonpolar phases of a thermomorphic heptane/90% EtOH-H(2)O mixture at 25 degrees C. Such solvent mixtures are miscible hot (70 degrees C) and biphasic cold (25 degrees C). The results show that poly(N-pentylacrylamide) is selectively soluble (>99.5%) in the polar EtOH-rich phase at rest. Poly(N-alkylacrylamide)s with larger N-alkyl groups are predominantly (C(6), 85%; C(7), 95%) or exclusively (>C(8), >99.5%) in the heptane-rich phase at rest.
authors.affiliation: Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, TX 77842-3012, USA. bergbreiter@tamu.edu
authors.forename: David E
authors.initials: DE
authors.lastname: Bergbreiter
authors.forename: Reagan
authors.initials: R
authors.lastname: Hughes
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Besinaiz
authors.forename: Chunmei
authors.initials: C
authors.lastname: Li
authors.forename: Philip L
authors.initials: PL
authors.lastname: Osburn