Ratiometric synthesis of non-traditional polyesters from poly (ethylene glycol) and trimesic acid tethering bioapplication

Non-traditional polyesters from low molecular weight Poly (ethylene glycol) (PEG, M_n 4000) and biocompatible Trimesic acid (TMA) were synthesised through stoichiometric feeding of PEG and TMA in the mole ratios starting from 1:0.5 to 1:5. The melt condensation was carried out under catalytic condition for a limited period of 6 h to prohibit gelation of the entire mass due to over-abundance of the functional groups. The polyesters were formed with substantial soluble yield; at lower acid concentration in the feed e.g. 1:0.5, 1:1 and 1:2-they were mostly branched while at higher concentration e.g. 1:3 and 1:5-they were significantly crosslinked. Nearly all the specimens contained partially reacted TMA molecules in the branch ends which made them pH responsive (the hydrodynamic sizes altered with change in pH). The polymers were characterized using solubility, spectroscopy, viscometry and particle size measurements to establish the microstructure, formation kinetics and branched topology. Nuclear magnetic resonance (¹H NMR) established the maximum extent of branching (65%) at 1:5 mol composition. Suitability for bioapplication of the polyesters was examined from surface texture study and cell cytotoxicity analysis. The scanning electron microscopic (SEM) images portrayed adequate micro voids on the surface, on the other hand, the cytotoxicity study depicted those surfaces could adhere and support the growth of mammalian cells and also successfully survive the MTT assay.