Rheological Investigation of Polydimethylsiloxane with Glass Beads: A Model for Compression-Stiffening Effects in Soft Tissue Engineering

This study explores the rheological properties of polydimethylsiloxane (PDMS) composites with glass beads (GBs) to replicate the compression-stiffening behavior of biological tissues. The mechanical properties of soft tissues arise from interactions between the extracellular matrix (ECM) and embedded cells. To mimic this, PDMS was used as a polymeric matrix, while rigid GBs acted as non-deformable inclusions facilitating stress redistribution. PDMS composites with 10%, 20%, and 30% GB concentrations were fabricated. Rheological analysis revealed that GBs significantly enhanced the storage modulus (G'), with stiffness increasing linearly under compression. The stiffening rate rose from 300 Pa/% (pure PDMS) to 387 Pa/%, 836 Pa/%, and 2035 Pa/% for 10%, 20%, and 30% GB, respectively, marking a sevenfold increase at the highest concentration. Similarly, the apparent Young's modulus increased from 150 kPa (pure PDMS) to 200 kPa, 300 kPa, and 380 kPa for composites with 10%, 20%, and 30% GB, respectively. PDMS-GB composites successfully reproduce the compression-stiffening effect observed in biological tissues, which may aid research in mechanobiology and tissue engineering.