@article {46304, title = {Sustained release insect repellent microcapsules using modified cellulose nanofibers (mCNF) as pickering emulsifier}, journal = {Colloids and Surfaces A-Physicochemical and Engineering Aspects}, volume = {582}, year = {2019}, month = {DEC }, pages = {Article Number:123883}, type = {Article}, abstract = {

We report here an approach to encapsulate N, N-diethyl-3-methylbenzamide (DEET), an insect repellent, through interfacial polycondensation using modified cellulose nanofiber (CNF) as pickering emulsifier. We found that stearic acid functionalized CNF (mCNF) can be used to form stable pickering emulsions (oil-in-oil and water-in-oil), and further encapsulate DEET using interfacial polycondensation with very high encapsulation efficiency of about 98\%. Another major advantage of this approach is that mCNF can act both as pickering emulsifier and also strengthen the barrier properties of microcapsules resulting in significant reduction in release rate of DEET. Interpretation of the release profiles using standard mathematical models proposed by Ritger-Peppas show a factor of three reduction in release rate constant for the microcapsules reinforced with mCNF.

}, keywords = {Cellulose nanofiber, Controlled release, Microcapsules, Nanocomposite, nanoparticle, Pickering emulsion}, issn = {0927-7757}, doi = {10.1016/j.colsurfa.2019.123883}, author = {Kadam, Sandip L. and Yadav, Prashant and Bhutkar, Siddhant and Patil, Vishal D. and Shukla, Parshuram G. and Shanmuganathan, Kadhiravan} } @article {46716, title = {Amidinato germylene-zinc complexes: synthesis, bonding, and reactivity}, journal = {Chemistry-An Asian Journal}, volume = {15}, year = {2020}, month = {OCT }, pages = {3116-3121}, type = {Article}, abstract = {

Despite the explosive growth of germylene compounds as ligands in transition metal complexes, there is a modicum of precedence for the germylene zinc complexes. In this work, the synthesis and characterization of new germylene zinc complexes [PhC(NtBu)(2)Ge{N(SiMe3)(2)}-\> ZnX2](2)(X= Br (2) and I (3)) supported by (benz)-amidinato germylene ligands are reported. The solid-state structures of2and3have been validated by single-crystal X-ray diffraction studies, which revealed the dimeric nature of the complexes, with distorted tetrahedral geometries around the Ge and Zn center. DFT calculations reveal that the Ge-Zn bonds in2and3are dative in nature. The reaction of2with elemental sulfur resulted in the first structurally characterized germathione stabilized ZnBr(2)complexes PhC(NtBu)(2)Ge(=S){N(SiMe3)(2)}-\> ZnBr2(5). Therefore, the Ge=S in5is in-between Ge-S single and Ge=S double bond length, owing to the coordination of a sulfur lone pair of electrons to ZnBr2.

}, keywords = {DFT, Germathione, Germylene, X-ray Structure, zinc}, issn = {1861-4728}, doi = {10.1002/asia.202000807, Early Access Date = SEP 2020}, author = {Yadav, Sandeep and Kumar, Rohit and Raj, K. Vipin and Yadav, Prashant and Vanka, Kumar and Sen, Sakya S.} } @article {46887, title = {Dual responsive cellulose microspheres with high solid-state fluorescence emission}, journal = {Colloids and Surfaces A-Physicochemical and Engineering Aspects}, volume = {591}, year = {2020}, month = {APR}, pages = {124510}, type = {Article}, abstract = {

Materials that respond to multiple stimuli such as magnetic field and light are attractive for security and medical diagnostic applications. One of the major challenges in dual functional microspheres is that the presence of magnetic nanoparticles can quench fluorescence emission. Also, there is a probability of solid-state quenching due to the proximity of the fluorophore. We report here a facile approach to prepare cellulose microspheres with high solid-state fluorescence using 40 \% tetrabutylammonium hydroxide (TBAH). The fluorescence quenching effect due to the presence of Fe3O4 nanoparticles and solid-state quenching due to aggregation of fluorophore was systematically investigated. Microspheres with the detectable magnetic response and fluorescence quantum yield as high as 0.57 (FMB 414) was obtained by optimizing the reaction conditions. Such a high quantum yield has not been reported before for dual stimuli-responsive fluorescent microspheres. The magnetic and fluorescent properties were found to be durable even after multiple washing cycles. These dual responsive cellulose microspheres can be added as security features to authenticate documents such as passports, degree certificates, currency notes, financial documents etc.

