Poly(ethylene-co-methacrylic acid) ionomer dynamic phase composition and polymer chain mobility characterization by time domain NMR

We report a convenient approach for characterizing poly(ethylene-co-methacrylic acid) (EMAA) using time domain NMR. The T₂ relaxation curve of EMAA can be obtained by the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence and analyzed with a three-component model. The dynamic phase distribution (the aggregation of relaxation components with similar mobility) and overall polymer chain mobility results showed good agreement with well-known EMAA ionomer properties and Hahn Echo pulse sequence experiments. Subsequently, plasticizer's impact on the EMAA network was studied with the method established here. Plasticizer-induced dynamic phase redistribution and chain mobility changes can be revealed by time domain NMR (TD NMR) analysis, enabling researchers to better understand the plasticizer–polymer interaction mechanism. In conclusion, TD NMR characterization of EMAA polymers provided a new perspective on the structural features and dynamics of these materials. The method has the potential to be adopted in R&D labs, processing labs, or plant quality assurance/quality control.