Poly isoimide s

Poly(isoimide)s received interest as intermediates for Pis, because the ring closure of the poly(amic acid) runs faster with carbodiimides, e.g., di-cyclohexylcarbodiimide, in comparison to acetic anhydride. However, the use of a carbodiimide yields the isoimide moiety exclusively, whereas acetic anhydride yields the ordinary imide. However, by the treatment with suitable isomerizing agents, such as 1-hydroxyhenzotriazole, or 3-hydroxy-l,2,3-benzotriazin-4-one, the isoimide can he converted to the imide. This technique is suitable for the synthesis of Uquid thermosetting maleimide resins. 

Poly(isoimide)s are more soluble and exhibit a lower melt viscosity than comparable Pis. For this reason, they are used intentionally as an alternative class of Pis. For example, poly(isomaleimide) can be chain extended with a poly(nucleophilic) monomer, such as a poly(thiol), a poly-(ol), or a poly(amine).  

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The isoimide moiety and the isomerization reaction is shown in Figure 15.7. Poly(isoimide)s can be converted from poly(amic acid)s with car-... 

Poly(isoimide)s are more soluble and exhibit a lower melt viscosity than comparable Pis. For this... 

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