Radiation‐induced polymerization features of aminoalkyl monomers

Abstract

The rate of radical polymerization of vinyl monomers containing ionogenic groups or atoms with an unsplitted pair of electrons depends generally upon the nature of the environment. On polymerization of nitrogencontaining monomers it has been found that the nature of the environment has a considerable effect on the overall rate of reaction and on the value of rate constants of propagation reaction and chain rupture, respectively. This phenomenon is conditioned by intramolecular and intermolecular effects.1-3 Aminoalkyl ethers of acryl acids obtained on the basis of aliphatic and heterocyclic amines refer to that class of monomers.To find out the role of the above-mentioned effects with radiation-induced polymerization of aminoalkyl monomers, authors have investigated the polymerization of /3-N,N-dimethylaminoethylmethacrylate (DMAEMA), D-N,Ndiethylaminoethylmethacrylate (DEAEMA), bi-(dimethylamino)-isopropylmethacrylate (BDMAIPMA), and P-(-N-cytizene) ethylacrylate(CEA).Polymerization has been conducted in vacuum under the action of yirradiation in mass, solution, and solid phase.The kinetics of radiation-induced polymerization of monomers under investigation in mass follow general rules of ordinary vinyl monomers. The absorbed dose increases, covering all systems, with increasing polymer yield (Fig. 1). The rate of polymerization depends upon the dose rate and adheres to V = KZO.5, pointing to the chain rupture in bimolecular mechanism.With radiation-induced polymerization of CEA, however, the monomer conversion of low rates does not exceed 20 percent. This seems to be due to steric effects of cytizene monomer fragments.The comparison of polymerization rates of aminoalkyl monomers of equal conditions makes it possible to arrange them in the following sequence by increasing values of radiation-chemical yields: CEA < DMAEMA < DEAEMA < BDMAIPMA (values G are equal to 2.6 x 102, 1.2 x lo4, 1.9 x lo4, and 2.0 x lo4 M/100 EV, respectively).