Characterization of polymer thin films by phase-sensitive acoustic microscopy and atomic force microscopy: a comparative review

The potential of phase-sensitive acoustic microscopy (PSAM) for characterizing polymer thin films is reviewed in comparison to atomic force microscopy (AFM). This comparison is based on results from three-dimensional vector contrast imaging and multimodal imaging using PSAM and AFM, respectively. The similarities and differences between the information that can be derived from the AFM topography and phase images, and the PSAM phase and amplitude micrographs are examined. In particular, the significance of the PSAM phase information for qualitative and quantitative characterization of the polymer films is examined for systems that generate surface waves, and those that do not. The relative merits, limitations and outlook of both techniques, individually, and as a complementary pair, are discussed.     

Advances in phase‐sensitive acoustic microscopy studies of polymer blend films: annealing effects and micro‐elastic characterization of PS/PMMA blends

The unique phase‐sensitive acoustic microscope is used for the structural and mechanical characterization of thin films of polystyrene/polymethylmethacrylate blends. The effect of annealing on blends of polystyrene/polymethylmethacrylate spin coated from different solvents unto a substrate is studied. Varying the solvents according to vapour pressure and spin coating at different speeds (for thickness variation) led to changes in phase domain distributions and overall structural properties before annealing. Annealing in vacuum at 190°C for 48 h resulted in the elimination of solvent effects with all samples reverting to a similar morphology irrespective of common solvent and thickness. The Young's moduli at specific points on the film (E_polystyrene= 3.4 ± 0.3 GPa, E_{polymethylmethacrylate}= 4.2 ± 0.4 GPa) and over a given area (E_{polystyrene/polymethylmethacrylate}= 3.9 ± 0.4 GPa) were determined by combinatory use of the atomic force microscope and phase‐sensitive acoustic microscope. These results demonstrate a minimally invasive method for the quantitative characterization of polymer blend films.