ANALYSIS OF CARILITE OLIGOMERS AND THEIR FUNCTIONALIZATION WITH FURFURYLAMINE AT LOW CONVERSION BY GPC, NMR AND ESI-MASS SPECTROSCOPIES

Abstract

Background/Objectives: Carilite oligomers may be easily functionalized with primary amines, such as furfuryl amine, through the Paal-Knorr reaction, converting polymeric 1,4-diketone groups into N-substituted pyrroles with pendant furanyl groups. The resulting oligomers allow producing polymer and polymer composites materials by adding a bifunctional dienophile, leading to reversible crosslinking through the Diels-Alder reaction. The extent of conversion in the Paal Knorr reaction should determine the amount of polymer chains showing two or more furanyl dienes, condition necessary for extended crosslinking. Thus, the objectives of this work consisted of i) to characterize a sample of Carilite oligomers (PK₃₀), ii) to calculate the probabilistic distribution of the N-substituted pyrroles in the oligomer chains as a function of the diketone conversion, and iii) to compare the prediction with experimental data of a sample obtained after reaction between PK₃₀ and furfuryl amine aiming at 20 % of conversion. Methods: GPC, NMR, and ESI mass spectroscopies are used for the analysis of the polymers. Poisson distribution and one-dimensional hard-dimer exclusion models have been applied for probabilistic calculations. Results: Carilite oligomers are a polydisperse mixture where the most abundant molecules present 1 – 16 ketone moieties. After functionalization, the most abundant derivatized molecules consist of oligomers functionalized with only one furfuryl amino residue. Good matching with the predictions were found. Conclusions: The use of NMR combined with ESI-mass spectroscopy has served to understand the molecular structure of Carilite oligomers and their furfuryl amine-functionalized derivatives. This allows determining refined molecular weights that allow calculating effective conversion aimed and, in combination with the probabilistic predictions, obtaining insights of the expected Fu content per chain, contributing to the improvement of design, handling, and control strategies for reversibly crosslinked polymer matrices.