Elastic Polyamide Biomaterials With Stereochemically Adjustable Mechanical Properties and Shape Memory

Biocompatible polymers are widely used in tissue engineering and biomedical devices. However, few biomaterials are suitable for long-term implant use, and these examples are usually limited in nature, may be difficult to handle, and do not respond to external stimuli.

Here, we explored the addition of dimercaptan to disulfide amide monomers to produce stereocontrolled unsaturated polyamides with strong thermodynamic properties. The presence of amide and unsaturated parts along the backbone gives the material unique properties, namely shape memory behavior and stereochemically dependent thermodynamic properties. In addition, mercaptan - acetylene polyamide is amorphous, has good optical transparency, and also exhibits elasticity above the glass transition temperature. These properties make polymers unique in the synthesis of polyamides, such as nylon, which is semi-crystalline (when stretched) and has no shape memory behavior, which limits their usefulness as the medical device community begins to embrace minimally invasive designs. All the materials are cytocompatible, and preliminary in vivo experiments have shown good biocompatibility, underscoring their potential as multifunctional biomaterials. Through rational utilization of reaction conditions, the stereochemistry of olefin is modulated between 35-82% cis-content. Stereochemistry determines the tensile strength, modulus and glass transition properties of the whole material. By polymerizing various commercially available dimercaptan with dipropanolamide monomers, further materials with a wider range of thermal and mechanical properties can be obtained.