Continuous Twisted Nano-fibrous Yarns for Smart Piezo-Textiles

服装，食物之后，也许是最常见的人类必需品，纺织品是人类生活的基本方面，几十年来一直没有改变其“被动”形式。目前的织物是由被动材料，如尼龙和棉花。该项目的目标是研究科学基础，以实现可控的，可再生的生产功能性智能织物从纳米尺寸的智能（压电）聚合物纱线，及其与传统织物的整合。智能纺织品的应用可以包括发电和存储、个人防护、体育、时尚、通信、医疗和生理监测应用以及物联网。特别地，智能压电织物可以用于机械能收集、用于通过热电效应的热能收集、用于铁电应用、作为压力和力传感器、用于运动检测以及用于超声波感测。智能织物将有能力对不同的物理刺激（机械，电，热等）作出反应。并且因此可以与它们的环境交互（感测、响应、通信和/或适应）。该项目将解决以下挑战，以实现智能压电聚合物织物：开发连续（可编织，可折叠和可缝合）压电纱线的加工和放大制造能力;显著提高其机电转换效率;以及压电纱线与传统和导电纱线的集成和包装的设计策略。该项目的教育目标是通过高中生暑期课程增加纳米技术-STEM的多样性。这些学生将接受纳米技术研究的培训，特别是由压电纳米纤维制成的智能织物。在该项目中，提出了一种基于连续静电纺丝的制造工艺，该工艺能够连续生产加捻纱线。压电聚合物用于智能织物应用的主要障碍是与压电陶瓷（~50%）相比压电聚合物的机电转换效率低（~2%），压电陶瓷固有地易碎并且不适合于智能织物应用。这项研究的科学成果将是热机械加工，结晶度的百分比，和取向的微晶和压电纳米纤维和扭曲束的弹性和压电性能的相互关系。通过结合计算分析的制造和加工步骤，该项目将生产具有显著增强的压电效率的聚合物纱线。这将通过热机械加工来实现（热退火和拉伸），旨在控制形态（结晶度的百分比和微晶的取向），因此，（弹性和压电性能）该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准。

Clothing, after food, is perhaps the most common human essential, and textiles are a basic aspect of human life that has not changed from their “passive” form for many decades. Current fabrics are made of passive materials such as nylon and cotton. The goal of this project is to investigate scientific foundations to realize controllable, and reproducible production of functional smart fabrics from nano-sized smart (piezoelectric) polymer yarns, and their integration with conventional fabrics. Applications of smart textiles could include power generation and storage, personal protection, sports, fashion, communication, medical and physiological monitoring applications, and the internet of things. In particular, smart piezoelectric fabrics can be used for mechanical energy harvesting, for thermal energy harvesting through the pyroelectric effect, for ferroelectric applications, as pressure and force sensors, for motion detection, and for ultrasonic sensing. Smart fabrics will have the ability to react to different physical stimuli (mechanical, electrical, thermal, etc.) and as such can interact (sense, respond, communicate, and/or adapt) with their environment. This project will address the following challenges to realize smart piezoelectric polymer fabrics: development of processing and scale-up fabrication capabilities for production of continuous (weavable, knittable, and sewable) piezoelectric yarns; significant improvement in their electromechanical conversion efficiency; and design strategies for integration and packaging of piezoelectric yarns with conventional and conductive threads. The educational objective of the project is focused on increasing the diversity in nanotechnology-STEM through summer programs for high school students. These students will be trained on nanotechnology research, in particular smart fabrics made of piezo nanofibers. In this project, a manufacturing process based on continuous electrospinning is proposed that enables continuous production of twisted yarns. A major obstacle in the utilization of piezoelectric polymers for smart fabric applications has been the low electromechanical conversion efficiency of piezo polymers (~2%) compared to the piezo ceramics (~50%), which are inherently brittle and not suitable for smart fabric applications. The scientific outcomes of this research will be the inter-relation of thermomechanical processing, percentage of crystallinity, and orientation of crystallites and elastic and piezoelectric properties of the piezoelectric nanofibers and twisted bundles. Through fabrication and processing steps combined with computational analysis, the project will produce polymer yarns with significantly enhanced piezoelectric efficiency. This will be achieved through thermomechanical processing (thermal annealing, and drawing) designed to control the morphology (percentage of crystallinity, and orientation of crystallites), and hence properties (elastic and piezoelectric properties) and performance and output power under various external loads of piezoelectric polymer fibers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.