Odourless Alcohols Unlock Tougher 3D Printed Materials

In the precision world of lithography-based additive manufacturing, engineers often favour 'step-growth polymerisation'. This chemical process creates polymer networks that are significantly more homogeneous and tougher than those formed by standard chain growth methods. However, the prevailing technique—known as thiol-ene chemistry—has a distinct downside: the thiols required are scarce, chemically unstable during storage, and possess a notoriously strong, unpleasant odour.

New research presents a sophisticated solution by replacing these problematic thiols with alcohols. This alternative process, the oxa-Michael addition, utilises a wide variety of odourless alcohols to achieve the same structural benefits without the stench. The key innovation is the use of 'photocaged' Lewis base catalysts. These are powerful chemical triggers wrapped in a molecular cage, keeping them dormant and stable until they are exposed to light.

Once illuminated, the catalyst is released to drive the reaction, allowing for precise control over the photochemistry. The study confirms that this formulation offers superior storage stability at various temperatures compared to thiol-based predecessors. Furthermore, the team successfully applied this system to 'hot lithography'—a technique using heated resins—demonstrating its ability to produce durable, high-quality parts using both linear and non-linear light absorption.