Doctoral Defense: Philip Adamek

In his PhD, Philip established a melt milling process for the formulation of poorly water‑soluble drugs as a solid crystalline suspension (SCS). By executing a top-down wet milling approach in a molten carrier, the drug was selectively ground to the submicron (0.1‑1 µm) region.

Using a custom‑built annular gap batch mill, SCS containing >90 % submicron particles were achieved under optimized process conditions. The dissolution of the obtained product was greatly improved compared to other state-of-the-art processes in that domain. However, agglomeration was found to be the limiting factor for this performance metric.

With the introduction of the anionic surfactant sodium dodecyl sulfate as an additive, the redispersion of primary particles was achieved. At 1 wt.% the surfactant initiated a foaming process of the molten carrier, leading to the adsorption of individual particles at the gas‑melt interface. This underlying mechanism and its driving forces were revealed through various experiments and imaging techniques. Based on the working principle it was termed “melt foaming” and differs from particle stabilization mechanisms previously reported in literature.

Building on the batch results, this work also demonstrated the transfer of the melt milling process to the technical scale. A continuous process, transforming a powder mixture into a processed SCS in a single passage, was developed and successfully tested. The main equipment, a continuous annular gap mill, was built and operated, achieving 80-90 % submicron particles, making this a promising process for industrial application.

Philip is continuing his professional journey as Plant Assistant Manager at the surfactants plant of Evonik AG in Essen.