Polyurethane elastomer with stable mechanical performance during biodegradation: Material design and constitutive modeling

Abstract

The growing demand for biodegradable elastomers necessitates innovative designs achieving controllable degradation rates while maintaining stable mechanical performance. This work presents a novel polyurethane elastomer (PUE) with dual degradation pathways, including selective degradation of soft and hard domain. This design offers enhanced control over mechanical performance, realizing only 15 % reduction in failure stretch at ∼50 % degradation and less than 2 % loss in initial modulus at ∼85 % degradation. Next, we propose a novel micro-mechanical model incorporating domain-specific degradation mechanisms to theoretically predict the degradation mechanical performance of PUE. A modified generalized series configuration captures domain interactions by linking free joint chains in soft domain with extensible hard segment clusters. Specially, degradation degree is defined as an internal variable characterizing the evolution of microscopic parameters, including Kuhn segments number, chain density, and cluster density. Thus, the macroscopic changes in modulus and failure stretch can be directly correlated to the microscopic degradation-induced chain scission, cluster breakage, and interactions like chain release and cluster detachment. The model successfully predicts the tensile behavior of PUE under selective degradation. Further theoretical analysis reveals that robust clusters play a pivotal role in maintaining mechanical stability and their continuously preserved structural integrity effectively minimizes modulus reduction caused by chain scission and cluster breakage. This work provides theoretical insights and a practical foundation for the rational design and application of biodegradable PUEs.