Characterization of polyacrylamide diblock copolymers by mass spectrometry combined with Mass-remainder analysis (MARA)

Polyacrylamide block copolymers has been extensively used in many fields of science and technology due to their water solubility, biocompatibility and smart and tunable properties. In this study, we used the Mass-remainder analysis (MARA) and the Multi-step Mass-remainder analysis (M-MARA) for the processing of complex MALDI-TOF mass spectra of a series of poly(N-acryloylmorpholine)-block-poly(N-isopropylacrylamide) diblock copolymers. It was found that selection of the MARA base mass unit affects the shape of the Mass remainder versus m/z plots enabling to draw conclusions about the length and diversity of the blocks. Even better and more informative visualization can be achieved by creating 2-step M-MARA plots. The comprehensive characterization of the poly(N-acryloylmorpholine)-block-poly(N-isopropylacrylamide) copolymers with various block length were performed, and the results were confirmed by nuclear magnetic resonance (NMR) spectroscopy.