Estane is a commercial poly(ester urethane), and is a multiblock copolymer obtained by the polymerization of 4,4’-diphenylmethane diisocyanate (MDI) chain-extended with 1,4-butanediol (BDO) as the rigid hard segment and polybutylene adipate (PBA) as the flexible soft segment, as shwon in Figure 1. With these two segments, the polymer exhibits good abrasion resistance, high elongation, and low temperature flexibility. It can be processed by means of solution coating, extrusion, and melt coating. Therefore, the polymer is widely used as adhesive for inks and lacquers, fabric coating, binder for magnetic media and composite material formation. Recent years, poly(ester urethane) gains more and more interests in biomedical applications and biomaterial fields because of its elasticity, sufficient mechanical strength, and biodegradability. It is essential to understand these properties change as the material ages and to identify the chemical degradation mechanisms. Over the years, numerous studies have been conducted and have determined several mechanisms of degrading the poly(ester urethane) depending on exposure environments, such as hydrolysis and non-hydrolysis reactions caused by the presence of moisture or/and oxidant. To accelerate the aging processes in experiments, the polymers are often aged under elevated temperatures resulting in chain scissions and branched structures, which make the identification of the chemical structures of the degraded products challenging.<br/>In this contribution, we systematically characterized a set of naturally aged Estanes up to 35 years with the molecular weight ranging from 135 – 20 kDa. The combination of size exclusion chromatography with UV/vis, viscometer, MALS detectors, FTIR and Raman spectroscopies, and thermal characterizations allows us to fully analyze these degraded polymers, leading to new information about (i) chemical structures of oligomer and polymer fractions, (ii) their spectroscopes, and (iii) their thermal properties.

Investigation of poly(ester urethane) degradations

2019 Spring National Meeting

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