Influence of amine chain extenders on morphology and performances of poly(dimethylsiloxane) based poly(urea‐urethane) elastomers

Abstract The structure, morphology, and performance of polyurethanes are greatly influenced by the structure of chain extenders. In this study, two types of amine chain extenders, 1,3‐bis(3‐aminopropyl)‐1,1,3,3‐tetramethyldisiloxane (BAPD) and isophorone diamine (IPDA), were utilized in the synthesis of poly(dimethylsiloxane) (PDMS)‐based poly(urea‐urethane) elastomers (PDMS‐PUUs). The mechanical properties, morphology, and in vitro oxidative stability of the as‐prepared elastomers were controlled by altering the ratio of BAPD and IPDA. The results indicate that the overall phase mixing of PDMS‐PUUs improves after incorporating of BAPD into the hard segments. The hard segment, composed of IPDA with a rigid structure, plays a crucial role in maintaining the essential mechanical properties of the PDMS‐PUUs. Furthermore, PDMS‐PUUs based on mixed chain extenders exhibit relatively high boundary diffuseness and boundary thickness. Especially, the PDMS‐PUU sample synthesized from BAPD and IPDA with a molar ratio of 1/1 features the highest boundary diffuseness (0.094) and boundary thickness (0.395 nm), consequently displaying some remarkable properties, including enhanced cyclic tensile properties, superior strain recovery (92.6%), a low modulus (8.6 MPa), and high tensile strength (20.3 MPa). PDMS‐PUUs also exhibit good oxidative stability and biocompatibility, implying that the as‐prepared PDMS‐PUUs are proven to be biostable and capable of long‐term implantation.