The Replication and Stamping of Freely-Lying Particles

My summer internship was on The Replication of Freely-Lying Particles. Here I focused on the development of polymer materials for drug delivery applications using soft-lithography instruments. The goal was to find the surface energy where the liftoff of the micelles occurred from a piece of modified Silicon wafer onto the mold which is Perfluropolyether (PFPE). Then I needed to transfer the micelles from the mold to a fresh piece of unmodified Silicon wafer. The Silicon wafer was modified with a solution of 1:5 by weight of otyltrichlorosilane (OTS): Paraffin Oil. After the first Silicon wafer is modified and the micelles are spincasted to the modified Silicon wafer, then two scenarios can occur. The two scenarios can be that 1. The micelles can stick to the mold or 2. The micelles can stick to the substrate (Silicon wafer). Obtaining the surface energy requires a calculation involving the contact angle. The target contact angle was 40o-50 o. This equates to a target surface energy of 50-60 mJ/m2 for the liftoff of the micelle to the mold. Next the micelles on the mold had to be transferred from the mold to a fresh piece of unmodified Silicon wafer. This is called the Stamping process. The Stamping Efficiency was found to be between 20-25% of micelle transfer to the fresh, unmodified Silicon Wafer.