Snapp Peter, Cho Chullhee, Lee Dongwon, Haque Md Farhadul, Nam SungWoo, Park Cheol
Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, 27695, USA.
Adv Mater. 2020 Oct;32(43):e2004607. doi: 10.1002/adma.202004607. Epub 2020 Sep 21.
Boron nitride nanotubes (BNNT) uniformly dispersed in stretchable materials, such as poly(dimethylsiloxane) (PDMS), could create the next generation of composites with augmented mechanical, thermal, and piezoelectric characteristics. This work reports tunable piezoelectricity of multifunctional BNNT/PDMS stretchable composites prepared via co-solvent blending with tetrahydrofuran (THF) to disperse BNNTs in PDMS while avoiding sonication or functionalization. The resultant stretchable BNNT/PDMS composites demonstrate augmented Young's modulus (200% increase at 9 wt% BNNT) and thermal conductivity (120% increase at 9 wt% BNNT) without losing stretchability. Furthermore, BNNT/PDMS composites demonstrate piezoelectric responses that are linearly proportional to BNNT wt%, achieving a piezoelectric constant (|d |) of 18 pmV at 9 wt% BNNT without poling, which is competitive with commercial piezoelectric polymers. Uniquely, BNNT/PDMS accommodates tensile strains up to 60% without plastic deformation by aligning BNNTs, which enhances the composites' piezoelectric response approximately five times. Finally, the combined stretchable and piezoelectric nature of the composite was exploited to produce a vibration sensor sensitive to low-frequency (≈1 kHz) excitation. This is the first demonstration of multifunctional, stretchable BNNT/PDMS composites with enhanced mechanical strength and thermal conductivity and furthermore tunable piezoelectric response by varying BNNT wt% and applied strain, permitting applications in soft actuators and vibration sensors.
均匀分散在可拉伸材料（如聚二甲基硅氧烷（PDMS））中的氮化硼纳米管（BNNT），可以制造出具有增强机械、热和压电特性的下一代复合材料。这项工作报道了通过与四氢呋喃（THF）共溶剂共混制备的多功能BNNT/PDMS可拉伸复合材料的可调谐压电性，该方法可在不进行超声处理或功能化的情况下将BNNT分散在PDMS中。所得的可拉伸BNNT/PDMS复合材料显示出增强的杨氏模量（在9 wt% BNNT时增加200%）和热导率（在9 wt% BNNT时增加120%），同时不损失拉伸性。此外，BNNT/PDMS复合材料表现出与BNNT重量百分比成线性比例的压电响应，在9 wt% BNNT时未经极化即可实现18 pmV的压电常数（|d|），这与商业压电聚合物具有竞争力。独特的是，BNNT/PDMS通过排列BNNT可承受高达60%的拉伸应变而不发生塑性变形，这使复合材料的压电响应增强了约五倍。最后，利用复合材料的可拉伸和压电特性相结合，制造出对低频（≈1 kHz）激励敏感的振动传感器。这是首次展示具有增强机械强度和热导率以及通过改变BNNT重量百分比和施加应变实现可调谐压电响应的多功能、可拉伸BNNT/PDMS复合材料，使其可应用于软致动器和振动传感器。
