Processing and adjusting the hydrophilicity of poly(oxymethylene) (co)polymers: nanoparticle preparation and film formation

Handling the insoluble POM: the preparation of nanoparticles based on hyperbranched-linear-hyperbranched ABA triblock copolymers with variable hydrophilicity and composed of short hyperbranched polyglycerol (hbPG) as the A-blocks and linear poly(oxymethylene) (POM) as a B-block is described. The POM-hbPG-nanoparticles with diameters in the range of 190 to 250 nm were generated in a convenient process, combining the solvent evaporation process with the miniemulsion technique, a water borne handling for POM-copolymers. Furthermore, the film formation properties of the nanoparticles were investigated by deposition on silicon and subsequent sintering, which leads to films with a thickness in the μm-range that were investigated via SEM. The surface properties of these films were investigated via static contact angle measurements at the liquid/vapor interface. The contact angle decreases from 67° for the polymer film based on POM with two hydroxyl end groups to 29° for POM-copolymers with 16 hydroxyl groups, confirming the influence of the polymer structure and size of the hbPG block on the surface properties. In summary, this work presents a possibility for a facile handling and film formation of the insoluble POM, opening new applications, e.g., in coatings.