Mesoscale Acoustics on Soft Matter systems
Final Report Abstract
“Mesoscale acoustics on soft matter systems” is an in-depth look at the potential of the vectorcontrast phase-sensitive scanning acoustic microscope (PSAM) in studying soft matter systems on a mesoscopic scale. Work was done on both synthetic and biological polymer systems. Polymer blends of polystyrene and poly(methylmethacrylate) were used as typical synthetic samples, while chitosan films were used as samples of biomaterials. The choice of the PS/PMMA blend was in accordance to the technological interest in such films. Also the blend has been studied a lot in the past decade and as such, provided a good basis for comparison. Chitosan, a derivative from chitin that is prominent in the carapaces of crustaceans has been of interest lately in medical applications and food processing. So a non-destructive study of the microstructure, morphology, and micro-elastic or -mechanical properties was deemed necessary. A number of methods available in our laboratory or at the partners in Orlando were used. These included phase-sensitive acoustic microscopy (PSAM), confocal laser scanning microscopy (CLSM), atomic force microscopy (AFM). A combination of some of these techniques with the PSAM proved to be an even better solution to problems involving both qualitative and quantitative characterization. The polymer blend films were the most interesting sample systems in this work (from an experimentalist point-of-view), since they could be designed and modified easily. The effect of solvent vapor pressure on morphology was successfully investigated for thin film blends of PS and PMMA with interesting results. The changes in phase separation on the film surface and the morphology in general with respect to temperature, solvent, spin-coating speed and other tailoring parameters were investigated. Optimizing the derivable information from the phase-contrast image of the PSAM, e.g. by development of optimum models for processing phase information in polymer thin films was one of the goals and this was achieved by a model for the determination of the speed of sound in the blend films by making use of the PSAM phase information proved successful, yielding values which agree quite well with the literature. A combination of the AFM and PSAM was used to evaluate the acoustic and elastic properties of thin polymer blend films on substrate. Another such model “the polar plot model” was used to evaluate a film of chitosan. The access to relevant information from speed of sound to attenuation and elastic modulus is indicative of the importance of the PSAM in soft matter studies. The very notion of material characterization is epitomized in this example, where the film of chitosan is imaged and using PSAM only, the mechanical properties are derived. This project was a big step in the right direction for non-invase (non-destructive) detailed evaluation and characterization of soft matter systems. These models could be further used in the investigation of other thin soft films in technological application or in the characterization of biological specimen such gelatin, collagen, cellulose, and cells. These are a good starting point for research in nondestrutive characterization of thin soft samples. The case of biological cells is particularly interesting, since a lot of questions concerning mechanical and elastic properties remain unanswered in cell biology.
Publications
- “Combinatory scanning confocal laser and acoustic vector contrast microscopy: multi-contrast imaging of soft matter samples”, Proc. SPIE 6177, 617712 (2006)
A. Kamanyi, R. Wannemacher, W. Grill
- “Combinatory acoustic and confocal laser microscopy as a tool for material characterisation of thin films: Morphology studies in thin films of polymer blends”, Proceedings of the 4th International Conference of MRS-Africa, Dar es Salam, Tanzania (2007)
A. Kamanyi and W. Grill
- “Soft matter Acoustics: Non-destructive health monitoring of polymer blend films”, Proc. SPIE 6531, 653106 (2007)
A. Kamanyi, W. Ngwa, T. Kundu, W. Grill
- “Determination of mechanical properties with vector-contrast acoustic microscopy by polar diagram image representation”, Proc. SPIE 6935, 69351Z (2008)
E. T. Mohammed, A. Kamanyi, K. Hillmann, R. Wannemacher, W. Grill
- “Effects of solvent vapor pressure and spincoating speed on morphology of thin polymer blend films”, Proc. SPIE 6935, 69351X.1 (2008)
A. Kamanyi, W. Ngwa, W. Luo, W. Grill
- Advances in Phase Sensitive Acoustic Microscopy Studies of Polymer Blend Films: Annealing Effects and Micro-elastic Characterization of PS/PMMA Blends”, J. Microsc. 238, 134–144 (2010)
A. Kamanyi, W. Ngwa, W. Luo and W. Grill
- Mesoscale characterization of soft matter systems by phase-sensitve acoustic microscopy, Dissertation, Universität Leipzig (2010)
A. Kamanyi
- “Ultra-high resolution thin film thickness delineation using reflection phase-sensitive acoustic microscopy”, in Acoustical Imaging 30, (J. Jones, H. Lee, Eds.), Springer, Amsterdam (2010)
E.T. Mohammed, A. Kamanyi, K. Hillmann, R. Wannemacher, W. Grill
