Varying the sequence distribution and hydrogen bonding strength provides highly Heat-Resistant PMMA copolymers

In this study we used free radical copolymerization of methyl methacrylate (MMA) and N-hydroxyphenylmaleimide (HPMI) to synthesize various poly(methyl methacrylate-co-N-hydroxyphenylmaleimide) (PMMA-co-PHPMI) random copolymers possessing high glass transition temperatures (T-g). FTIR and NMR spectroscopy, mass spectrometry, and differential scanning calorimetry (DSC) confirmed the chemical structures, thermal properties, hydrogen bonding interactions, and sequence distributions of these random copolymers. Because the reactivity ratio of MMA and HPMI is very different from that of MMA and maleic anhydride (MA), which prefer to form homopolymers, here we obtained partially alternating copolymers featuring strong intermolecular hydrogen bonding between the PMMA and PHPMI segments, resulting in the value of T-g increasing by up to 90 degrees C relative to that of the pure PMMA homopolymer. In addition, solid state NMR spectra revealed single values for the proton spin-lattice relaxation time in the rotating frame [T-1 rho(H)] over all compositions of these random copolymers, with the relaxation times being shorter than the predicted average, indicating that the free volume had decreased and that the copolymers possessed rigid structures with high values of T-g.

Automated summary

In this study, we synthesized a series of random copolymers of methyl methacrylate (MMA) and N-hydroxyphenylmaleimide (HPMI) using free radical copolymerization. These copolymers exhibited high glass transition temperatures (T-g) due to the strong intermolecular hydrogen bonding between the PMMA and PHPMI segments. The results from various analytical techniques confirmed the chemical structures, thermal properties, hydrogen bonding interactions, and sequence distributions of these copolymers.