PREPARATION OF CHITIN NANOFIBERS-GOLD METALLIC NANOCOMPOSITE BY PHASE TRANSFER METHOD

Abstract

Chitin nanofibers (CNFs)- Au(0) nanoparticles ( Au NPs) blends in dispersion, flakes and thin film or sheet forms were first prepared by mixing pre-organized Au NPs prepared in triblock copolymer with diluted CNFs suspension. Water soluble polymer triblock copolymer poly (methyl vinyl ether, PMVE) in the amount 0.6 wt.% was used to prepare NPs and 0.12 wt.% net chitin content was used as CNFs suspension to prepare the blended composite. Au NPs of size 4.4 nm (σ = 1.2) were obtained when Au salt ( HAuCl4⋅3H2O (hydrogen tetrachloroaurate (III) trihydrate) was reduced by 5 equivalents of NaBH4 . PMVE polymer acted as a stabilizing or capping agent for pre-organized NPs. Completion of reaction was fast, all salt reduced to metallic form in just 15 min after the addition of NaBH4 . CNFs (1 wt.% chitin) which was used to prepare CNFs- Au NPs blend composite were prepared from crab shell in never dried acidic condition by established combination of chemical and mechanical processes that gave 25–40 nm width and high aspect ratio CNFs. When polymer capped Au NPs mixed with CNF suspension, all Au NPs and 56% polymer were mass transferred from water phase to entangle with more polar moieties of CNFs-water suspension as no trace of Au NPs were noticed in water–polymer mother liquor after blending with CNFs suspension. Particles size of CNFs- Au NPs composite was measured by employing TEM, SAXS and SEM techniques. CNFs- Au NPs composite were characterized in solution and compressed dried sheet form by recording digital images, UV-vis and XRD spectroscopies. CNFs- Au NPs suspension had antibacterial activity against gram positive bacteria S. aureus.