Soft silicone elastomers with no chemical cross-linking and unprecedented softness and stability

Pengpeng Hu, Qian Huang, Peter Jeppe Madsen, Anne Ladegaard Skov*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

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For silicone elastomers used as actuators, softness is key for enabling actuation at low voltages. Recently, an extremely soft (Young’s modulus < 50 kPa) silicone elastomer without cross-links has been reported by Goff et al. Besides its extreme softness, the elastomer was reported to almost completely recover (82%) from a 10-cycle elongation of more than 5000%. This observation challenges conventional elasticity theory of cross-linked elastomers because a network without covalent crosslinks should not be able to strain-recover to such extent. In this work, the elastomer is hypothesized to be formed from concatenated rings through heterodifunctional uni-molecular ring closure. It is found that the elastic properties of this uncross-linked elastomer can be described by the dynamics of concatenated rings, which act as pseudo-crosslinks and pseudo-entanglements. Isolated rings and dangling rings function as external solvents and internal solvents respectively, thereby contributing to the unprecedented softness. The ability to precisely control the ratio between concatenated and dangling rings is expected to lead to even softer dielectric elastomers paving the way forward for ultra-soft robotics without significant mechanical losses.
Original languageEnglish
Title of host publicationElectroactive Polymer Actuators and Devices (EAPAD) XXII
EditorsYoseph Bar-Cohen, Iain A. Anderson, Herbert R. Shea
Number of pages9
PublisherSPIE - International Society for Optical Engineering
Publication date2020
Article number1137517
ISBN (Electronic)9781510635272
Publication statusPublished - 2020
EventSPIE Smart Structures + Nondestructive Evaluation - Online
Duration: 27 Apr 20208 May 2020


ConferenceSPIE Smart Structures + Nondestructive Evaluation
SeriesProceedings of SPIE - The International Society for Optical Engineering


  • Silicone elastomer
  • Softness
  • No crosslinking
  • Concatenated ring

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