@article { ISI:000343613000075,
	title = {Supramolecular transitions in native cellulose-I during progressive oxidation reaction leading to quasi-spherical nanoparticles of 6-carboxycellulose},
	journal = {Carbohydrate Polymers},
	volume = {113},
	year = {2014},
	month = {NOV},
	pages = {615-623},
	publisher = {ELSEVIER SCI LTD},
	address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND},
	abstract = {<p>Cellulose-I swells considerably in phosphoric acid, and converts to amorphous cellulose via a cellulose-II transition state. Controlled oxidation of cellulose-I to 6-carboxycellulose (6CC) using HNO3-H3PO4-NaNO2 oxidation system led to the selective production of 6CC{\textquoteright}s of varying carboxyl contents (1.7-22\%) as well as various shapes and sizes (macro-sized fibrils of several micron length and/or spherical nanoparticles of 25-35 nm), depending on the reaction conditions. 6CC{\textquoteright}s having less than 14\% carboxyl content were largely in cellulose-II form (WAXRD values in-between cellulose I and cellulose II), whereas at 14-22\% the 6CC{\textquoteright}s were largely amorphous; only trace crystallinity was observed at 19\% and 22\% carboxyl 6CC. Spherical nanoparticles retained a high degree of crystallinity having cellulose-I structure, whereas the macro-sized fibrils were largely converted to cellulose-II structure. Analysis by WAXRD as well as by CP-MAS C-13 NMR studies gave similar conclusions. Reduced molecular weight with progressive oxidation, including presence of oligomers, was also evident from an increase in the reducing-end carbon peak at similar to 92 ppm. For high oxidation levels (\&gt;14\%) the NMR 92-96 ppm peaks disappeared on extracting with dilute alkali, due to soluble oligomers being removed. (C) 2014 Elsevier Ltd. All rights reserved.</p>},
	keywords = {Carboxycellulose, cellulose, Nanoparticles, NMR, WAXRD},
	issn = {0144-8617},
	doi = {10.1016/j.carbpol.2014.07.056},
	author = {Sharma, Priyanka R. and Rajamohanan, Pattuparambil R. and Varma, Anjanikumar}
}
