DSC and TGA characterization of free and surface water of colloidal unimolecular polymer (CUP) particles for coatings applications

Colloidal unimolecular polymer (CUP) particles are spheroidal nano-scale and 3–9 nm that can be easily designed and controlled. The formation of CUP involves simple synthesis and water reduction. These nanoparticles have charged hydrophilic groups on the surface and are surrounded by a layer of surface water that does not freeze until very low temperature. CUPs have very high surface area per gram, which gives them a high nonfreezing water content. The CUP system is free of surfactant and has zero VOC, exhibiting great potential for coatings applications. The amount and thickness of the surface water were determined by differential scanning calorimetry (DSC) using the heat of fusion. The solution density and knowledge of the resin density and the composition of the CUP solution were used to determine the density of surface water. The evaporation rate of free water and surface water in CUP solutions were investigated by thermogravimetric analysis (TGA) and showed the effect of CUP on the evaporation rate. CUP as an additive to give freeze thaw stability, wet edge retention and open time improvements were explored. Excellent performance in freeze thaw, wet edge time improvement and more open time was found. The CUP system offers an excellent alternative to form zero VOC waterborne coatings.