With combinatorial materials research (CMR), a new research approach toward the development and optimization of materials has been established at BASF. While adopting the basic ideas of combinatorial chemistry, CMR faces a whole bunch of challenges throughout the entire combinatorial process loop. New concepts for sample preparation on a smaller scale, i.e. synthesis and formulation, for parallel or fast sequential screening and characterization, and for appropriate management of yet unknown amounts of data have been developed. The integration of as many as possible workflow steps and the interplay of experts from various relevant fields, such as chemistry, engineering, robotics, informatics, and physics, are necessary. First results in the fields of polymer synthesis and coatings formulation give an impression of the innovative power and efficiency of this new kind of research. magnified image

The adsorption of thermally sensitive poly(N-isopropylacrylamide) (PNIPAM) on surfactant-free polystyrene latex was used as a model system to study the effect of chain hydrophobicity on the adsorption of protein on hydrophobic surface. PNIPAM is only soluble in water at lower temperatures with a lower critical solution temperature (LCST) of ∼32 °C. Using PNIPAM, we were able to continuously adjust the chain hydrophobicity and manipulate the adsorption by a simply temperature variation. A combination of static and dynamic laser light scattering was used to study the amount of the adsorption and the thickness of the adsorbed polymer layer. We found that there existed a hysteresis of the adsorption in the heating-and-cooling cycle, indicating an additional adsorption at temperatures higher than the LCST. We also found that the heating rate could greatly affect the adsorption. Our results revealed that the desorption accompanying the swelling of the adsorbed PNIPAM layer was logarithmically proportional to the desorption time, indicating a diffusion-controlled process.

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