Continuous Twisted Nano-fibrous Yarns for Smart Piezo-Textiles

服装可能是继食物之后最常见的人类必需品，而纺织品是人类生活的一个基本方面，几十年来一直没有改变过他们的“被动”形式。目前的面料是由尼龙和棉花等被动材料制成的。该项目的目标是研究利用纳米智能(压电)聚合物纱线实现可控、可重复生产功能智能织物的科学基础，并将其与传统织物集成。智能纺织品的应用可能包括发电和储存、个人防护、体育、时尚、通信、医疗和生理监测应用以及物联网。特别是，智能压电织物可用于机械能量收集、热释电效应热能收集、铁电应用、压力和力传感器、运动检测和超声波传感。智能面料将能够对不同的物理刺激(机械、电气、热等)做出反应。并因此可以与他们的环境交互(感知、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、可编织和可缝合)压电丝的加工和放大制造能力；显著提高其机电转换效率；以及将压电丝与传统和导电线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项目增加纳米技术-STEM的多样性。这些学生将接受纳米技术研究方面的培训，特别是由压电纳米纤维制成的智能织物。在这个项目中，提出了一种基于连续电纺的制造工艺，使加捻纱能够连续生产。压电聚合物用于智能织物应用的一个主要障碍是，与压电陶瓷(~50%)相比，压电聚合物的机电转换效率(~2%)较低，这是固有的脆性，不适合智能织物应用。这项研究的科学成果将是热机械加工、结晶度百分比、微晶取向与压电纳米纤维和扭束的弹性和压电性能之间的相互关系。通过制造和加工步骤并结合计算分析，该项目将生产出具有显著提高的压电效率的聚合物纱线。这将通过热机械处理(热处理和拉伸)来实现，旨在控制压电聚合物纤维的形态(结晶度百分比和晶体取向)，从而控制性能(弹性和压电性能)以及在各种外部负载下的性能和输出功率。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.