Synthesis and Characterization of Thermoresistant Maleimide Copolymers and their Crosslinked Polymers

Abstract

We fabricated thermosetting maleimide polymers with excellent thermal and optical properties by the sequence-controlled radical copolymerization of N-allylmaleimide (AMI) and N-(2-ethylhexyl)maleimide (EHMI) with diisobutylene (DIB) and postpolymerization reactions. The AAB-type maleimides/DIB copolymers randomly containing an allyl group in the side chain were thermally or photochemically cured using pentaerythritol tetrakis(3-mercaptobutyrate) as a polyfunctional thiol by thiol/ene reaction. The organic-inorganic hybrid was also fabricated by the thiol/ene reaction of the maleimide copolymers containing allyl side groups combined with surface-modified silica nanoparticles. The produced organic-inorganic hybrid was dispersed in tetrahydrofuran. The transparent films of the maleimide copolymers containing the hybrid were obtained by casting and drying. The crosslinked polymers and the organic-inorganic hybrid obtained in this study exhibited excellent thermal stability as well as the high transparency.

Heat resistant and transparent organic–inorganic hybrid materials composed of N‐allylmaleimide copolymer and random‐type SH‐modified silsesquioxane

“…The 1 H NMR spectrum of PEAD confirmed the repeating structure with the composition of AMI/EHMI/DIB = 43/33/24 in molar ratio (Figure ). The production of an RMI‐rich copolymer was quite consistent with the previous results for the synthesis of the RMI copolymers with DIB with approximately 2:1 composition . The 43 mol% content of the AMI repeating unit was sufficiently high as the functional precursor polymer for thermal curing.…”

“…The produced AAB‐type copolymers exhibited higher T g values due to a high content of the RMI units and the bulky structure of the olefin repeating units. It should also be noted that the RMI copolymers including an allyl group in the side chain were successfully fabricated during the copolymerization of N ‐allylmaleimide (AMI) with isobutene or DIB . The soluble copolymers of AMI with isobutene or DIB were produced during the copolymerization under the conditions with a low AMI concentration, while an increase in the AMI concentration readily resulted in the formation of insoluble polymers.…”

“…The soluble copolymers of AMI with isobutene or DIB were produced during the copolymerization under the conditions with a low AMI concentration, while an increase in the AMI concentration readily resulted in the formation of insoluble polymers. The copolymers including allyl groups in the side chain can be used as the precursor polymer for a thermoset system . An AMI‐containing copolymer exhibiting a high T g and excellent optical property is expected to be useful as the precursor polymer for the synthesis of heat‐resistant network polymers by the thiol–ene reaction in the presence of multifunctional crosslinkers.…”

Synthesis of Heat‐resistant Polymers by Thiol–Ene Reaction of N‐Allylmaleimide Copolymers Using Glycoluril Crosslinkers with Rigid Molecular Structures

“…In this study, the curing temperature was fixed as 160 °C, based on the previous results for similar thermal curing systems . The previous reports also confirmed the preference of the use of the equivalent amount of the allyl and mercapto functions for the effective synthesis of network polymers with a high insoluble fraction.…”

“…[26][27][28][29][30] We previously reported that Nallylmaleimide (AMI) copolymers produced by radical copolymerization were valid as the precursor polymers for thermoset systems with or without crosslinking agents. [31][32][33][34][35] The maleimide copolymers exhibited a high glass-transition temperature (T g ) and excellent thermal stability, but the cured materials were brittle. This was due to the intrinsic rigid property of the maleimide copolymers.…”