Journal of Colloid and Interface Science 292 (2005) 71–78 www.elsevier.com/locate/jcis Self-assembly of 1,4-phenylene diisocyanide and terephthalic acid on Ni, Cu and Pt Lawrence Pranger ∗ , Rina Tannenbaum School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA Received 6 April 2005; accepted 18 May 2005 Available online 22 June 2005 Abstract This paper compares the adsorption behavior of 1,4-phenylene diisocyanide (PDI) and terephthalic acid (TA) on Ni, Cu and Pt surfaces. Following competitive adsorption from two-component equimolar solutions of PDI and TA, chemical analysis by XPS confirmed the prefer- ential adsorption of PDI over TA on Ni and Cu. The ability to form “chemically sticky” surfaces on Ni, Cu and Pt surfaces by self-assembly into organized organic thin films (OOTFs) was also investigated. PM-IRRAS analysis revealed a tendency for PDI to bond in a terminal fashion through one isocyanide group, on both Ni and Cu. In contrast, PDI adsorbed in a flat configuration on Pt. Chemically sticky OOTFs have potential for utilization as coupling agents to achieve a high cross-link density and enhance stress transfer between the nanoclusters and the organic matrix molecules in metal-nanocluster-filled polymer matrix nanocomposites. The results of this work indicate that 1,4-phenylene diisocyanide is a suitable choice as a coupling agent for metal nanoclusters of Ni and Cu.  2005 Elsevier Inc. All rights reserved. Keywords: Self-assembly; XPS; PM-IRRAS; Terephthalic acid; Phenylene diisocyanide 1. Introduction Organized organic thin films (OOTFs) have been suc- cessfully prepared on a variety of substrates to study and to optimize surface properties such as wetting, chemical resistance, and biocompatibility [1]. Such films are spon- taneously formed when amphiphilic surfactant molecules, e.g., short-chain alkane thiols or fatty acids, are allowed to self-assemble into a monolayer or multilayer structure on a specific substrate [2,3]. When difunctional molecules bear- ing reactive functional groups at each end are selected in lieu of amphiphiles, “chemically sticky” OOTFs can be pre- pared [4]. Such films increase the range of possibilities for tailoring a surface, by providing a means of bonding adlayers to the target substrate. For example, metal nanoclusters and polymer layers have been anchored to metal or semiconduc- tor surfaces [5–7]. Chemically sticky surfaces have impor- * Corresponding author. Fax: +1 404 894 9140. E-mail address: gtg008m@mail.gatech.edu (L. Pranger). tant applications in nanocomposites, where the interphase between the matrix and the filler must be controlled at the nanometer scale. For example, when applied to the surface of metal nanoparticles, OOTFs play a critical role as a protec- tive molecular coating, stabilizing the nanoparticles [8–10]. Stabilizing nanoparticles against further growth is critical for retaining their size-dependent properties in nanostructured materials [11]. In polymer matrix nanocomposites, “chem- ically sticky” OOTFs can be utilized as coupling agents to enhance bonding between nanoparticles and a polymer ma- trix, in addition to their role of stabilizing the nanoparticles, as illustrated in Fig. 1. The self-assembly of difunctional molecules is compli- cated compared to the case of simpler surfactants, by the fact that both terminal functional groups are reactive and may have comparable affinity for the target substrate. To pro- duce a chemically sticky OOTF, the constituent difunctional molecules must bond to the substrate through only one ter- minal, and collectively form a chemically reactive surface with the terminal group disposed away from the substrate 0021-9797/$ – see front matter  2005 Elsevier Inc. All rights reserved. doi:10.1016/j.jcis.2005.05.044