Cure Reaction Pathways of Bismaleimide Polymers:  A Solid-State ¹⁵N NMR Investigation

Abstract

The cure reaction pathways of a bismaleimide resin with a diamine are investigated using solid-state 15 N NMR spectroscopic techniques with specifically labeled monomers. These techniques provide clear identification of at least three different reaction pathways in the curing resin, one of which has previously been only postulated. In the homopolymerized bismaleimide resin system, maleimide ring addition has previously been shown to be the only observable reaction. When co-reacted with an amine, Michael addition of the amine to the maleimide ring has also been observed. Furthermore, a ring-opening aminolysis reaction, which has been observed in solution with specific reagents and conditions, has been suggested to occur under cure conditions. We show conclusively that this aminolysis reaction occurs to a significant extent during the cure of the neat resin and that this product can remain in the network structure even after a high-temperature postcure treatment. The existence of the amide product is demonstrated using bismaleimide resin formulations selectively labeled with 13 C and 15 N at specific sites. The 15 N chemical shifts and the 13 C-15 N scalar couplings are consistent with and confirm the amide product formation. Furthermore, under certain cure and postcure conditions, the aminolysis reaction is reversible which may significantly affect the final network structure.

Cure reaction for modified diallylbisphenol A/diaminodiphenylsulfone/bismaleimide

“…For similar reasons we also recently showed that a combination of different cure kinetic models was required to accurately represent a similar modified BMI system. 32 This article reports on our investigation relating the glass-transition temperature and conversion for a BMI system consisting of three main components: BMI (4,4Ј-methylenebis-[maleimidobenzene]), DABPA (2,2Ј-diallylbisphenol A), and 4,4Ј-diaminodiphenylsulfone (DDS). The major reaction types occurring in this type of system containing diallybisphenol have been proposed in the literature 33,34 ( Fig.…”

Thermal, thermoechanical and morphological behavior of Octa (maleimido phenyl) silsesquioxane (OMPS)-cyanate ester nanocomposites

“…2 For example, the moisture absorption rate of CEs is lower than that of epoxy, polyimide and BMI resins. 3,4 Cyanate esters are studied as precursors to carbon-carbon materials because they may be cured without outgassing and they form dense, thermally stable resins. 5 Carbon-carbon composite materials are formed by impregnating continuous carbon fiber cloths or performed with an organic thermoset resin (usually phenolic resins), curing the resin, then followed by high temperature pyrolysis to carbonize the matrix resin.…”

The facile synthesis and optical nonlinearity of hyperbranched polyaspartimides with azobenzene dyes

“…As reported in Refs. [23][24][25][26][27][28][29][30], polyaspartimides, which could be obtained through Michael addition reaction between amine and maleimide compounds, have shown more favorable properties in processing than do the condensation type polyimides.…”