(447f) Well-Defined Polymeric Structures Based on Novel Degradable Cross-Linkers

Non-linear, branched polymers have attracted significant attention due to their unique structure and properties. Of particular interest to our group are polymer networks (soft materials – gels) whose branching points are cleavable under appropriate chemical or physical stimuli. The properties of polymer networks containing degradable crosslinks undergo dramatic changes upon degradation and branch removal, thus rendering such polymers ideal in biomedical and electronics applications (as hydrolyzable biomaterials for controlled drug delivery and tissue engineering, and thermolyzable polymers for removal and re-attachment of components, respectively). The investigation of these changes for chemically different branching points and under various degradation conditions constitutes a field of active research.

Our work is the first to address the synthesis via a “controlled” polymerization method, group transfer polymerization (GTP), characterization and degradation of polymer networks and star polymers based on cross-linkers degradable under different conditions. The novelty of our work lies on: (1) the use of newly synthesized novel degradable cross-linkers, bearing different labile groups; and (2) the control of the architecture, molecular weight and polydispersity of the synthesized polymers – neat cross-linker networks, randomly cross-linked networks, and cross-linked star polymer model networks and their constituent star polymer nanoobjects – and their degradation products.

The successful synthesis and degradation (hydrolysis or thermolysis) of such well-defined polymer networks was established with a variety of experimental techniques including Gel Permeation Chromatography (GPC), Nuclear Magnetic Resonance (NMR) spectroscopy, Dynamic and Static Light Scattering (DLS and SLS), and Thermogravimetric Analysis (TGA). Structure-property relationships were established.