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

该小企业创新研究二期项目旨在为水泥混凝土路面、沥青混凝土路面、桥面等接缝和裂缝的密封提供一种价格合理的密封胶。在交通基础设施中，为了在温度上升/下降时允许结构元件由于线性热膨胀/收缩而移动，故意建造了接缝。裂缝是路面上常见的破坏模式，如果密封不当，可能会导致混凝土的水损伤和破裂。密封裂缝和接缝是保持或延长结构元件使用寿命的常用做法。目前使用的各类密封胶的年市场价值约为61亿元。不幸的是，许多这些密封剂不能正常工作，在延长使用寿命方面是无效的。在这个项目中，将开发一种智能密封胶，它在冷却时膨胀，在加热时收缩，与混凝土的热特性相反。该产品将解决行业中由连接/开裂结构元件的热运动引起的重大问题。预计该产品将在5年内占有约0.8%的市场份额，这有助于满足对更持久、更可靠的基础设施的需求。该项目的智力价值在于智能密封胶技术的开发和验证。接缝破坏的根本原因是大多数密封胶的热膨胀特性与混凝土相似，即遇冷收缩，遇热膨胀。这种行为与为了避免密封胶和混凝土之间的热分离而对密封胶的要求是相反的。不幸的是，很少有材料能够以经济有效的方式满足这一要求，同时保持其他所需的物理特性（如可变形性）。该二期项目将通过使用基于双向形状记忆聚合物（2W-SMP）的密封胶来解决长达一个世纪的问题，从而解决根本原因。在一期项目可行性研究的基础上，二期项目将重点进一步改进基于2W-SMP的密封胶，用于密封路面接缝或裂缝，并通过第三方实验室规模的测试，以及在湿热环境和极寒地区的全面现场验证。技术成果将包括实验室规模的验证，现场水平的性能和验证，以及这种新型智能材料的施工协议，为房主和运输机构的采用奠定坚实的基础。

This Small Business Innovation Research Phase II project aims to provide an affordable sealant for sealing joints and cracks in cement concrete pavement, asphalt concrete pavement, bridge deck, etc. In transportation infrastructure, joints are intentionally constructed in order to allow movement of the structural elements due to linear thermal expansion/contraction when temperature rises/drops. Cracks are a common failure mode in pavement, and if not properly sealed, can cause water damage and rupture of the concrete. Sealing cracks and joints is a common practice to maintain or extend the service life of structural elements. Various types of sealants are currently used with an annual market value of about $6.1 billion. Unfortunately, many of these sealants fail to work properly and are ineffective in extending service life. In this project, a smart sealant will be developed that expands upon cooling and contracts upon heating, a thermal characteristic opposite to that of concrete. The product will address a significant problem in the industry arising from thermal movement of joined/cracked structural elements. It is expected that the product will have about 0.8% market share in 5 years helping with the need for longer lasting and more reliable infrastructure.The intellectual merit of this project lies in the development and validation of a smart sealant technology. The root cause for joint failure is that the thermal expansion characteristics of most sealants is similar to that of concrete, i.e., contraction upon cooling and expansion upon heating. This behavior is contrary to what is required of sealants in order to avoid thermally induced separation between the sealant and the concrete. Unfortunately, few materials can fulfill this requirement in a cost effective way while maintaining other desired physical properties (such as, deformability). This Phase II project will solve the century-long problem through the use of a two-way shape memory polymer (2W-SMP) based sealant that addresses the root cause. Building upon the feasibility study of the Phase I project, the Phase II project will focus on further improving the 2W-SMP based sealant for sealing joints or cracks in pavement, and validate the product through third-party lab-scale testing, and full-scale field-level verification in both hot and humid environment and extremely cold regions. Technical outcome will include lab-scale validation, field level performance and verification, and construction protocols for this new smart material, laying a solid foundation for adoption by home owners and transportation agencies.