(8m) Study of the physical properties of UV-crosslinked poly(vinylmethylsiloxane)

Microfluidic devices allow the integration of different unit operations into a single piece of equipment resulting in a more efficient and economical manufacturing process. Siloxane elastomers, widely used soft materials, are at the basis of high performance rubbers combining extremely low glass transition temperature, outstanding thermal stability, resistance to oxidation and to energetic beams, good dielectric properties, biocompatibility and high hydrophobicity. Poly(dimethylsiloxane) (PDMS) is a widely used material for microfluidic device fabrication. However, it has many drawbacks: it contaminates microfluidic solutions with unreacted oligomers, absorb organic molecules from solution, and swell upon exposure to most organic solvents. Another drawback of PDMS is that it contains methyl side groups which are difficult to modify chemically. These limitations can be overcome by utilizing poly (vinylmethylsiloxane) (PVMS) as an alternative to PDMS. PVMS contains vinyl groups in its structure providing the ability to modify it chemically or mechanically. Cross-linked PVMS forms elastomeric networks that behave similarly to PDMS networks, exhibiting low surface energy, low modulus, mechanical flexibility, optical transparency, and hydrophobicity. Investigation of the physical properties of ultraviolet (UV) light crosslinked PVMS materials can open a new dimension in the arena of mechanically tunable PVMS films which can be utilized as an effective material for microfluidic device fabrication. In our study, we observed the effect of degree of crosslinking on the physical properties of PVMS utilizing a free radical photo-initiator to prepare crosslinked PVMS films at room temperature. Additionally, mechanical properties of the crosslinked films were studied using a Tribometer. Furthermore, Fourier Transform Infrared Spectroscopy studies showed that crosslinked PVMS contains unconverted vinyl groups in its structure providing the capability for further modification.