@article {44110, title = {Fire-retardant, self-extinguishing inorganic/polymer composite memory foams}, journal = {ACS Applied Materials \& Interfaces}, volume = {9}, year = {2017}, month = {DEC}, pages = {44864-44872}, type = {Article}, abstract = {Polymeric foams used in furniture and automotive and aircraft seating applications rely on the incorporation of environmentally hazardous fire-retardant additives to meet fire safety norms. This has occasioned significant interest in novel approaches to the elimination of fire-retardant additives. Foams based on polymer nano composites or based on fire-retardant coatings show compromised mechanical performance and require additional processing steps. Here, we demonstrate a one-step preparation of a fire-retardant ice-templated inorganic/polymer hybrid that does not incorporate fire-retardant additives. The hybrid foams exhibit excellent mechanical properties. They are elastic to large compressional strain, despite the high inorganic content. They also exhibit tunable mechanical recovery, including viscoelastic "memory". These hybrid foams are prepared using ice-templating that relies on a green solvent, water, porogen. Because these foams are predominantly comprised of inorganic components, they exhibit exceptional fire retardance in torch burn tests and are self-extinguishing. After being subjected to a flame, the foam retains its porous structure and does not drip or collapse. In micro-combustion calorimetry, the hybrid foams show a peak heat release rate that is only 25\% that of a commercial fire-retardant polyurethanes. Finally, we demonstrate that we can use ice-templating to prepare hybrid foams with different inorganic colloids, including cheap commercial materials. We also demonstrate that ice-templating is amenable to scale up, without loss of mechanical performance or fire-retardant properties.}, doi = {10.1021/acsami.7b16808}, author = {Chatterjee, Soumyajyoti and Shanmuganathan, Kadhiravan and Kumaraswamy, Guruswamy} } @article {44616, title = {Flexible composite mechanical energy harvester from a ferroelectric organoamino phosphonium salt}, journal = {Angewandte Chemie-International Edition}, volume = {57}, year = {2018}, month = {JUL}, pages = {9054-9058}, abstract = {

A new binary organic salt diphenyl diisopropylamino phosphonium hexaflurophosphate (DPDPPF6) was shown to exhibit a good ferroelectric response and employed for mechanical energy harvesting application. The phosphonium salt crystallizes in the monoclinic noncentrosymmetric space group Cc and exhibits an H-bonded 1D chain structure due to N-HF interactions. Ferroelectric measurements on the single crystals of DPDPPF6 gave a well-saturated rectangular hysteresis loop with a remnant (P-r) polarization value of 6Ccm(-2). Further, composite devices based on polydimethylsiloxane (PDMS) films for various weight percentages (3, 5, 7, 10 and 20wt\%) of DPDPPF6 were prepared and examined for power generation by using an impact test setup. A maximum output peak-to-peak voltage (V-PP) of 8.5V and an output peak-to-peak current (I-PP) of 0.5A was obtained for the non-poled composite film with 10wt\% of DPDPPF6. These results show the efficacy of organic ferroelectric substances as potential micropower generators.

}, keywords = {binary phosphonium salts, energy conversion, ferroelectricity, hydrogen bonding, polymer composites}, issn = {1433-7851}, doi = {10.1002/anie.201805479}, author = {Vijayakanth, Thangavel and Srivastava, Anant Kumar and Ram, Farsa and Kulkarni, Priyangi and Shanmuganathan, Kadhiravan and Praveenkumar, Balu and Boomishankar, Ramamoorthy} } @article {44652, title = {Fluorinated nanocellulose-reinforced all-organic flexible ferroelectric nanocomposites for energy generation}, journal = {Journal of Physical Chemistry C}, volume = {122}, year = {2018}, month = {JUL}, pages = {16540-16549}, abstract = {

We report here enhanced ferroelectric crystal formation and energy generation properties of polyvinylidene fluoride (PVDF) in the presence of surface-modified crystalline nanocellulose. Incorporation of only 2-5 wt \% fluorinated nanocellulose (FNC) in PVDF has been found to significantly induce polar beta/gamma-phase crystallization as compared to the addition of unmodified nanocellulose (carboxylated nanocellulose). A device made up of electrically poled PVDF/FNC composite films yielded 2 orders of magnitude higher voltage output than neat PVDF in vibrational energy harvesting. This remarkable increase in energy generation properties of PVDF at such a low loading of an organic natural biopolymer could be attributed to the tailored surface chemistry of nanocellulose, facilitating strong interfacial interactions between PVDF and FNC. Interestingly, energy harvesting devices fabricated from PVDF/FNC nanocomposites charged a 4.7 mu F capacitor at significantly faster rate and the accumulated voltage on capacitor was 3.8 times greater than neat PVDF. The fact that PVDF/FNC nanocomposites still retain a strain at break of 10-15\% and can charge a capacitor in few seconds suggests potential use of these nanocomposites as flexible energy harvesting materials at large strain conditions.

