SBIR Phase I: Smart Two-Way Shape Memory Polymer Based Sealant

This Small Business Innovation Research Phase I project aims to provide an affordable sealant for sealing expansion joints and cracks in concrete pavement, bridge deck, etc. In transportation infrastructure, expansion joints are intentionally constructed in order to allow movement of the structural elements due to linear thermal expansion when temperature rises. In addition, cracks are a common failure mode in pavement. If they are not properly sealed, water penetration will damage the surface layer and the layers beneath, and entrapped debris will cause rupture of the concrete wall. Therefore, sealing cracks and joints is a common practice to maintain or extend the structure service life. Various types of sealants have been used with an annual market value about $6.1 billion. Unfortunately, many sealants cannot properly seal cracks and joints, and/or last long, requiring frequent replacement or resealing. In this project, a smart sealant that expands upon cooling and contracts upon heating, which is thermally opposite to concrete, will be developed to counteract thermal movement of the joined structural elements. The intellectual merit of this project lies in the feasibility of a smart sealant technology. The primary reason for joint failure is that most sealants behave similar to concrete, i.e., they contract upon cooling and expand upon heating. This thermal behavior is contrary to the requirement for sealants. The objective of this project is to design, synthesize, characterize, and evaluate a cost-effective two-way shape memory polymer based sealant for sealing expansion joints or cracks in concrete pavement or bridge deck, which will expand upon cooling and contract upon heating. It will have the required mechanical properties and durability to survive the repeated traffic load and outdoor environment. The success of the project can have beneficial impact not only on the transportation infrastructure but also other structures such as driveways, parking lots, dams, harbors, buildings, swimming pools, etc.