RESEARCH PAPER Effects of iron oxide nanoparticles on polyvinyl alcohol: interfacial layer and bulk nanocomposites thin film Zhanhu Guo • Di Zhang • Suying Wei • Zhe Wang • Amar B. Karki • Yuehao Li • Paul Bernazzani • David. P. Young • J. A. Gomes • David L. Cocke • Thomas C. Ho Received: 9 July 2009 / Accepted: 3 November 2009 / Published online: 19 November 2009 Ó Springer Science+Business Media B.V. 2009 Abstract Iron oxide (a-phase) nanoparticles with coercivity larger than 300 Oe have been fabricated at a mild temperature by an environmentally benign method. The economic sodium chloride has been found to effectively serve as a solid spacer to disperse the iron precursor and to prevent the nanoparticles from agglomeration. Higher ratios of sodium chloride to iron nitrate result in smaller nanoparticles (19 nm for 20:1 and 14 nm for 50:1). The presence of polyvinyl alcohol (PVA) limits the particle growth (15 nm for 20:1 and 13 nm for 50:1) and favors nanoparticle dispersion in polymer matrices. Obvious physicochemical property changes have been observed with PVA attached to the nanoparticle surface. With PVA attached to the nanoparticle surface, the nanoparticles are found not only to increase the PVA cross-linking with an increase in melting temperature but also to enhance the thermal stability of the PVA. The nanoparticles are observed to be uniformly dispersed in the polymer matrix. Scanning electron microscopy (SEM) microstructure also shows an intermediate phase with a strong interaction between the nanoparticles and the poly- mer matrices, arising from the hydrogen bonding between the PVA and hydroxyl groups on the nanoparticle surface. The addition of nanoparticles favors the cross-linkage of the bulk PVA matrices, resulting in a higher melting temperature, and an enhanced thermal stability of the polymer matrix. Keywords Nanoparticles  Polymer nanocomposites  Thermal properties Introduction Antiferromagnetic a-Fe 2 O 3 (hematite) nanoparticles (NPs) have attracted much interest due to their wide potential applications in many areas, such as pigments (Feldmann 2001), catalysts (Glisenti 1998; Ren et al. 2009; Rofer-Depoorter 1981; Xie et al. 2009; Zhang et al. 2009; Zheng et al. 2007), photocatalysts (Kay et al. 2006), gas sensors (Fukazawa et al. 1993; Huo et al. 2005; Neri et al. 2002; Wang et al. Z. Guo (&)  D. Zhang  Y. Li  J. A. Gomes  D. L. Cocke  T. C. Ho Integrated Composites Laboratory (ICL), Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, TX 77710, USA e-mail: zhanhu.guo@lamar.edu S. Wei  P. Bernazzani Department of Chemistry and Physics, Lamar University, Beaumont, TX 77710, USA Z. Wang Mechanical and Aerospace Engineering Department, University of California Los Angeles, Los Angeles, CA 90095, USA A. B. Karki  David. P. Young Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA 123 J Nanopart Res (2010) 12:2415–2426 DOI 10.1007/s11051-009-9802-z