}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.8b03470}, author = {Ram, Farsa and Ambone, Tushar and Sharma, Aakash and Murugesan, Rajarathinam and Kajale, Deepak and Borkar, Vivek and Ali, Shaikh Faruque and Balu, Praveen Kumar and Kumaraswamy, Guruswamy and Shanmuganathan, Kadhiravan} } @article {44345, title = { Functionalized carbon nanotube reinforced polymer nanocomposite microcapsules with enhanced stiffness}, journal = {Colloids and Surfaces A-Physicochemical and Engineering Aspects}, volume = {550}, year = {2018}, month = {AUG}, pages = {82-89}, type = {Article}, abstract = {Microcapsules with tunable mechanical properties are highly desirable in pressure sensitive applications. We report here a facile approach to prepare polyurea/multiwall carbon nanotube (MWCNTs) nanocomposite microcapsules (MICs) with enhanced stiffness. A model compound dimethyl phthalate (DMP) was used as core material. MWCNTs were modified with reactive functional groups namely carboxyl (-COOH), amines (-NH2), and isocyanates (-NCO) to ensure a stronger interface between polymer wall and MWCNTs. Functionalization of MWCNTs was corroborated by Fourier transformed infrared spectroscopy (FTIR). Scanning electron microscopy (SEM) was employed to study the surface morphology of MICs. The presence of MWCNTs in the microcapsule wall was confirmed by transmission electron microscopy (TEM). MICs with functionalized MWCNTs show almost 100\% increase in stiffness with respect to pristine capsules. All MICs show 92-97 +/- 1\% encapsulation efficiency. The approach used in this paper can be broadly utilized to tune the mechanical properties of the microcapsules.}, doi = {10.1016/j.colsurfa.2018.04.028}, author = {Jagtap, Siddheshwar B. and Patil, Vishal D. and Suresh, Karthika and Ram, Farsa and Mohan, Muthu Subramanian and Rajput, Shatruhan S. and Patil, Shivprasad and Shukla, Parshuram G. and Shanmuganathan, Kadhiravan} } @article {47747, title = { Flexible energy harvester from an organic ferroelectric ammonium salt}, journal = {Chemistry-An Asian Journal}, volume = {16}, year = {2021}, month = {DEC }, pages = {4122-4129}, type = {Article}, abstract = {Organic ferroelectrics due to their low cost, easy preparation, light weight, high flexibility and phase stability are gaining tremendous attention in the field of portable electronics. In this work, we report the synthesis, structure and ferroelectric behavior of a two-component ammonium salt 2, containing a bulky [Bn(4-BrBn)NMe2](+) (Bn=benzyl and 4-BrBn=4-bromobenzyl) cation and tetrahedral (BF4)(-) anion. The structural analysis revealed the presence of rich non-classical C-H...F and C-H...Br interactions in this molecule that were quantified by Hirshfeld surface analysis. The polarization (P) vs. electric field (E) hysteresis loop measurements on 2 gave a remnant polarization (P-r) of 14.4 mu C cm(-2) at room temperature. Flexible polymer composites with various (5, 10, 15 and 20) weight percentages (wt\%) of 2 in thermoplastic polyurethane (TPU) were prepared and tested for mechanical energy harvesting applications. A notable peak-to-peak output voltage of 20 V, maximum current density of 1.1 mu A cm(-2) and power density of 21.1 mu W cm(-2) were recorded for the 15 wt\% 2-TPU composite device. Furthermore, the voltage output generated from this device was utilized to rapidly charge a 100 mu F capacitor, with stored energies and measured charges of 156 mu J and 121.6 mu C, respectively.}, keywords = {Dielectric, energy harvesting, ferroelectricity, organic composites, piezoelectric}, issn = {1861-4728}, doi = {10.1002/asia.202101128}, author = {Gupta, Rishabh and Sahoo, Supriya and Deswal, Swati and Kothavade, Premkumar and Dixit, Prashant and Zareba, Jan K. and Shanmuganathan, Kadhiravan and Boomishankar, Ramamoorthy} } @article {49140, title = { Ferroelectric aminophosphonium cyanoferrate with a large electrostrictive coefficient as a piezoelectric nanogenerator}, journal = {Angewandte Chemie-International Edition}, volume = {62}, year = {2023}, month = {JAN }, type = {Article}, abstract = {

Hybrid materials possessing piezo- and ferroelectric properties emerge as excellent alternatives to conventional piezoceramics due to their merits of facile synthesis, lightweight nature, ease of fabrication and mechanical flexibility. Inspired by the structural stability of aminophosphonium compounds, here we report the first A(3)BX(6) type cyanometallate [Ph-2((PrNH)-Pr-i)(2)P](3)[Fe(CN)(6)] (1), which shows a ferroelectric saturation polarization (P-s) of 3.71 mu C cm(-2). Compound 1 exhibits a high electrostrictive coefficient (Q(33)) of 0.73 m(4) C-2, far exceeding those of piezoceramics (0.034-0.096 m(4) C-2). Piezoresponse force microscopy (PFM) analysis demonstrates the polarization switching and domain structure of 1 further confirming its ferroelectric nature. Furthermore, thermoplastic polyurethane (TPU) polymer composite films of 1 were prepared and employed as piezoelectric nanogenerators. Notably, the 15 wt \% 1-TPU device gave a maximum output voltage of 13.57 V and a power density of 6.03 mu W cm(-2).

}, keywords = {Cyanometallates, energy conversion, H-bonding, hybrid composites, Phosphorus}, issn = {1433-7851}, doi = {10.1002/anie.202214984}, author = {Vijayakanth, Thangavel and Sahoo, Supriya and Kothavade, Premkumar and Sharma, Vijay Bhan and Kabra, Dinesh and Zareba, Jan K. K. and Shanmuganathan, Kadhiravan and Boomishankar, Ramamoorthy} }