Role of particle size in individual and competitive diffusion of carboxylic acid derivatized colloidal gold particles in thermally evaporated fatty amine films
V. Patil et al., Role of particle size in individual and competitive diffusion of carboxylic acid derivatized colloidal gold particles in thermally evaporated fatty amine films, LANGMUIR, 15(23), 1999, pp. 8197-8206
We have recently shown that nanocomposites of colloidal particles in a fatt
y lipid matrix can be grown via a diffusion process controlled by selective
electrostatic interactions. In this paper, a detailed investigation of the
diffusion of carboxylic acid derivatized gold colloidal particles of diffe
rent sizes into thermally evaporated octadecylamine films using quartz crys
tal microgravimetry (QCM), transmission electron microscopy, and W-vis abso
rption and Fourier transform infrared (FTIR) spectroscopies is described. T
he QCM kinetics of gold cluster incorporation has been analyzed in terms of
a one-dimensional Fickian-type diffusion model, and it is found that the c
luster diffusivity increases with decreasing cluster size. The pH at which
maximum cluster incorporation in the amine occurs was found to be dependent
on the cluster size as well. FTIR spectroscopy of the fatty amine-gold par
ticle composites indicated weak coupling of the clusters to the protonated
amine groups as well as interesting cluster size dependent changes in the a
mine and methylene antisymmetric deformations as well as the methylene scis
soring bands. In a competitive diffusion process of large and small gold pa
rticles, it was observed that bigger gold particles were preferentially inc
orporated into the amine matrix even though the cluster diffusivity is high
er for the smaller gold particles.