}, keywords = {Fluorescent, Magnetic, Microcrystalline cellulose, microspheres, Stimuli responsive microspheres, Tetrabutylammonium hydroxide}, issn = {0927-7757}, doi = {10.1016/j.colsurfa.2020.124510}, author = {Yadav, Prashant and Prajitha, K. P. and Dhaware, Vinita and Subramani, Mohan and Joy, Pattayil and Asha, S. K. and Shanmuganathan, Kadhiravan} } @article {48139, title = {Nanocellulose/melanin-based composites for energy, environment, and biological applications}, journal = {Journal of Materials Science}, volume = {57}, year = {2022}, month = {AUG}, pages = {14188-14216}, type = {Review}, abstract = {

Melanins, a class of brown-black pigments present in many natural sources, exhibit unique physical and chemical properties such as photoprotection, photoconductivity, metal ion chelation, free radical quenching, proton conductivity, and significant antimicrobial properties. These properties could be leveraged in various environmental and energy applications. However, their limited solubility makes them less amenable to processing. Over the last decade, there has been tremendous interest in developing synthetic analogs of melanin that are easy to dissolve and process. Nonetheless, melanins or their synthetic analogs cannot form mechanically robust free-standing films and fibers. This drawback could be partly circumvented by creating composites of melanin with nanocellulose, a nanomaterial derived from cellulosic biomass. Composites of melanins and nanocellulose offer an opportunity to utilize the functional aspects of melanin-like polymers in a mechanically stable nanocellulose network. This review attempts to capture the recent developments on this topic with special emphasis on technologically relevant applications.

}, issn = {0022-2461}, doi = {10.1007/s10853-022-07512-1}, author = {Ram, Farsa and Yadav, Prashant and Shanmuganathan, Kadhiravan} } @article {48790, title = {Luminescent 3D printed poly(lactic acid) nanocomposites with enhanced mechanical properties}, journal = {Polymer Engineering and Science}, volume = {63}, year = {2023}, month = {JUL}, pages = {2059-2072}, type = {Article}, abstract = {

The three-dimensional (3D) printing of functional composite materials has gained tremendous interest in recent years. Nevertheless, research on 3D printing of luminescent composite materials is very limited, and the mechanical properties of such 3D-printed composites are poor. Herein, we report the preparation and characterization of a poly(lactic acid) (PLA) composite that, when 3D printed, exhibits enhanced toughness and high solid-state fluorescence quantum yield. Incorporation of only 1 wt\% pyrene butyric acid modified cellulose nanofibers (PBA-m-CNF) and l0 wt\% thermoplastic polyurethane (TPU) into PLA led to 223\% increase in toughness and 21\% increase in tensile modulus of PLA. Scanning electron microscopy (SEM) and X-ray microcomputed tomography (mu-CT) analysis of the fractured cross-sections of 3D printed composites revealed a ductile failure mode. The PLA/PBA-m-CNF1/TPU10 3D printed composite also exhibited a high solid-state fluorescence quantum yield of 38.35\%. To the best of our knowledge, this is the first report to show both enhanced mechanical properties and high solid-state fluorescence emission for 3D printable PLA. Such functional PLA composites could have potential applications in the fabrication of complex-shaped sensors, optical light pipes, etc.

}, keywords = {3D printing, Composite, fluorescence, Nanocellulose, poly(lactic acid), toughness}, issn = {0032-3888}, doi = {10.1002/pen.26345}, author = {Kothavade, Premkumar Anil and Yadav, Prashant and Nidhankar, Aakash D. and Torris, Arun and Pol, Harshawardhan and Kafi, Abdullah and Bateman, Stuart and Sukumaran, Santosh Babu and Shanmuganathan, Kadhiravan} } @article {49094, title = {Enhancing the crystallization kinetics and mechanical properties of poly(lactic acid) blends for 3D printing application}, journal = {ACS Applied Polymer Materials }, volume = {6}, year = {2024}, month = {MAY }, pages = {5754-5762}, type = {Article}, abstract = {

3D printing of poly(lactic acid) (PLA) blends has been attempted to resolve issues such as inherent brittleness and slow crystallization rate of PLA. However, a persistent challenge remains in the form of phase separation or gradual migration of the blended soft polymer or plasticizers. To simultaneously enhance the miscibility of the blends and toughness of 3D-printed parts, a triblock copolymer PLA-PEG-PLA was synthesized and blended with PLA in varying proportions (5, 10, 15, and 20 wt \%). Blending only 10-20 wt \% low molecular weight PLA-PEG-PLA into PLA yielded a miscible blend that showed a 45-fold increase in elongation at break and a 23-fold enhancement in toughness over neat PLA. Scanning electron microscopy (SEM) images of fractured cross sections revealed a brittle to ductile transition in 3D-printed PLA/PLA-PEG-PLA samples. Isothermal crystallization studies and data analysis using the Avrami equation showed an enhancement in the crystal growth rate and overall rate of crystallization. The blends achieved half of their crystallinity in approximately 3 min, a significant improvement over the 9 min required by PLA alone. This underscores the efficiency of our approach. This was also evident in the spherulite growth of 3D-printed PLA and mPLA blends when examined using polarized optical microscopy (POM). To the best of our knowledge, this is the first report exploring the use of blends that include PLA and low molecular weight PLA-PEG-PLA triblock copolymers for 3D printing applications.

}, keywords = {Crystallization, FFF 3D printing, PLA-PEG-PLA triblock copolymer, poly(lacticacid), toughness}, issn = {2637-6105}, doi = {10.1021/acsapm.4c00428}, author = {Kothavade, Premkumar and Yadav, Prashant and Gopal, Animesh and Pol, Harshawardhan and Kafi, Abdullah and Bateman, Stuart and Shanmuganathan, Kadhiravan} }