Cascaded Step-Growth Polymerization for Functional Polyamides with Diverse Architectures and Stimuli Responsive Characteristics.

Thiolactone ring opening and disulfide-thiol exchange were rationally coupled to develop a cascaded step-growth polymerization methodology for preparation of degradable polyamides. A variety of functionalities can be readily incorporated on to these polyamides by pre- and post-polymerization reactions. The polymers can be degraded into small molecules in the presence of biologically relevant reducing agents via backbone degradation, the kinetics of which is tunable. In addition to the redox-based chemical stimulus, the polyamides are also sensitive to light and enzymes, thus exhibiting concurrent sensitivity to chemical, physical, and biological stimuli.