Paper surfaces functionalized by nanoparticles
Graphical Abstract
Research Highlights
► Photocatalytic, SPR, SERS, antimicrobial properties of nanoparticles are reviewed. ► Control of morphology and structure of paper enhances nanoparticles’ performance. ► Spatial location and adsorption of nanoparticles on paper need to be optimized. ► Main applications of the nanoparticles-functionalized papers are highlighted. ► Heterogeneity and light interaction between nanoparticles and paper are critical.
Introduction
The area of nanotechnology reviewed in this article involves controlled deposition of individual nanoparticles or their aggregates into desired configurations on paper, to produce materials with unique properties and functions [1]. Nanoparticles with distinctive electronic, optical and catalytic properties have been at the forefront of research due to their tremendous applications. A wide range of techniques have been used to synthesize nanoparticles in different solid mediums, such as glass [2], metallic [3] and polymeric films [4] to realize new applications. However, development of simpler and more direct methods is still needed to readily generate the desired size, shape, and adsorption of nanoparticles on appropriate and strategic substrates. Taking gold (AuNPs), silver (AgNPs) and titania nanoparticles (TiO2) (Table 1) as examples, the state of paper functionalized by these nanoparticles is analyzed in this review.
The porous structure and hydrophilic fiber surface allow paper to absorb suspensions of nanoparticles by capillary forces, yielding a high loading of nanoparticles upon drying. Furthermore, paper is a low cost substrate and only a very small volume of TiO2, AuNPs and AgNPs deposited on paper can produce devices which show excellent optical [5], antibacterial [6], [7], anti-counterfeiting [8], Surface Enhanced Raman Scattering (SERS) [9] and Surface Plasmon Resonance (SPR) [10] performances. In addition, paper has the advantage of being biodegradable, biocompatible and renewable whilst its structural morphology as well as surface chemistry can be readily engineered.
The objectives of this article are to critically review the development of nanoparticles-functionalized paper and assess missing knowledge and opportunities. A brief overview of the properties of TiO2, AuNPs and AgNPs is presented first, to provide a background for further discussion of the nanoparticles-functionalized paper. These nanoparticles have been selected due to their wide usage and unique applications. This review then focuses on the deposition/assembly and applications of the nanoparticles-functionalized paper. Finally, the future challenges and opportunities of this field are presented.
Section snippets
Properties of nanoparticles
Before analyzing the preparation methods and applications of nanoparticles-functionalized paper, the properties of TiO2, AuNPs and AgNPs (Table 1) are presented in this section. Due to extensive range of properties displayed by these three nanoparticles, we only intend to provide a brief overview of their photocatalytic, Surface Plasmon Resonance (SPR), Surface Enhanced Raman Scattering (SERS) and antibacterial properties which are related to the end-use of the respective
Attachment methods of nanoparticles to paper
There are many publications and patents describing methods of attachment/binding of nanoparticles onto paper, particularly for TiO2-functionalized paper. A brief review of the major strategies is presented in this section. Basically, there are two approaches for attaching nanoparticles onto paper, “wet-end addition”, where nanoparticles are adhered onto individual fibers before paper sheet formation, and “surface treatment”, where dry paper sheet is impregnated with nanoparticles by passing
Self-cleaning
The unique combination of photocatalytic and hydrophilic properties of TiO2 has markedly increased their application range, especially as a coating on cellulosic materials such as paper [45]. The ability of water to soak between stain and highly hydrophilic TiO2 surface results in easy and efficient stain removal. Hence, TiO2-coated surfaces have been widely used in outdoors. An example is a Japanese paper window blind with excellent self-cleaning properties, wherein stain is decomposed by
Challenges and opportunities
Most studies have relied on paper as an inert support for nanoparticles and very few, if any, have considered the distribution of nanoparticles in the three dimensions (3D) of paper, or the concept of heterogeneity and the effect of manipulating different length scales possible. Furthermore, little attention has been devoted to engineer the properties of nanoparticles-paper composite. In some instances of photocatalysis, SPR and SERS, nanoparticles on paper have provided better properties than
Conclusion
A critical review of the properties, attachment methods and applications of nanoparticles-functionalized paper has been presented. Three types of nanoparticles were reviewed: titania, AuNPs and AgNPs. Paper is a low cost, cellulosic non-woven and only a very small volume fraction of these nanoparticles is needed to significantly alter its properties, especially the photocatalytic and optical properties. The emerging applications of nanoparticles-functionalized paper mostly involve interaction
Acknowledgements
Many thanks to Dr. Peter Miller and Dr. Tim Williams from the Monash Centre for Electron Microscopy (MCEM) for discussions and SEM technical suggestions. The financial supports of the ARC Linkage – Project grant (LP0989823), the Australian Pulp and Paper Institute and Monash University are acknowledged.
References (74)
- et al.
Preparation of silver nanoparticles dispersed in polyacrylonitrile nanofiber film spun by electrospinning
Mater Lett
(2005) - et al.
Graft copolymerization onto cellulose-based filter paper and its further development as silver nanoparticles loaded antibacterial food-packaging material
Colloids Surf, B
(2009) - et al.
Metal-enhanced fluorescence from paper substrates: modified spectral properties of dyes for potential high-throughput surface analysis and assays and as an anti-counterfeiting technology
Dyes Pigm
(2008) - et al.
The adsorption behavior of p-hydroxybenzoic acid on a silver-coated filter paper by surface enhanced Raman scattering
J Colloid Interface Sci
(2003) - et al.
Photoinduced reactivity of titanium dioxide
Prog Solid State Chem
(2004) - et al.
Photocatalytic oxidation of nitrogen oxide over titania-zeolite composite catalyst to remove nitrogen oxides in the atmosphere
Appl Catal, B
(2001) - et al.
Titanium dioxide photocatalysis
J Photochem Photobiol, C
(2000) - et al.
Raman spectra of pyridine adsorbed at a silver electrode
Chem Phys Lett
(1974) - et al.
Silver nanoparticles: green synthesis and their antimicrobial activities
Adv Colloid Interface Sci
(2009) - et al.
Photocatalytic paper from colloidal TiO2–fact or fantasy
Adv Colloid Interface Sci
(2006)