Combinatorial Science - Coating Formulation
The preparation of coating formulations involves the dispensing and mixing of a variety of polymers, crosslinkers, catalysts, and other additives. Many resins and crosslinkers are relatively high viscosity materials and can be difficult to handle. Dispensing of these resins is accomplished through the use of disposable pipette tips and mixing by magnetic stirring. By using a disposable tip for each dispense, the chance for cross contamination is reduced and the need to thoroughly wash the pipette between each use is eliminated.
This coating formulation station is fitted with a custom designed viscosity measurement tool, which can measure the viscosities of the coating formulations (up to 1000 cps) as they are created. By setting a target viscosity for the entire library, the station will automatically measure the viscosity, dilute with solvent, mix, and measure again until all of the samples in the library have similar viscosities. This is important as the library is passed onto the next station where the polymers are coated onto substrates. Any changes in the compositions of the library are automatically updated in the database to maintain accurate information as the library progresses through the workflow.
Formulations can also be carried out on a bench top system from Symyx Tools. This unit features 24 mini blenders for the mechanical high shear mixing of viscous liquids. The aggressive mixing allows for the incorporation of powder components such as fillers and pigments. Liquid dispensing is performed using positive displacement disposable pipette tips and can be delivered on a volumetric or gravimetric basis. Liquid reagents are positioned in heated and magnetically stirred bays adjacent to the mini blenders. NDSU has developed a disposable cup that can be used in place of the blender module and is magnetically stirred. This cup can then be further mixed off-line on a dual axis centrifuge mixer capable of mixing paste-like materials. pH and conductivity probes are also incorporated into the unit.