Low-friction silicone surfaces via mold texturing and uv-ozone treatment

Overview

This technology reduces the coefficient of friction (CoF) of silicone elastomers without changing the material composition or adding any low-molecular-weight species. Friction is set mechanically by imposing a defined surface morphology directly from the mold and then converting the outermost layer with a controlled UV-ozone (UVO) treatment. Because no oil, softener, coating, or additive is introduced, there are no mobile species that can migrate to the surface over time, preventing the drift in surface properties often seen in conventionally modified silicones.

The approach targets a CoF of 0.4–0.6 with surface stiffness in the 10–100 kPa range, using a commercially available low-extractables silicone as the base material. Applications include seals, gaskets, elastomeric grips, medical device surfaces, and other silicone components where long-term, stable low friction is required without bleed-out or contamination.

Technical specifications

How it works:

• Surface morphology is set directly from textured tooling, controlling real contact area and thus adhesion-dominated friction.
• Depth-controlled UV-ozone treatment converts the outermost silicone layer into a silica-like, stiffer surface, independently tuning tack, wettability, and contact modulus.
• Morphology and UVO depth are independent parameters, allowing simultaneous optimization of friction and surface mechanical response.

Key features:

• No added mobile species; surface properties are intrinsic to the treated material, so there is no driving force for drift.
• The low-extractables base silicone removes the main aging pathway (hydrophobic recovery driven by chain migration) seen in conventional UVO-treated PDMS.
• Both processes are already used at production scale: textured tooling adds no cycle time, and UV-ozone is a dry, solvent-free step controlled by a single dose parameter.
• Molds can be generated by replicating existing commercial textures or precisely 3D-printed to cover a pitch, height, and roughness design space.

Technology readiness level

The technology is in the research and validation stage. Planned work includes selecting a commercial low-extractables silicone with appropriate bulk shear modulus and elasticity ratio, generating designed mold textures, mapping UV-ozone dose to converted-layer depth and surface energy, measuring friction under continuous shear, and verifying performance under accelerated aging. The integrated surface design has not yet been demonstrated on a finished product, but it builds on established physics and mature manufacturing steps, so the path to practical implementation is clearly defined.