The Preparation of Methyl Methacrylate/Methacrylic Anhydride Copolymers from PMMA and Dialkyl Amines via Reactive Extrusion
Although the imidization reaction of PMMA has been studied for many years1–4 recently, the study of this reaction by reactive extrusion processes has led to some interesting and unexpected results.5–7,11 Specifically, the first step of this reaction is now believed to be due to an unusual alkyl oxygen cleavage reaction resulting in the formation of methacrylic acid and methacrylic anhydrides.7 In an attempt to corroborate this mechanism, we have conducted some model reactions using dimethyl amine and PMMA in a twin screw, counter-rotating, non-intermeshing extruder. According to the proposed mechanism,7 the reaction products should be derived from these alkyl-oxygen cleavage products. However, by use of a dialkyl amine, the intermediate products should be prevented from cyclization to imide products, and therefore should be trapped at an intermediate stage. This should allow some evidence of the reaction pathway to be observed. Also, analysis of the gaseous products should be indicative of the reaction pathway.
KeywordsMethacrylic Acid Acidic Functionality Total Titratable Acidity Reactive Extrusion Excess Amine
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