@article {47177,
	title = {Highly flexible mechanical energy harvester based on nylon 11 ferroelectric nanocomposites},
	journal = {ACS Applied Polymer Materials},
	volume = {1},
	year = {2019},
	month = {JUL},
	pages = {1998{\textendash}2005},
	type = {Article},
	abstract = {<p>We report here a flexible piezoelectric energy harvester using castor-oil-derived nylon 11 and biomass-derived cellulose nanocrystals (CNC). Using a simple solution casting process, we were able to fabricate flexible large area nylon 11 and composite films. Neat nylon 11 films crystallized predominantly in the α- phase. Incorporation of CNC at a low concentration of 2{\textendash}5 wt \% resulted in almost complete transition of α-phase to polar γ-phase, which could be attributed to strong hydrogen bonding interactions between CNC and amide groups in nylon 11. This remarkable shift in crystallization behavior also led to enhanced piezoelectric performance. We also found that the addition of 5 wt \% glycerol (on the dry weight of nylon 11 or composite) enhanced the flexibility of the film. Energy harvesting devices made from 5 wt \% nylon 11/CNC films showed about 2.6 times higher output voltage as compared to neat nylon 11 devices under similar impact conditions, and the effect was durable over 800 cycles. These devices were also used to charge a 10 μF polarized capacitor, and we found that the 5 wt \% nylon 11/CNC devices charged up to 3.78 V in 90 s, which is 2.8 times higher than nylon 11 devices. To the best of our knowledge, this is the first report on nylon 11 nanocomposites, where cellulose nanocrystals have been used to enhance the electroactive γ phase in nylon 11 and yield such high piezoelectric performance.</p>
},
	author = {Ram, Farsa and Radhakrishnan, Sithara and Ambone, Tushar and Shanmuganathan, Kadhiravan}
}
@article {47353,
	title = {Highly compressible ceramic/polymer aerogel-based piezoelectric nanogenerators with enhanced mechanical energy harvesting property},
	journal = {Ceramics International},
	volume = {47},
	year = {2021},
	month = {JUN },
	pages = {15750-15758},
	type = {Article},
	abstract = {<p>Ceramic piezoelectric materials have orders of magnitude higher piezoelectric coefficients compared to polymers. However, their brittleness precludes imposition of large strains in mechanical energy harvesting applications. We report here that ice templating affords low bulk modulus lead-free aerogel piezoelectric nanogenerators (PENG) with unprecedented combination of flexibility and high piezoelectric response (voltage and power density). A modified ice templating protocol was used to fabricate piezoelectric nanocomposites of surface modified BaTiO3 (BTO) nanoparticles in crosslinked polyethylene imine. This protocol allowed incorporating a significantly high fraction of BTO particles (up to 83 wt \%) in the aerogel, while retaining remarkably high compressibility and elastic recovery up to 80\% strain. The output voltage, at an applied compressive force of 20 N (100 kPa), increased with BTO loading and a maximum output voltage of 11.6 V and power density of 7.22 ?W/cm2 (49.79 ?W/cm3) was obtained for PENG aerogels containing 83 wt\% BTO, which is orders of magnitude higher than previously reported values for foam-based piezoelectric energy harvesters. The BTO/PEI PENGs also showed cyclic stability over 900 cycles of deformation. PENGs with higher porosity showed better elastic recovery and piezoelectric properties than lower porosity and higher BTO content aerogels. To the best of our knowledge, this is the first report to demonstrate the piezoelectric properties of high ceramic content aerogels having very high compressibility and elastic recovery.</p>},
	keywords = {Ceramic polymer aerogels, energy harvesting, ice templating, piezoelectric},
	issn = {0272-8842},
	doi = {10.1016/j.ceramint.2021.02.147},
	author = {Ram, Farsa and Suresh, Karthika and Torris, Arun and Kumaraswamy, Guruswamy and Shanmuganathan, Kadhiravan}
}
