Chitosan nanofibrous materials for chemical and biological protection

Abstract

Chitosan derivatives are difficult to electrospun because they have poor flexibility of their polyelectrolyte chains. Based on extensive trails, we have successfully electrospun chitosan polymer and, subsequently, coated on non-woven polypropylene utilizing Nanospider technology. This experimentally developed nanofibrous webs of various densities were coated on non-woven fabric and, subsequently, stitched with activated carbon sphere (ACS) adhered composite fabric. Biological filtration and chemical protection were evaluated and the optimized density offering the highest value with meeting specified comfort was assessed. Results showed that optimized web morphology of 0.43 g m−2 is the best for integration with nuclear, biological and chemical absorbent layer of low ACS add-on in all aspects of comfort and protective behaviours. This will be meeting stringent defence protective requirements and lowering down the weight of suit by approximately 25%. An attempt has also been made in this research to protect from sulphur mustard chemical warfare agent by using both theories: (a) barrier techniques and (b) disintegrating the trapped molecules via functionalization of the web. Result shows that first molecules get trapped by in web layer (barrier effect) and subsequently destroyed by hydrolysis mechanism. Scanning microscopic image shows web is acting as barrier layer by trapping sulphur mustard particles. Optimized web of 0.43 g m−2 was functionalized with zinc (Zn) oxide and the presence of Zn particles was confirmed by imaging techniques. Crystalline and thermal analysis depicts that structural changes were found in sulphur mustard spotted functionalized web. Raman spectra show chemically disintegrated hydrolysed products of sulphur mustard. Bacterial filtration efficiency, antimicrobial and comfort properties were measured for assessing the introduction of nanowebs for biological protection and chemical protection in newly created multilayered fabric structure with low ACS add-on (180 g m−2). The initial encouraging outcome of this research expects whether the multilayered fabric could be introduced in the suit.