Terahertz optical response of silicone-based polymers: Chain-length effects and backbone-dependent molecular interactions

Abstract

Using THz time-domain spectroscopy, we investigated PDMS samples with different polymer chain lengths and found that variations in molecular weight produce distinct refractive index and absorption patterns, even though the backbone structure is identical. We further compared PDMS with polymethyl-hydrosiloxane (PMHS), which contains Si-H units in the main chain, and observed significantly stronger THz absorption in PMHS. Differences between hydroxyl-terminated and methyl-terminated PDMS also showed measurable spectral changes. These results demonstrate that THz waves are highly sensitive to subtle chemical variations in silicone-based polymers, suggesting promising applications in polymer quality inspection, material diagnostics, and THz photonic device development. © COPYRIGHT SPIE.