The surface morphologies of poly(chloro-p-xylylene) films were measured using atomic force microscopy and analyzed within the frame work of the dynamic scaling theory. The evolution of polymer films grown with fixed experimental parameters showed drastic changes of dynamic roughening behavior, which involve unusually high growth exponent (beta = 0.65+-0.03) in the initial growth regime, followed by a regime characterized by beta~0, and finally a crossover to beta = 0.18+-0.02 in a steady growth regime. Detailed scaling analysis of the surface fluctuation in Fourier space in terms of power spectral density revealed a gradual crossover in the global roughness exponent, analogous to a phase transition between two equilibrium states, from a morphology defined by alpha=1.36+-0.13 to the other morphology characterized by alpha=0.93+-0.04 as the film thickness increases. Our experimental results which significant deviate from the well established descriptions of film growth clearly exhibit that the dynamic roughening of polymer film is deeply affected by strong molecular interactions and relaxations of polymer chains.Comment: Accepted for publication in Physical Reveiw

The evolution of island formation during submonolayer growth of poly(chloro-p-xylylene) films on naturally grown silicon oxide substrates is investigated using atomic force microscopy (AFM), and analyzed within the framework of dynamic scaling theory. A transition of film growth mechanism from diffusion-limited aggregation to reaction-limited aggregation is dramatically displayed in an unprecedented progression of the island density distribution functions. As surface coverage increases, a conventional bell-shaped monomodal distribution in early growth regime (θ = 0.07) gradually changes to a monotonically decreasing function, approximately following a power-law. The marginal power-law scaling behavior of the island distribution functions, reminiscent of the behavior of colloid aggregation, strongly suggests that film growth by vapor deposition polymerization is a new type of surface growth governed by reaction-limited aggregation process in which the competition between diffusion and deposition does not define the typical time scale of film growth.