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

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.