Development of customized ultra-soft, oil-free silicone rubber formulations
Research program to develop customized, ultra-soft, oil-free silicone rubber formulations based on commercially available PDMS components. The approach reduces low-volatile constituents through vacuum and thermal pre-treatment, and optimizes curing and post-curing to create stable, loosely crosslinked elastomers. Target applications include soft sensors, soft actuators, and multilayer PDMS systems. Validation covers mechanical properties, processability, surface characteristics, and extractables, with aging and migration testing to confirm long-term stability.
Overview
This program develops customized, ultra-soft, oil-free silicone rubber formulations based on commercially available polydimethylsiloxane (PDMS) components. The work addresses a critical problem in soft robotics and flexible electronics: silicone oil migration from conventional soft PDMS networks, which can degrade material properties and sensor performance over time.
The resulting materials are intended for soft sensors, soft actuators, multilayer PDMS systems, and other applications requiring elastomers with low volatile content and stable long-term behavior. Because the approach builds on commercially available starting materials, it offers a practical path to production without relying on specialty or custom-synthesized polymers.
Technical specifications
The development approach combines material selection, pre-treatment, and formulation optimization:
- Screening of candidate PDMS polymers, crosslinkers, chain extenders, and monofunctional modifiers
- Vacuum and thermal pre-treatment to reduce low-volatile components in the base materials
- Systematic variation of molecular weight, functionality, functional-group stoichiometry, and modifier content to control viscosity and crosslinking density
- Optimized curing and post-curing conditions to produce a fully crosslinked, loosely networked elastomer
- Chemical analytical verification of the reduction or absence of low-volatility and non-covalently bound constituents
Selected formulations are validated for Young's modulus, elongation at break, processability, surface properties, and extractables. Soxhlet extraction and complementary analytical methods quantify unbound components, while aging and migration tests confirm long-term material stability.
Technology readiness level
The research group has demonstrated experience in developing soft silicone rubber formulations for sensor and actuator applications, including identification of silicone oil migration as a key failure mode in multilayer PDMS systems. The current program is at an early development stage: candidate materials and formulation parameters are being screened and validated, with full mechanical and chemical characterization planned. The technology is positioned for sponsored research collaboration to advance toward application-ready materials.
About Fraunhofer Institute
Fraunhofer is a large, multi-site applied research organization based in Germany, operating a nationwide network of institutes and research units with a strong industry-facing mission. Its contract-research model aligns work to real manufacturing and deployment needs, with pilot lines, test labs, and demonstration facilities for validation and scale-up. Many institutes are integrated with nearby universities and regional industry clusters, enabling joint appointments, shared infrastructure, and fast talent pipelines. Research is supported by competitive European programs alongside German federal and state funding, complemented by extensive contract revenue from private-sector collaborations. A dedicated technology transfer function manages IP, licensing, and startup formation.
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