Radical polymerization of N-(alkyl-substituted phenyl)maleimides: synthesis of thermally stable polymers soluble in nonpolar solvents

To synthesize thermally stable vinyl polymers soluble in organic solvents, radical polymerization of 16 kinds of N-(alkyl-substituted phenyl)maleimides (RPhMI) was investigated. The yield and molecular weight of the polymers obtained decreased with an increase in both number and bulkiness of the alkyl substituents in the ortho position but increased when these substituents were introduced into meta and para positions. It was found that the resulting polymers were soluble in common organic solvents including benzene, although unsubstituted poly(N-phenylmaleimide) was soluble only in polar solvents, and they they showed an excellent thermal stability as well as poly(N-phenylmaleimide); i.e. no weight loss was observed below 370 deg C in nitrogen. These RPhMI monomers were readily copolymerized with styrene and methyl methacrylate, and their reactivities were also dependent on the position, number, and bulkiness of the substituents introduced. Graphs. 25 ref.--AA