This work focuses on the methodology to obtain high heat resistant grades of poly(methyl methacrylate) (PMMA) without affecting any of the enabling properties of PMMA through the post reactor modification approach. The post reactor modification approach has been employed to obtain high heat resistant grades of PMMA through blending of PMMA with the high heat copolymers namely, styrene maleic anhydride copolymers (SMA) which have a higher glass transition temperature (Tg) than that of PMMA. The optimum levels of maleic anhydride content (MA %) in the SMA and the preferred composition range of PMMA and SMA blends have been identified wherein the heat properties of PMMA improve substantially without affecting the key properties of PMMA such as optical clarity, mechanical, flow, scratch, and weatherability. There are various analytical tools that are being employed to characterize the resulting blends of PMMA and SMA to gain deeper understanding from the fundamental behavior of these blends for the key applications of interest. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46220.