@article { ISI:000312472000040, title = {Gold nanoparticle embedded hydrogel matrices as catalysts: better dispersibility of nanoparticles in the gel matrix upon addition of N-bromosuccinimide leading to increased catalytic efficiency}, journal = {Colloids and Surfaces A-Physicochemical and Engineering Aspects}, volume = {414}, year = {2012}, month = {NOV}, pages = {296-301}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A simple and convenient method for generating and immobilizing gold NPs into polyethylene glycol-polyurethane (PEGPU) matrices is presented. The gold NP immobilized PEGPU (Au NP-PEGPU) hydrogel matrices are easy to handle and can be used as catalysts. The efficiency, reusability and durability of the Au NP-PEGPU catalyst matrices were investigated using the reduction of 4-nitroaniline (4NA) to p-phenylenediamine (p-PDA) by sodium borohydride in the presence of the catalyst as a test reaction. The Au NPs in the PEGPU matrix got aggregated after 3 cycles of catalysis but dispersion could be regenerated by the addition of N-bromosuccinimide (NBS). After this regeneration process the Au NPs-PEGPU matrix showed excellent efficiency without any aggregation, leaching or degradation. The reusability of the catalyst for 28 cycles yielding a total turnover number of 3220 and turn over frequency of 0.152 s(-1) is demonstrated. (C) 2012 Elsevier B.V. All rights reserved.

}, keywords = {catalysis, hydrogels, Immobilization, Nanoparticles, Turn over numbers}, issn = {0927-7757}, doi = {10.1016/j.colsurfa.2012.08.026}, author = {Ramtenki, Vilas and Anumon, V. D. and Badiger, Manohar V. and Bhagavatula L. V. Prasad} } @article { ISI:000349401200010, title = {Porous poly(ethylene glycol)-polyurethane hydrogels as potential biomaterials}, journal = {Polymer International}, volume = {64}, number = {3}, year = {2015}, month = {MAR}, pages = {397-404}, publisher = {WILEY-BLACKWELL}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {

We report the synthesis of porous poly(ethylene glycol)-polyurethane (PEG-PU) hydrogels using PEG-4000 as a soft segment and 4,4-methylenebis(cyclohexylisocyanate) as a hard segment. The degree of swelling in the hydrogels could be controlled by varying the amount of crosslinking agent, namely 1,2,6-hexanetriol. Structural characterization of the hydrogels was performed using solid-state C-13 NMR and Fourier transform infrared spectroscopy. Wide-angle X-ray diffraction studies revealed the existence of crystalline domains of PEG and small-angle X-ray scattering studies showed the presence of lamellar microstructures. For generating a porous structure in the hydrogels, cryogenic treatment with lyophilization was used. Scanning electron microscopy and three-dimensional micro-computed tomography imaging of the hydrogels indicated the presence of interconnected pores. The mechanical strength of the hydrogels and xerogels was measured using dynamic mechanical analysis. The observed dynamic storage moduli (E) for the equilibrium swollen and dry gels were found to be 0.15 and 4.2 MPa, respectively. Interestingly, the porous PEG-PU xerogel also showed E of 5.6 MPa indicating a similar mechanical strength upon incorporating porosity into the gel matrix. Finally, preliminary cytocompatibility studies showed the ability of cells to proliferate in the hydrogels. These gels show promise for applications as scaffolds and implants in tissue engineering. (c) 2014 Society of Chemical Industry

}, keywords = {hydrogels, permeability, poly(ethylene glycol), polyurethane, porosity}, issn = {0959-8103}, doi = {10.1002/pi.4802}, author = {Divakaran, Anumon V. and Torris, Arun A. T. and Lele, Ashish K. and Badiger, Manohar V.} } @article {43806, title = { Design and development of trivalent aluminum ions induced self healing polyacrylic acid novel hydrogels}, journal = {POLYMER}, volume = {126}, year = {2017}, month = {SEP}, pages = { 196-205}, type = {Journal Article}, chapter = {196-205}, abstract = {

Development of ionically crosslinked superabsorbent polyacrylic acid (PAA) self-healing hydrogels using trivalent aluminum ions was investigated. The PAA hydrogels exhibited excellent self-healing behavior depending on the amount of the aluminum within the matrix. The migration of these ions within the polymer matrix was responsible for the physical crosslinking of the hydrogel and the origin of self healing ability. The PAA-Al hydrogels were insoluble in water and exhibited significantly high degree of swelling (similar to 4000\%). Hydrogel also exhibited good mechanical properties with high level of elongation. Excellent self-healing efficiency was observed under dynamic as well as oscillatory Theological measurements. The presence of Al ions within PAA hydrogel facilitated the self-healing ability because of the ionic interaction in these gels which plays the key role of dynamic reversible sacrificial bonds which reforms upon reversal of the deformative force. (C) 2017 Elsevier Ltd. All rights reserved.

}, keywords = {Aluminum chloride, Behavior, Complex, Composite, crosslinking, Delivery, High-Mechanical Strength, hydrogels, Network, Polyacrylic acid, Polymeric Materials, Self-healing, swelling, Tough; pH}, issn = {0032-3861}, doi = {10.1016/j.polymer.2017.08.045}, author = {Anjum, Sadiya and Gurave, Pramod and Badiger, Manohar V. and Tiwari, Neha and Gupta, Bhuvanesh} }