Polydimethylsiloxane (PDMS) has been widely used in a variety of biomedical applications: microfluidic device, implant, and biomedical phantom due to its unique physiochemical and mechanical properties. To use PDMS properly, in-depth study for properties of PDMS is needed. Many studies for analysis of PDMS properties are suggested, however, there are shortages of systematic analysis and study on the origin of PDMS properties.
Typically, PDMS is produced by mixing and curing pre-polymer and curing agent with catalyst and thermal energy. The recommended mixing ratio (pre-polymer: curing agent) is typically 10:1 by raw materials suppliers. However, the reason why the mixing ratio 10:1 is considered proper than other mixing ratios has not been known clearly.
In this research, we presented the change of physicochemical properties of PDMS according to the mixing ratio and figured out the origin to change PDMS physiochemical properties by Raman spectroscopy and absorption spectroscopy.
We produced PDMS samples with various mixing ratios(1:1, 1.5:1, 2:1, 3:1, 5:1, 7:1, 9:1, 10:1, 12:1, 20:1, 30:1) and analyzed mechanical, optical, and surface properties of PDMS by measuring Young’s modulus, OCT, hydrophobicity, and surface profiles according to the mixing ratio of PDMS. Also, we demonstrated the chemical composition of PDMS is changed when the mixing ratio of PDMS is changed by measuring Raman spectra and absorption spectra.
As a result, when the mixing ratio is about 9:1, the mechanical, optical, and surface properties of PDMS had extreme points and the reason was explained quantitatively with the data of Raman spectra and absorption spectra.