The paper describes the synthesis and characterization of six copolyme
rs of methyl methacrylate (MMA) and N-phenyl maleimide (NPM). Thermal
stability of PMMA was markedly improved by incorporation of even a ver
y low mole fraction of NPM in the backbone. An increase in mole fracti
on of NPM from 0.0979 to 0.4766 only marginally affected thermal stabi
lity.