@article { ISI:000238928100018, title = {Preparation and characterization of novel hybrid of chitosan-g-lactic acid and montmorillonite}, journal = {Journal of Biomedical Materials Research Part A}, volume = {78A}, number = {2}, year = {2006}, month = {AUG}, pages = {372-382}, publisher = {WILEY-LISS}, type = {Article}, address = {DIV JOHN WILEY \& SONS INC, 111 RIVER ST, HOBOKEN, NJ 07030 USA}, abstract = {

The utilization of biopolymers and the development of organic-inorganic hybrids are ever increasing interest of material science researchers around the globe for various applications. The present attempt is intended to prepare nanocomposites of lactic acid grafted chitosan and layered silicates. Nanocomposites were prepared by dissolving chitosan and dispersing sodium montmorillonite in aqueous solution of L-lactic acid with subsequent heating and film casting. They were characterized by conventional techniques such as Fourier transform infrared spectroscopy, X-ray diffractometry, thermogravimetric analysis, energy dispersive X-ray spectroscopy, and elemental analysis. The results from polar optical and transmission electron microscopic measurements are also discussed. Sorption behavior of samples has been followed by measuring swelling degree and contact angle. The films have shown enhanced hydrophilicity when compared with polylactic acid (PLA). Issues on the interactions of polycationic chitosan with clay are also discussed. It is observed that nanocomposites are exhibiting better thermal and physical properties than neat chitosang-LA and PLA. (c) 2006 Wiley Periodicals, Inc.

}, keywords = {Chitosan, contact angle, graft copolymerization, Nanocomposites, polylactic acid, water absorption}, issn = {1549-3296}, doi = {10.1002/jbm.a.30738}, author = {Depan, Dilip and Kumar, Annamalai Pratheep and Singh, Raj Pal} } @article { ISI:000251014000004, title = {Photo-stabilization of EPDM-clay nanocomposites: effect of antioxidant on the preparation and durability}, journal = {Polymers for Advanced Technologies}, volume = {18}, number = {11}, year = {2007}, note = {International Conference on Frontier in Polymer Science and Technology, Calcutta, INDIA, FEB 10-12, 2006}, month = {NOV}, pages = {891-900}, publisher = {JOHN WILEY \& SONS LTD}, type = {Article}, address = {THE ATRIUM, SOUTHERN GATE, CHICHESTER PO19 8SQ, W SUSSEX, ENGLAND}, abstract = {

The present study is to examine the photo-stabilization effect of an antioxidant on the photo-oxidation of ethylene-propylene-diene monomer (EPDM)-clay nanocomposites. During the preparation of EPDM-clay nanocomposites via melt processing antioxidants are usually incorporated along with clay, which allows phenolic antioxidant molecules to get adsorbed onto acidic clay platelets and their interaction with metallic impurities reduces the stabilizing efficiency of the antioxidant. The nanocomposites were obtained by solution dispersion followed by melt compounding of EPDM and organophilic montmorillonite (OMMT). The samples were characterized by conventional tools such as X-ray diffraction (XRD), Fourier Transform Infra Red (FT-IR) spectroscopy, and thermo-gravimetric analysis (TGA). It was found, upon photo-irradiation (lambda \> 290 nm) studies by following the changes in functional groups and surface morphology, that photo-degradation was lowered by the antioxidant and the efficiency of the antioxidant could be improved by initial incorporation of antioxidant in the EPDM matrix. In EPDM-clay nanocomposites, a stabilizing activity of the antioxidant was observed above some threshold concentration of the antioxidant. The relationship between the nanoclay reinforcement and stabilizing efficiency in terms of photo-oxidation and surface morphology for their applicability are discussed. The methodology adopted for this study is also justified through our observation. Copyright (C) 2007 John Wiley \& Sons, Ltd.

}, keywords = {ethylene-propylene-diene monomer, nanocomposites photo-degradation antioxidant and stabilization}, issn = {1042-7147}, doi = {10.1002/pat.925}, author = {Lonkar, Sunil P. and Kumar, A. Pratheep and Singh, Raj Pal} } @article { ISI:000251802900022, title = {Preparation and characterization of novel hybrid of chitosan-g-PDMS and sodium montmorrilonite}, journal = {Journal of Biomedical Materials Research Part B-Applied Biomaterials}, volume = {84}, number = {1}, year = {2008}, month = {JAN}, pages = {184-190}, publisher = {WILEY-LISS}, address = {DIV JOHN WILEY \& SONS INC, 111 RIVER ST, HOBOKEN, NJ 07030 USA}, abstract = {

