Driven by the continuing discussion on safety and quality of silicone breast implants, they have turned into focus of this study with respect to the increased amount of potentially toxic low molar mass components in the PIP silicone breast implant gels [1, 2, 3]. The diffusion coefficient of silicone oils into silicone elastomers were analysed by means of the crosslink density and the penetrant size. The study was focused on the diffusion of cyclic siloxanes, Octamethylcyclotetrasiloxane (D4), Decamethylcyclopentasiloxane (D5) and Dodecamethyl-cyclohexasiloxane (D6) besides of linear siloxanes due to their potential occurrence in silicone breast implants [2]. The analysis of the diffusion behavior was carried out with tailor-made silicone elastomer samples varying in crosslink density. Therefore, sorption experiments according to past studies of Gedde and his team were performed. The subsequent evaluation of the sorption data yields to the corresponding diffusion properties [4]. Based on the diffusion coefficient related to the crosslink density a model was developed to describe the material behavior. In addition, the mechanical properties were analysed of samples with various degrees of swelling. REFERENCES 1. D. W. Schubert et al., Polym. Int. 63, 172–178 (2014). 2. Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR), “Preliminary Opinion on the safety of Poly Implant Prothèse (PIP) Silicone Breast Implants,” (European Commission, 2013 update). 3. K. M. Pieńkowska, “Chapter 16: Safety and Toxicity Aspects of Polysiloxanes (Silicones) Application”, Concise Encyclopedia of High Performance Silicones, edited by A. Tiwari and M. D. Soucek, John Wiley & Sons, Inc., Hoboken, NJ, USA, pp. 243–251 (2014). 4. U. W. Gedde et al., Polym. Eng. Sci. 36 (16), 2077–2082 (1996).