DYNAMIC LIGHT-SCATTERING STUDY OF 1-NAPHTHYLACETIC ACID POLYMERIC DERIVATIVE, A NOVEL PLANT HORMONE

This paper describes the dynamics of new slow release formulations of plant growth regulator (PGR) 1-naphthylacetic acid (NAA) in aqueous so lution. The new PGR formulations are water-soluble copolymers derived from acrylamide and vinyl chloroethyl ether, containing side linkages of NAA the latter being released after hydrolysis. From the observed p hoton correlation spectra of the polarized scattered light of the wate r-soluble PGRs, the distribution of relaxation times is computed by me ans of a direct Laplace transformation The results of the light scatte ring experiments suggest that the incorporation of the hydrophobic nap hthyl group dramatically affects the conformation of the parent polyme r. The interactions between the hydrophobic NAA groups lead to the for mation of interpolymeric micellar structures. The hydrodynamic radius R-h which is 42 Angstrom for the parent polymer (PF1), increases to 70 Angstrom for the NAA polymeric ester with 1.94% mol content (PF2) and becomes 82 Angstrom by increasing the amount of the hydrophobic subst ituent to 3.54 mol.% content (PF3). The scattering intensities and app arent hydrodynamic radii display a systematic drop as a function of ti me due to the loss of the NAA linkages and R-h becomes 58 Angstrom for PF2 and 68 Angstrom for PF3, 116 h after the preparation of the water polymeric solutions. (C) 1998 Elsevier Science Ltd. All rights reserv ed.