Optimisation of Glycerol and Itaconic Anhydride Polycondensation.

Glycerol polyesters have recently become objects of interest in tissue engineering. Barely known so far is poly(glycerol itaconate) (PGItc), a biocompatible, biodegradable polyester. Due to the presence of a C=C electron-acceptor moiety, it is possible to post-modify the product by Michael additions to change the properties of PGItc. Thus, using PGItc as one of the elements of cellular scaffold crosslinked in situ for bone tissue regeneration seems to be a very attractive yet unexplored solution. This work aims to optimize the synthesis of PGItc to obtain derivatives with a double bond in the side chain with the highest conversion rates. The experiments were performed with itaconic anhydride and glycerol using mathematical planning of experiments according to the Box-Behnken plan without solvent and catalyst. The input variables of the process were the ratio of the OH/COOH, temperature, and reaction time. The optimised output variables were: the degree of esterification (EDtitr), the degree of esterification calculated from the analysis of 1H NMR spectra (EDNMR), and the degree of itaconic anhydride conversion-calculation based on 13C NMR spectra (%X13CNMR). In each of statistical models, the significance of the changed synthesis parameters was determined. Optimal conditions are when OH/COOH ratio is equal to 1.5, temperature is 140 °C and time of reaction is 5 h. The higher OH/COOH ratio, temperature and longer the experiment time, the higher the value of the degree of esterification and the degree of anhydride conversion.

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 °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.

From Poly(glycerol itaconate) Gels to Novel Nonwoven Materials for Biomedical Applications.

Electrospinning is a process that has attracted significant interest in recent years. It provides the opportunity to produce nanofibers that mimic the extracellular matrix. As a result, it is possible to use the nonwovens as scaffolds characterized by high cellular adhesion. This work focused on the synthesis of poly(glycerol itaconate) (PGItc) and preparation of nonwovens based on PGItc gels and polylactide. PGItc gels were synthesized by a reaction between itaconic anhydride and glycerol. The use of a mixture of PGItc and PLA allowed us to obtain a material with different properties than with stand-alone polymers. In this study, we present the influence of the chosen ratios of polymers and the OH/COOH ratio in the synthesized PGItc on the properties of the obtained materials. The addition of PGItc results in hydrophilization of the nonwovens' surface without disrupting the high porosity of the fibrous structure. Spectral and thermal analyzes are presented, along with SEM imagining. The preliminary cytotoxicity research showed that nonwovens were non-cytotoxic materials. It also helped to pre-determine the potential application of PGItc + PLA nonwovens as subcutaneous tissue fillers or drug delivery systems.