SBIR Phase II: Injection-molded Thermoset Shape-memory Polymers with Enhanced Acoustic Properties

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This Small Business Innovation Research (SBIR) Phase II project supports the development of a unique manufacturing method to produce novel shape memory polymers in complex shapes. These smart materials can "remember" and reform to a set shape upon an external stimulus. This continuous manufacturing process is vastly more efficient than the current state-of-the-art methods, enabling many low cost applications of shape memory polymers. This project will develop shape memory polymer earplugs that are heat activated by the user's ear and continuously adapt and self-adjust to custom fit any size ear canal. Current material solutions for earplugs suffer from several drawbacks, including an inability to control the force exerted by the earplug upon sensitive inner ear regions that cause pain over time. This effort will address the technical challenges of scaling up the low cost manufacturing process and establish formulations that will enable optimization of its acoustic performance. Human subject testing will be conducted to subjectively validate comfort and objectively validate attenuation with very differently sized ear canals. If successful, this project will yield a device with optimized acoustic properties and comfort ready for first commercial sale.The broader/commercial impact of this project is the impact of a mass-manufactured shape memory polymer device. Due to their desired properties, shape memory polymers are increasingly used in biomedical applications, but their broader adoption into mass markets has been limited by cost and geometry constraints. If successful, this project will establish a novel manufacturing process that, through modified traditional plastics processing techniques, can mass manufacture a new class of polymers. Thus, the broad impact of this project is twofold: it will establish the first links between sound attenuation and crosslinker density in shape memory polymer earpieces, and it will lay the groundwork for future low cost shape memory devices of complex geometries. Better occlusion and more comfortable earplugs are expected to enable higher usage of protective hearing devices in loud industrial settings. This in turn addresses the growing problem of noise-induced hearing loss in the industrial sector, which according to OSHA, is the number one occupational disease in the US today. In addition, shape memory earplugs may benefit other users including musicians, professional athletes and children with autism. This technology can also be adapted to similar devices including cell phone headsets, Bluetooth audio devices, and hearing aids.