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Structural evolution of polytetrafluoroethylene latex polymer films has been studied by Brillouin light scattering and atomic force microscopy (AFM). Using a tunable sintering process, we have controlled the degree of particle connectivity yielding a crossover in the behavior of acoustic excitations ranging from confined modes to propagating phonons. This transition has been correlated also to the surface morphology by AFM. Fully sintered films are characterized by extended "fibrillar" crystalline regions embedded in a disordered matrix, which still retain features of the original particulate structure. [ABSTRACT FROM AUTHOR]