Effect of monomer modification on the physico-chemical properties, degradation and in vitro biocompatibility of polyester bioelastomers

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A careful selection of monomers for biomaterial syntheses is essential for determining and controlling the functionality and biocompatibility of the biomaterials to be produced. Synthetic polyester elastomers based on molecules that are endogenous to the human metabolism have been designed [1]. In earlier studies, several investigators have reported elastic polyesters based on citric acid, in particular polyoctanediol citrate (POC) [2], poly(alkenylene maleate citrate) [3], poly(xylitol-co-citrate) [4] and poly(mannitol citric dicarboxylate) [5]. Although a number of biodegradable elastomers have been developed, most of them require complex and expensive synthetic procedures, which translate into higher manufacturing costs and hinder the …show more content…
FT-IR also demonstrated a broad OH stretch at 3403 & 3489 cm-1 and this could be attributed to the stretching vibration of the hydrogen bonded hydroxyl groups [13]. The bands around 2851 & 2923 cm-1 in both the spectra could be due to the methylene (-CH2-) groups [5] of 1,12-dodecanediol and sebacic acid. The bands at around 1220, 1179 cm-1 in PP1 and at around 1220, 1192 cm-1 in PP2 could be attributed to the C-O stretching vibrations [12]. The alkenyl stretching (C=C) was found at 1633 cm-1 in the spectrum of PP2 and this confirmed the presence of carbon-carbon double bond of itaconic acid [14].
The purified pre-polymers were characterized by 1H NMR and Figures 3a and 3b showed the 1H NMR spectra of the pre-polymers PP1 and PP2 respectively. A proposed structural formula for the resulting copolyesters (Figures 1a and 1b) showed the correlation between the different structural components and the observed chemical shifts of the pre-polymers. The multiple peaks around 2.8 ppm, and 4.1 ppm [5, 6, 8] were attributed to the protons in –CH2– group and alcoholic –OH group from citric acid. The peak at around 3.4 ppm could be due to the proton signal of –OCH2CH2- from 1, 12-dodecanediol [6]. The peaks at 1.3 and 1.7 ppm were attributed to –CH2- protons of sebacic acid and 1, 12 dodecanediol with the peaks overlapping in PP1. The chemical shift value for –CO-CH2- group of sebacic acid was found

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