Semiquantitative FTIR Analysis of the Crosslinking Density of Poly(ester amide)‐Based Thermoset Elastomers

Thermoset elastomers represent a class of polymers for a wide range of biomedical applications. Crosslinking density of thermoset elastomers is considered as an important parameter. In this study, semiquantitative Fourier transform infrared (FTIR) analysis is developed as a novel method to determine crosslinking density of poly (ester amide) thermoset elastomers. Poly(1,3-diamino-2-hydroxypropane-co-polyol sebacate) (APS) is an example of poly(ester amide) thermoset elastomer. Polyethylene glycol (PEG) has been recently incorporated into APS polymer structure to obtain novel PEGylated APS-based elastomers with tunable properties. The crosslinking densities of different APS and APS-co-PEG films are determined by the theory of rubber elasticity and FTIR. These results show that the intensity ratios between amide and carbonyl peak correlate well with the calculated crosslinking density from the elastic modulus. Thus, semiquantitative FTIR analysis offers a direct, facile, and less variable method to determine the crosslinking density and guide the consistent synthesis of poly(ester amide) thermoset elastomers.