Poly(glycerol itaconate) Crosslinking via the aza-Michael Reaction-A Preliminary Research

In unsaturated glycerol polyesters, the C=C bond is present. It makes it possible to carry out post-polymerisation modification (PPM) reactions, such as aza-Michael addition. This reaction can conduct crosslinking under in-situ conditions for tissue engineering regeneration. Until now, no description of such use of aza-Michael addition has been described. This work aims to crosslink the synthesised poly(glycerol itaconate) (PGItc; P3), polyester from itaconic acid (AcItc), and glycerol (G). The PGItc syntheses were performed in three ways: without a catalyst, in the presence of p-toluenesulfonic acid (PTSA), and in the presence of zinc acetate (Zn(OAc)2). PGItc obtained with Zn(OAc)2 (150 degrees C, 4 h, G:AcItc = 2:1) was used to carry out the aza-Michael additions. Crosslinking reactions were conducted with each of the five aliphatic diamines: 1,2-ethylenediamine (1,2-EDA; A1), 1,4-butanediamine (1,4-BDA; A2), 1,6-hexanediamine (1,6-HDA; A3), 1,8-octanediamine (1,8-ODA; A4), and 1,10-decanediamine (1,10-DDA; A5). Four ratios of the proton amine group: C=C bond were investigated. The maximum temperature and crosslinking time were measured to select the best amine for the addition product's application. FTIR, 1H NMR, DSC, and TG analysis of the crosslinked products were also investigated.