Control of Heterogeneous Nucleation via Rationally Designed Biocompatible Polymer Surfaces with Nanoscale Features

Abstract

Direct control of nucleation in a crystallization process is difficult to achieve but offers many potential benefits to the food, chemicals, and pharmaceutical industries. We demonstrate a rational approach for designing and fabricating biocompatible polymer films that can drastically enhance nucleation rates and enable polymorph selection of small-molecule compounds. The core design philosophy was to calculate angles between major crystal faces and determine suitable substrate geometry to use for enhancing heterogeneous nucleation. Aspirin and indomethacin were used as model compounds; poly(vinyl alcohol) (PVA) with no additional chemical modification was made into films and imprinted with nanoscale features. Nucleation induction time experiments showed that using PVA films significantly reduced the nucleation induction time at a fixed supersaturation due to favorable chemical interactions and could be further reduced when the angles of the nano-indentations on the substrate matched the angles between di...