Preparation and properties of Chitosan (CS)-clay nanocomposites grafted with polydimethyl siloxane (PDMS) with different clay ratios are herein discussed. CS is intercalated into sodium montmorrilonite and PDMS is grafted onto CS under UV irradiation. Sample films of CS intercalated into clay and grafted with PDMS were prepared by solvent casting method with varying amount of nanoclay and PDMS. They were characterized by conventional techniques such as X-ray diffractometry, fourier transform infrared spectroscopy, C-13 NMR, thermo gravimetric analysis, and differential thermal analysis. Sorption behavior of samples has been followed by measuring swelling degree and issues on the interactions of biopolymers with clay are also discussed. The water absorption of composites films reduces with an increase in the amount of incorporated clay. This is due to the barrier formation in the form of cross-linking points, which prevents water permeation into CS. The amount of adsorbed water is more, when the amount of CS exceeds the amount of PDMS. This shows high water retention capacity of CS. (c) 2007 Wiley Periodicals, Inc.

}, keywords = {Chitosan, graft copolymerization, Nanocomposites, PDMS, water absorption}, issn = {1552-4973}, doi = {10.1002/jbm.b.30860}, author = {Depan, Dilip and Kumar, Bijandra and Singh, Raj Pal} } @article { ISI:000288092200005, title = {Preparation and characterization of bioceramic nanocomposites based on hydroxyapatite (HA) and carboxymethyl cellulose (CMC)}, journal = {Macromolecular Research}, volume = {18}, number = {12}, year = {2010}, month = {DEC}, pages = {1160-1167}, publisher = {SPRINGER}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

We report the synthesis of biomimetic nanocomposites based on carboxymethyl cellulose (CMC) and hydroxyapatite (HA) nanoparticles via a co-precipitation method. Physico-chemical characterization was performed before and after calcination by Fourier transform infrared (FTIR) spectroscopy, solid state (31)P nuclear magnetic resonance (NMR) spectroscopy, and thermogravimetric analysis (TGA). The formation of nanocomposites was observed by wide angle X-ray diffraction (WAXD), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), and transmission electron microscopy (TEM). The spectral and crystallographic data indicated the formation of hydroxyapatite in the presence of CMC. They were observed as aggregates of HA nanoparticles and CMC, whose sizes were approximately similar to 260 +/- 40 nm. The crystallite size of the hydroxyapatite particles decreased (with 2 wt\% 18 +/- 3 nm) with increasing CMC content. The morphological aspects of the calcined samples revealed the sintering ability of HA nanoparticles. Nanocomposites of hydroxyapatite nanoparticles that mimic the process of nucleation and growth in nature can be prepared using biomacromolecules such as CMC.

}, keywords = {biopolymer, cellulose, hydroxyapatite, Nanoparticles, Particle size, X-ray diffraction}, issn = {1598-5032}, doi = {10.1007/s13233-010-1208-3}, author = {Kumar, Annamalai Pratheep and Mohaideen, Kamal Khaja and Alariqi, Sameh A. S. and Singh, Raj Pal} } @article { ISI:000274069000060, title = {Preparation and characterization of novel hybrid of bio-assisted mineralized Zn-Al layered double hydroxides using chitosan as a template}, journal = {Journal of Applied Polymer Science}, volume = {115}, number = {6}, year = {2010}, month = {MAR}, pages = {3636-3644}, publisher = {JOHN WILEY \& SONS INC}, address = {111 RIVER ST, HOBOKEN, NJ 07030 USA}, abstract = {

The purpose of this study was to prepare and characterize a novel nanohybrid prepared from the template-assisted mineralization of Zn-Al Layered Double Hydroxide (LDH) onto the surface of Chitosan (CSI), with an emphasis on morphology, biocompatibitity, and its use as an efficient drug carrier agent. The as prepared LDH is highly crystalline, with platelet-like morphology and curved tactoids when nucleated onto the surface of CSI. Our results indicate that the -OH and -NH functional moieties on CSI can direct an ordered structure of LDH, due to the electrostatic interaction between biopolymer and inorganic lamellae. We have been successful to intercalate an anti-inflammatory drug, Sodium Ibuprofen (Ibu), into LDH, through conventional coprecipitation method. LDHs are endowed with great potential for delivery vector because their stacked layers lead to safe reservation of biofunctional molecules or genes, and their ion exchangeability and solubility in acidic media (pH \< 4) give rise to the controlled release of drug molecules. According to the cell-growth studies, LDHs are found as cell viable up to the concentration of 500 mu g/mL. This study reveals that LDH not only plays a role of a biocompatible-delivery matrix but also facilitates a significant increase in the delivery efficiency. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115:3636-3644,2010

}, keywords = {bio-assisted mineralization, cell-growth studies, Chitosan, drug delivery systems, layered double hydroxides}, issn = {0021-8995}, doi = {10.1002/app.31463}, author = {Depan, Dilip and Singh, Raj Pal} }