WATER-SOLUBLE COPOLYMERS .53. NA-23 NMR-STUDIES OF HYDROPHOBICALLY-MODIFIED POLYACIDS - COPOLYMERS OF 2-(1-NAPHTHYLACETAMIDO)ETHYLACRYLAMIDE WITH ACRYLIC-ACID AND METHACRYLIC-ACID

Na-23 NMR measurements of the longitudinal (R(1)) and transverse (R(2)) relaxation rates of copolymers of 1% and 10% 2-(1-naphthylacetamido)ethylacrylamide (NAEAM) with acrylic acid (NAA-1 and NAA-10) and methacrylic acid (NMA-1 and NMA-10) have been performed as a function of the degree of ionization. The transverse relaxation was sufficiently biexponential at low alpha to extract R(2s) and R(2f) for NAA-10, NMA-1, and NMA-10. The correlations times, tau(c), and values of P-b chi(2), the product of the fraction of bound ions and the quadrapolar constant, were determined and indicate conformational transitions in NAA-10, NMA-1, and NMA-10. The incorporation of increasing concentration of hydrophobic NAEAM into the polyacids increases chi at low degrees of ionization. The results of the relaxation studies are shown to be consistent with previous viscosity and fluorescence studies on the same systems.