Fabrication and characterization of UV-curable thiol-functionalized siloxane elastomers with enhanced adhesion for flexible substrates

• The new elastomers exhibit storage moduli that are 6 times and 37 times higher than those of PDMS at 25°C and 100°C, respectively, indicating enhanced mechanical stability. • The tensile strength of the elastomers is increased to 7.91 ± 0.62 MPa at a strain of 93.36 ± 4.11%, improving durability without significantly compromising flexibility. • Thermal conductivity of the elastomers is improved by 60%, and the coefficient of thermal expansion (CTE) is reduced by 26%, enhancing heat dissipation and dimensional stability under thermal stress. • The adhesion properties showed significant improvement, with peel-test adhesion strength reaching 7 times that of conventional PDMS. • LED thermal imaging data confirm the superior thermal management performance of the new elastomers, as LED arrays mounted on these substrates exhibit lower temperatures compared to those on PDMS substrates under the same conditions. The rapid advancement of flexible and wearable devices has increased the demand for substrate materials with excellent elasticity, biocompatibility, and transparency. Polydimethylsiloxane (PDMS) is widely used in these applications due to its advantageous properties. However, its inherently low surface energy limits its adhesion in high-stretchability contexts. To address this issue, various surface modification techniques have been developed, but these methods often alter the intrinsic properties of PDMS or introduce complexities in the manufacturing process. This study proposes elastomers based on ultraviolet (UV)-curable siloxane resins, which retain outstanding flexibility and transparency while significantly enhancing adhesion properties. UV-curable siloxanes were synthesized to prepare elastomers that were evaluated for their mechanical, thermal, and surface properties in comparison with PDMS. Results indicate that the prepared elastomers can be rapidly cured under UV exposure, achieving storage moduli 6 and 37 times higher than those of PDMS at 25°C and 100°C, respectively. Furthermore, thermal conductivity improved by 60%, and the coefficient of thermal expansion was reduced by 26%, demonstrating superior mechanical stability across diverse conditions. Adhesion properties were also markedly enhanced, as shown by peel-test adhesion strength that was 7 times greater than that of conventional PDMS.