Mechanical Characterization and Determination of Self-Healing Efficiency for polyurea-PDMS Polymers via Tensile Testing

The intrinsic self-healing efficiency of polydimethylsiloxane (PDMS) based polymers is extensively evaluated through tensile testing. Our research group has synthesized three novel, intrinsically self-healing polymers composed of bis (aminopropyl) terminated PDMS units reacted with diisocynates to form urea linkages. By altering the molecular weight range of the aminopropyl terminated PDMS starting material, polymers that yield different mechanical properties are created. The self-healing efficiencies and modulus of these novel polymers are evaluated via tensile testing to evaluate their overall strength and flexibility. Tensile testing involves stretching the polymer until it fractures, recording the force (N), time (s), and extension (mm) which can be used to calculate the stress and strain to determine the tensile strength and elastic modulus. Samples of the polymer are tested before and after being damaged to determine the percentage healing efficiency. The study identifies how molecular weight of the PDMS influences the self-healing capability and the mechanical properties of the polymer. This data is crucial for understanding the relationship between polymer structure and self-healing efficiency. Furthermore, this systematic investigation into the balance of IMFs and molecular mobility as a function of chain length gives insight towards the design of other self-healing polymers with different functional groups and mechanical properties.