Dynamic scaling and kinetic roughening of poly(ethylene) islands grown by vapor phase deposition

• PVD growth of PE islands proceeds in the 2D regime until strong coalescence occurs.
• Quasi-dynamic scaling is observed in the range of coverage 0.1 < θ < 0.3.
• Scaling exponents are αloc = 0.67, αs = 0.85, β = 0.33 (0.2 for the late growth) and z = 2.2.
• The scaling exponents do not match any known universality classes.
• Macromolecular relaxation at island edges is responsible for the inconsistence.

Vapor phase deposition of poly(ethylene) is shown to produce uncross-linked thin films consisting of linear (CH2)100 oligomers with narrow molar mass distribution of dispersity DM = 1.10. Early stages of the film formation are characterized by the growth of two-dimensional compact islands of constant 7–8 nm thickness. The transversal evolution of islands is studied in the context of the Dynamic Scaling Theory. The aggregation regime is found to be valid in a narrow range of coverage 0.1 < θ < 0.3. The critical island size is estimated to be i = 1. Kinetic roughening of the growing front gives a set of the scaling exponents αloc = 0.67, αs = 0.85, β = 0.33 (β = 0.2 for the late stages of growth) and z = 2.2 that does not fit into any of the known universality classes. Macromolecular relaxation at the island edges is suggested to explain the observed inconsistence.