Kinetics of formation of a linear polymer-polymer network system in the presence of 3d metal chelates

Abstract

For semi-interpenetrating polymer networks (semi-IPNs) based on an incompatible polyurethane network/linear polymethylmethacrylate pair formed in situ in the presence of 3d metal chelates, we have studied the effect of the system composition on the kinetics of formation of the components and the nature of complex formation between the metal compound and the polymer matrix. The ratio of the system components has been shown to have an effect on the selection of the macroligand in formation of complexes of the metal chelate with the polar groups of the semi-IPN, where the general character of the kinetic behavior for the formation of the network and the linear polymer is preserved.Key words: polyurethane network, linear polymethylmethacrylate, kinetics, EPR, complexes of 3d metal chelates.In recent years, scientific and practical interest has been stimulated in the problem of the compatibility of topologically connected binary polymer mixtures: interpenetrating polymer networks (IPNs), semi-interpenetrating polymer networks (semi-IPNs), mixtures of linear polymers formed in situ. Such systems consist of linear and/or networked components, not chemically bonded and interlaced with each other. They are characterized by incomplete phase separation, due to kinetic factors and diffusional constraints. The faster the reaction rate for the formation of the components of the mixture, the less the system should experience phase separation [1].Another important factor affecting the process of phase separation is specific interactions in the system between its components. Donor-acceptor bonding of polar groups from two incompatible components of the mixture promotes incompleteness of phase separation, like the kinetic conditions and diffusional constraints. Targeted slowing of phase separation in such systems can be done by introducing special additives (compatibilizers), forming chemical and/or donor-acceptor bonds with the components of the mixture [2-6].We know [7] that chelates of many metals are capable of strong specific interaction with compounds containing electron-donor groups. They act as centers for complexation ("coordination" crosslinking nodes), leading to local structurization of the polymer. By "local change in structure," we mean an increase in concentration of some functional groups of the polymer near the metal chelate. The type of functional groups of the polymer matrix forming complexes with a coordination compound with a chelate structure depends significantly on their electron-donor ability and on the electronic configuration of the central metal ion [8][9][10].Metal chelates are often catalysts for the formation of one of the components of the selected mixtures [7], and so introducing them can also have an appreciable effect on the kinetics for the formation of such systems. Bearing in mind the 0040-5760/06/4206-0357