Langmuir, Vol.21, No.7, 2981-2987, 2005
Poly(ethylene glycol) self-assembled monolayer island growth
Here, we report a study of the morphology and growth dynamics of a self-assembled monolayer (SAM) of the amide containing poly(ethylene glycol) (PEG) thiol (CH3O(CH2CH2O)(17)NHCO(CH2)(2)SH) on atomically flat Au(111) surfaces. SAM growth from a 20 mu M ethanolic solution reveals island growth through three distinct steps: island nucleation, island growth, and coalescence. The coalescence-step, filling voids in the SAM, is by far slowest. The fine structure study reveals dendritic island formation, an observation which can be explained by attractive intermolecular interactions and surface diffusion-limited aggregation. We have also observed a change in the island height, which peaks during the island growth phase. This height change can be associated with a molecular conformational transition.