SURFACE DERIVATIZATION OF COLLOIDAL SILVER PARTICLES USING INTERDIGITATED BILAYERS - A NOVEL STRATEGY FOR ELECTROSTATIC IMMOBILIZATION OF COLLOIDAL PARTICLES IN THERMALLY EVAPORATED FATTY-ACID FATTY AMINE FILMS

We have recently demonstrated that interdigitated bilayers of fatty ac id molecules self-assemble on nanoscale curved surfaces, thereby highl ighting an important difference between self-assembly on planar surfac es where such structures have not been reported to form. On a more pra ctical level, this approach leads to a new strategy for derivatization of colloidal particle surfaces without the use of terminally function alized molecules. In this paper, we use this new strategy to derivatiz e colloidal silver particle surfaces with carboxylic acid and amine fu nctional groups and, thereafter, to incorporate the colloidal particle s in thermally evaporated conjugate fatty lipid films via electrostati cally controlled diffusion from the sol. The diffusion of the colloida l particles in the thermally evaporated organic films has been followe d using quartz crystal microgravimetry and modeled on the basis of a 1 -D diffusion process and the cluster diffusivities determined. It is o bserved that both the charge on the clusters and the length of the alk yl tail of the molecules in the secondary monolayer (via a hydrophobic interaction contribution) influence the cluster diffusivity in the th ermally evaporated films. The cluster-incorporated films have been fur ther characterized using optical absorption spectroscopy and X-ray pho toemission spectroscopy.