CHARACTERIZATION OF PDMS INTERACTION WITH HALOGENATED AND NON-HALOGENATED SOLVENTS VIA SWELLING AND THERMAL ANALYSIS

Abstract

Polydimethylsiloxane (PDMS) is a silicone-based elastomer that is commonly utilized in biomedical, membrane, and flexible material applications due to its temperature stability, chemical resistance, and flexibility. However, its sensitivity to swelling in different solvents can have a considerable impact on its mechanical performance and long-term stability. To better understand the polymer-solvent interaction and heat response, this work investigates the swelling and deswelling behavior of PDMS in selected halogenated and non-halogenated solvents, specifically 1-bromohexane, 1-bromooctane, 1-bromodecane, 1-bromotetradecane, 1- chlorodecane, and n-hexane. Gravimetric swelling measures were performed, and deswelling was tracked over time in 1-bromotetradecane. Hansen Solubility Parameter (HSP) study predicted compatibility results revealed that short-chain and volatile solvents caused higher swelling, while long-chain solvents exhibited limited diffusion but stronger retention, while FTIR spectroscopy revealed solvent-specific interactions. Thermogravimetric analysis (TGA) evaluated thermal desorption behavior and stability, while differential scanning calorimetry (DSC) analyzed heat flow alterations and plasticization effects. The findings revealed that smaller molecular weight solvents, such as n-hexane and 1-bromohexane, caused more swelling and faster evaporation, whereas longer-chain solvents, such as 1-bromotetradecane, caused slower desorption due to deeper diffusion and greater affinity. Despite substantial solvent uptake, PDMS maintained thermal stability under all test conditions. The findings highlight how solvent polarity, molecular size, and volatility affect PDMS behavior, providing useful information for solvent selection in applications where PDMS is exposed to organic liquids.