Submitted to: Cellulose
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/18/2014
Publication Date: 5/3/2014
Citation: Nam, S., Condon, B.D. 2014. Internally dispersed synthesis of uniform silver nanoparticles via in situ reduction of [Ag(NH3)2]+ along natural microfibrillar substructures of cotton fiber. Cellulose. 21:2963-2972.
Interpretive Summary: Silver nanoparticles (Ag NPs) are effective antimicrobial agents, but their application on the surface of a fiber renders them ineffective because Ag NPs are washable. We report a method of making Ag NPs durable by the in-situ formation of Ag NPs inside the cotton fiber during mercerization. Ag complex ions were diffused into the alkali-swollen cotton and assembled on the cellulose surface by the electrostatic interaction. Reduction reaction and particle growth were controlled by the microfibrillar channel flow, producing monodispersed Ag NPs (21'4 nm) in the entire of cross-section of the fiber at room temperature within several minutes. This stable, non-leaching Ag-cotton nanocomposite will find many uses in technical applications that require continuous, long-lasting antimicrobial activity.
Technical Abstract: Silver nanoparticles (Ag NPs) are known to have efficient antimicrobial properties, but the direct application of Ag NPs onto the surface of textiles has shown to be ineffective and raise environmental concerns because Ag NPs leach out during washing. In this study, non-leaching and stable Agcotton nanocomposite fiber was produced by the in situ formation of Ag NPs inside the cotton fiber. The reported method is to introduce a nanofluidic system in alkali-swollen cotton fiber. Sequential flows of [Ag(NH3)2]? and reductant aqueous fluids into the opened microfibrillar channels yielded a self-assembly of Ag ions on the deprotonated cellulose and subsequent nucleation and particle growth on the microfibrils. Transmission electron and field emission scanning electron microscopy images showed Ag NPs evenly dispersed throughout the entire cross-section of the fiber and their fixation onto the isolated secondary cell wall, respectively. Despite the rapid reduction reaction and the absence of a stabilizing agent, the successful formation of monodispersed Ag NPs (12 ± 3 nm) was attributed to the self-controlled function of the highly organized microfibrillar substructures, which regulated the transport and mixing of reactants. Incorporation of Ag NPs into the internal structure of the cotton fiber did not significantly influence the cotton crystalline structure.