The preparation and structural characterization of polymeric herbicides consisting of 2,4-dichlorophenoxyacetic acid and 4-chloro-2-methylphenoxyacetic acid either covalently or ionically bound to linear and crosslinked polymers are described, Poly(styrene/divinylbenzene) resins, crosslinked polysaccharides, and home and copolymers of oligo(oxyethylene) monomethacrylates were used as polymeric supports Herbicide binding was attained by nucleophilic displacement, esterification and ion-exchange reactions. Herbicide release from polymer beads was monitored in water solution buffered at pH 4, 7 and 9. The observed release profiles are discussed in terms of polymer inherent structural features. The release kinetics did not fit simple diffusional schemes while could be satisfactorily reproduced by the contemporary occurrence of two exponential decay processes, differing by two orders of magnitude in their rates.
Hydrogel-type polymers in the controlled release of phytodrugs
SOLARO, ROBERTO;D'ANTONE, SALVATORE;CHIELLINI, EMO;
1994-01-01
Abstract
The preparation and structural characterization of polymeric herbicides consisting of 2,4-dichlorophenoxyacetic acid and 4-chloro-2-methylphenoxyacetic acid either covalently or ionically bound to linear and crosslinked polymers are described, Poly(styrene/divinylbenzene) resins, crosslinked polysaccharides, and home and copolymers of oligo(oxyethylene) monomethacrylates were used as polymeric supports Herbicide binding was attained by nucleophilic displacement, esterification and ion-exchange reactions. Herbicide release from polymer beads was monitored in water solution buffered at pH 4, 7 and 9. The observed release profiles are discussed in terms of polymer inherent structural features. The release kinetics did not fit simple diffusional schemes while could be satisfactorily reproduced by the contemporary occurrence of two exponential decay processes, differing by two orders of magnitude in their rates.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
