Gels à base d’acrylamide et de 4-VP -Application à la libération contrôlée des molécules organiques.

Abstract

This study an objective firstly :the synthesis of the poly (4- vinyl pyridine) with a series of these derived products in the shape of copolymers poly(4- vinyl pyridine N- octyl bromed)at different percentages of quaternization named :P4VPC8Br20%, P4VPC8Br48.8% and P4VPC8Br72%. These copolymers have been characterized by conductimetry,NMR1H,NMR13C and GTA. The thermodynamic behaviour associated to the potentiometric titration of the copolymers has been realized in the temperature interval from (293,16K to 333,16K) according to the concentrations included between (0,25 .10-4 mmol/dm3 to 12,3 .10-4 mmol/dm3).The negative values of the free energy of dissociation (Gdiss) according to the degree of neutralization are due to the sterique and electrostatic effect of the alkylic chains .the positive values of H0 and S0 confirm the reaction, disorganization and spontaneity. The transition of the copolymers chains conformation has been influenced by the presence of hydrophobic-hydrophilic and hydrophobic-hydrophobic interactions. The copolymers viscosimetric study (P4VPC8Br20%, P4VPC8Br48.8% P4VPC8Br72%) in aqueous solutions has been realized by varying the neutralization degree  , the quaternization rate and the copolymer concentration. Later we have elaborated a hydrogel [AM-cross-4VP] fundamentally of acrylamide (AM) and (4VP)vinyl pyridine by adiabatic copolymerization using radical progress depending on the ratio water/monomers in aqueous solutions. Charged hydrogels have been obtained by hydrolyse of [AM-cross-4VP] by NaOH at 60°C. their phisico-chimic behaviour has been checked :swilling ,nature of the absorbent surface, pH and the floating salinity effect. These copolymers have been perfectly characterized by GTA, SED and RI.