Functionalised nanostructured polyaniline? A new substrate for building adaptive sensing surfaces

A new method for covalently binding side-chains to the surface of solution based conducting polymer nanostructures is introduced in this paper. Modification of the structures is achieved by convenient reflux in the presence of a nucleophile, and post-functionalization purification is subsequently carried out by centrifugation. The entire process is easily scalable and hence suitable for bulk production of functionalized nanomaterials. In particular we focus on the modification of polyaniline nanofibres which can be synthesized by interfacial polymerization. Mercaptoundecanoic acid side-chains are attached to the polymer nanostructures, with the intrinsic nano-morphology of the material being maintained during the process. The modified PAni nanofibres provide a template for the attachment of other specific functional groups which could be used to target a particular species

Towards the development of adaptive nanostructured platforms

Since their discovery in 1977, intrinsically conducting polymers have been studies for applications such as electronic devices, sensors and actuators[1-3]. Polyaniline (PAni) is an example of a stable conducting polymer and can be classified as an ‘adaptive material’ in that it can be switched between two or more forms (each with their own distinct characteristics) using an external stimulus. In contrast to a classical metallic conductor or a polymeric insulator, PAni can be switched reversibly between an insulating emeraldine base form and a conducting emeraldine salt. More recently, interest has developed in the area of nanostructured polyaniline[4-6]. These one-dimensional objects combine the advantages of an organic conductor and a high surface area material, thus making them suitable for a diverse range of applications such as chemical sensors, flash memory and electro-optic devices[7-9]. Here we present how polyaniline nanofibres can be successfully functionalised with both amine and carboxylate groups. The modified nanofibres maintain their ability to switch between diffferent forms displaying distinctly different optical properties (as shown by Raman and UV-vis spectroscopy), thus making them suitable for adaptive sensing applications. The attachment of functional groups to polyaniline nanofibres provides a route for manipulating the surface chemistry of nanofibres. While interesting materials in themselves, these functionalised nanofibres are also attractive as molecular scaffolds for building yet more innovative derivatives that nonetheless retain the basic underlying nanostructure and intrinsic characteristics of PAni. That we have demonstrated the ability to regulate the extent of side-chain attachment to one-dimensional objects, in a safe and simple manner, represents a step forward in the area of adaptive nano-structured materials. Functionalisation can be controlled using a simple, scalable and inexpensive technique[10-11]. [1] C. O. Baker, B. Shedd, P. C. Innis, P. G. Whitten, G. M. Spinks, G. G. Wallace, R. B. Kaner, Adv Mater 20 (2008) 155-+. [2] W. R. Small, F. Masdarolomoor, G. G. Wallace, M. Panhuis, J Mater Chem 17 (2007) 4359-4361. [3] J. G. Roh, H. R. Hwang, J. B. Yu, J. O. Lim, J. S. Huh, Journal of Macromolecular Science-Pure and Applied Chemistry A39 (2002) 1095-1105. [4] J. X. Huang, R. B. Kaner, Chemical Communications (2006) 367-376. [5] N. R. Chiou, C. M. Lui, J. J. Guan, L. J. Lee, A. J. Epstein, Nat. Nanotechnol. 2 (2007) 354-357. [6] F. Masdarolomoor, P. C. Innis, S. Ashraf, R. B. Kaner, G. G. Wallace, Macromol. Rapid Commun. 27 (2006) 1995-2000. [7] S. Virji, J. X. Huang, R. B. Kaner, B. H. Weiller, Nano Lett. 4 (2004) 491-496. [8] S. Virji, R. B. Kaner, B. H. Weiller, J. Phys. Chem. B 110 (2006) 22266-22270. [9] S. Virji, R. B. Kaner, B. H. Weiller, Chemistry of Materials 17 (2005) 1256-1260. [10] E. Lahiff, T. Woods, W. Blau, G.G. Wallace, D. Diamond, Synth. Metals, accepted. [11] E. Lahiff, S. Bell, D. Diamond, Mat. Res. Soc. Symp. Proc., Vol. 1054, FF-05-05, 200

Business models in land reform

This paper reviews the types of business models, or landuse models, being implemented in land reform projects involving the transfer of rural land to communities and other groups in South Africa, under both the restitution and redistribution programmes. It draws heavily on the series of Diagnostic Studies prepared as part of the Sustainable Development Consortium’s (SDC) work on post-settlement support, but also draws from other studies on restitution, notably that conducted by the Community Agency for Social Enquiry (CASE) in 2005, and the wider literature on redistributive land reform in South Africa.Belgian Technical Cooperation (BTC

Functionalised polyanaline nanofibers

Polyaniline (PAni) is a conducting polymer which switches between distinct states exhibiting dramatically different properties. The colour, conductivity and redox state of PAni all depend on the local chemical environment of the material. Consequently PAni has great potential for sensing applications. The nanostructured form of PAni is particularly interesting as it provides a very large surface-to-volume ratio that can lead to dramatic enhancement of sensor sensitivity and response time. In this work, we focus on derivatising polyaniline nanofibres. Using the technique described, carboxylate terminated side-chains can be covalently bound to solution based fibres

Student learning and engagement in Project-based learning (PjBL) activities

In response to evolving work practices in engineering, renewed attention has turned to the development of innovative pedagogies to facilitate the entry of graduates into the employment market. Project-based Learning (PjBL) in interdisciplinary groups has been developed in HE contexts to provide students with authentic learning experiences to facilitate the transition to 21st century workplaces. Yet despite the introduction of innovative PjBL and broader inquiry-based curricula, comprehensive understanding of the pedagogical practices has not yet emerged. This presentation session will identify and discuss student learning and engagement in Project-based Learning activities