Structure and Transport Properties of Highly Resilient Networks

Polymer networks are critically important for numerous applications including soft biomaterials, adhesives, coatings, elastomers, and gel-based materials for energy storage. One long-standing challenge these materials present lies in understanding the role of network defects, such as dangling ends and loops, developed during cross-linking. These defects can negatively impact the physical, mechanical, and transport properties of the gel. Here we report the structure and transport properties of chemically cross-linked poly(ethylene glycol) (PEG) and PEG-PDMS gels formed through a unique cross-linking scheme designed to minimize defects in the network. Small-angle neutron scattering (SANS) was utilized to investigate the network structures of gels in both D₂O and d-DMF. The highly resilient mechanical properties of these systems, results from SANS, and diffusivity of small molecules in these gels all suggest that the gels have a low incidence of defects.