A 3-DIMENSIONAL PHASE-BOUNDARY MODEL FOR DIFFUSION-PROCESSES INVOLVEDIN REACTIONS OF CROSS-LINKED POLYMERIC AMINES WITH LOW-MOLECULAR-WEIGHT ESTERS

The reactivity of amino groups attached to N-N'-methylene-bis-acrylami de (NNMBA)-and triethyleneglycol dimethacrylate (TEGDMA)-crosslinked p olyacrylamide gels (2-20 mol% crosslinked) has been investigated by fo llowing the aminolysis of p-nitrophenyl ester of benzoyl glycine in a mixed solvent. A differential method was employed for following the ra te of aminolysis reaction at definite intervals of time. The extent of aminolysis was found to be maximum between 25 and 35 min after initia tion for these resins. The rate constants were calculated using the eq uation for three-dimensional phase boundary model with spherical symme try and three-dimensional diffusion model. The reaction appears to be a phase boundary process up to 40 min after initiation and thereafter is fully controlled by three-dimensional diffusion. The rate constants do not show any dispersion when this model is used.